Misstatements About Lonni Sue Johnson Are Like Misstatements About Henry Molaison

 A recent article in Scientific American is an article entitled "You Don't Remember Being a Baby, But Your Brain Was Making Memories."  The article provides no real evidence that brains create memories, and  its attempts to support such a claim are mostly references to junk science studies. 

The author is a neuroscientist named Nick Turk-Browne who fills up his article with unfounded claims and bad reasoning. First he suggests the reason people cannot remember their first five years is that the hippocampus is not active during those years. That makes no sense. The hippocampus is active during the first five years of life. 

Turk-Browne then repeats the very frequently repeated false claim that patient H.M. (Henry Molaison) suffered hippocampus damage in adulthood that made him unable to form new memories, saying that Henry Molaison was "unable to store memories,"  The claim is not true. 

Henry Molaison (patient H.M.)  was able to remember very many things from his life before his hippocampus damage. A 14-year follow-up study of patient H.M. (whose memory problems started in 1953) actually tells us that H.M. was able to form some new memories. The study says this on page 217:

"In February 1968, when shown the head on a Kennedy half-dollar, he said, correctly, that the person portrayed on the coin was President Kennedy. When asked him whether President Kennedy was dead or alive, and he answered, without hesitation, that Kennedy had been assassinated...In a similar way, he recalled various other public events, such as the death of Pope John (soon after the event), and recognized the name of one of the astronauts, but his performance in these respects was quite variable."

Another paper ("Evidence for Semantic Learning in Profound Amnesia: An Investigation With Patient H.M.") tells us this about patient H.M., clearly providing evidence that patient HM could form many new memories:

"We used cued recall and forced-choice recognition tasks to investigate whether the patient H.M. had acquired knowledge of people who became famous after the onset of his amnesia. Results revealed that, with first names provided as cues, he was able to recall the corresponding famous last name for 12 of 35 postoperatively famous personalities. This number nearly doubled when semantic cues were added, suggesting that his knowledge of the names was not limited to perceptual information, but was incorporated in a semantic network capable of supporting explicit recall. In forced-choice recognition, H.M. discriminated 87% of postmorbid famous names from foils. Critically, he was able to provide uniquely identifying semantic facts for one-third of these recognized names, describing John Glenn, for example, as 'the first rocketeer' and Lee Harvey Oswald as a man who 'assassinated the president.' Although H.M.’s semantic learning was clearly impaired, the results provide robust, unambiguous evidence that some new semantic learning can be supported by structures beyond the hippocampus proper."

Turk-Browne also makes the claim that because of a bad case of a  hippocampus damage, Lonni Sue Johnson was "unable to store memories."  That claim is also untrue.  Lonni Sue Johnson had very bad brain damage after a case of viral encephalitis. She was discussed at length in a book "The Eternal Now" by Michael D. Lemonick. But on page 13 of the preface of the book, we read a different claim. Instead of someone claiming that Lonni Sue Johnson could not form any new memories, we merely read that "she could no longer form new memories that she'd be able to rely on in the future, except in the most rudimentary way." This is an admission that Loni Sue Johnson could form new memories. 

We can have some skepticism about such a claim, because it is by an author trying to present a compilation of interesting cases of loss of memory, and such a person may be motivated to exaggerate memory loss, to make the story more interesting and the book more marketable. 

Lemonick's makes generalizations that the memory of Lonni Sue Johnson that we should take with some skepticism, because they are not established by formal tests. What seems to often be happening is that Lemonick is making generalizations based on limited anecdotal evidence, generalizations that may be hasty generalizations that would be disproven by extended formal testing.  

Lemonick tells us that Lonnie Sue Johnson had a big hole in the center of her head. That may have affected her recognition memory and her visual acuity.  So when we later read about Lonnie failing to recognize someone she had previously met, that is no proof of an inability to form new memories. It may be mere evidence of a visual problem or a recognition problem. 

So, for example, when Lemonick tells us on page 9 that "if she sees someone new, then sees them again a day later (or even five minutes later, as I discovered for myself), she'll have no idea that she ever saw them before," we do not actually know that this is some inability to form new memories.  It could be some mere difficulty in visual recognition or visual perception. Or, it could be that Lemonick is wrongly making sweeping generalizations based on very little data. If someone does not recognize you after meeting you a few minutes before, that is nowhere close to sufficient evidence that the person is unable to form new memories. 

The claim that Lemonick makes on page 9 that Lonni had lost memory of some of her family members is another claim that we should treat with suspicion. It may be a claim based mainly on a failure of visual recognition. Lemonick makes statements such as "she didn't know Kay, or her daughter Maya," referring to someone who was not Lonni's daughter. But what justification does Lemonick have for such claims?  How does he presume to know what a brain-damaged person did or did not know or remember when seeing some friend or her daughter?  Was the claim based merely on a failure of Lonni to recite their names after seeing them? We don't know. 

What we need here is some systematic procedure to test such a claim that a memory of someone's daughter had been lost. Such a procedure would include both a test of visual recognition, and a transcript of a long interview.  The interview might ask questions such as "Do you remember Kay?" and "Have you ever heard the voice that will speak next?" and "Do you recognize the face you will see next?" and so forth.  But we don't get details of any such a procedure.  We mainly get Lemonick kind of presuming what Lonni did or did not remember, based on thin evidence. 

On the next page (page 10) it becomes clear that the heavily brain-damaged Lonni did not lose all her memories of the past. We read that "she knows Maggi and Aline, but when you show her photographs of her aunts and uncles, she recognizes only some of them." We read that "she does know that she once had two airplanes." When Lemonick claims that Lonni does not remember her wedding day or her divorce, we should treat such claims with great skepticism, because they are not backed up by any quotes that Lemonick gives. And if you have a  quote from someone saying she does not remember some event, that does not well prove that the person has no memory of such an event. Ask the right questions at different times, and the same person may give you some details of the event. For example, ask a person about Napoleon, and she may say, "I don't remember anything about Napoleon." But then ask about Napoleon's final battle, and you may get an answer of "Waterloo." I can hardly overemphasize the importance of this point. Single-statement self-reports by a person about what he remembers on a topic may be very unreliable. And such self-reports coming from brain-damaged persons may be particularly unreliable. 

Often when a person says that he does not remember anything about some topic, it's just a way of indicating that the person does not want to be bothered with trying to recall what he remembers about that topic. Ask an adult what he remembers about the war of 1812, and there's a good chance he may say something like, "I don't remember anything about that." But ask the same person whether he remembers any fire occurring during that war, and there's a good chance the person may give an answer such as, "Yes, I remember the British burnt the White House," referring to an event of that war.  It is easy to imagine possible reasons why someone who got divorced might make some statement sounding like she does not remember her wedding or her divorce (for example, the person might be making an excuse to avoid recalling possibly painful memories of an unsuccessful marriage). 

Later on the same page when Lemonick claims that Lonni had lost "just about every other memory she'd accumulated in fifty-seven years of life," we should doubt very much that Lemonick is speaking correctly. What is the justification for such a claim? Was some formal standard test done to justify such a claim? Or is Lemonick simply making guesses about what Lonni remembers?

I made a search on Google Scholar for scientific papers referring to Lonni Sue Johnson. I was unable to find a single scientific paper that mentioned her using that name. I did find an article by a science writer, one claiming that Lonni "could not form new memories." That does not match the previously quoted statement by Lemonick suggesting that Lonni could form "rudimentary" new memories. The article presents no data supporting this claim that Lonni Sue Johnson could not form new memories. The article refers to "published studies of her memory after the viral attack."  We have some citations at the end of the paper. Only one of the papers cited refers to Lonni Sue Johnson, using the initials L. S. J.  The paper is behind a paywall, but the abstract of the paper does not mention any inability of this L. S. J. to form new memories. 

The claim in the article above does not match what we are told in a 2016 Johns Hopkins article, which merely says that Lonni Sue Johnson had a "severely restricted ability to learn new facts," which is different from being unable to learn new facts. 

The video here shows a picture of Lonni Sue's brain, showing severe damage, with the black areas being places hollowed out by the virus:

We hear a narrator (whose claims should be taken with skepticism) claiming that Lonni Sue lost almost all of her memories. But around the 2:50 mark we hear Lonni Sue successfully and very rapidly reciting all of the letters in the alphabet in correct order, performance seemingly incompatible with the narrator's claim. Around the 3:00 mark the narrator says Lonni Sue has "a little ability to create new memories," contrary to Turk-Browne's claim that she could not form new memories.  At the 3:28 mark we see Lonni Sue playing what looks like a violin very well (the instrument seems to be a viola). Around the 5:36 mark we see very good drawings Lonni Sue made after her brain damage. 

Around the 5:56 mark we hear Lonni Sue speaking like a normal person, saying art "is a language, a visual language, that you can reach everyone of every nationality," and that "writing is fun too." Around the 8:30 mark we hear Lonni Sue sing-speaking, singing in an apparently improvised melody. 

Another video on Lonni Sue has the phony title "The Woman Who Lost All Her Memories," a title not matching the facts of the case described above. The video provides no evidence to support the claim that Lonni Sue could not form new memories. 

In this case we are lacking any systematic evidence for the claim that Lonni Sue Johnson could not form new memories. For such a claim to be made with credibility, we would need something like a transcript of a long interview, or the results of hours of systematic testing. A failure of someone to recognize a person they had met before is not good evidence of an inability to form new memories.  Such a failure could be due to visual processing defects and visual recognition problems that are mainly related to vision rather than memory. 

Remembering that old slogan "extraordinary claims require extraordinary evidence," we can translate the slogan to mean "you should have very strong evidence before making a claim of the extraordinary."  The claim that Hubert Pearce had extrasensory perception is an extraordinary claim, but it is backed up very well by many hundreds of hours of very careful tests that Professor Joseph Rhine did with Hubert Pearce (tests described here).  The claim that Alexis Didier had powers of clairvoyance is an extraordinary claim, but it is supported by endless successful tests performed of Alexis Didier, some of which are described here. No one should be making a claim that Lonni Sue Johnson could not form new memories unless they have very strong evidence to back up such a claim, such as a long, detailed scientific paper giving the results of very careful tests of her. Such evidence seems nowhere to be found. 

Lack of motivation by someone asked a question is usually a more plausible explanation for a lack of an answer than some explanation of an inability to learn. Claims of an inability to learn would be far more convincing if they were backed up by careful tests repeated many times, in which subjects were strongly motivated to perform highly.  You can imagine all kinds of ways to motivate better performance, such as offering 300 dollars for each item recalled.

He may be wrongly reported as having antegrade amnesia

In my next post in a few days I will discuss other misstatements in the Scientific American article, in which we hear a discussion of   neuroscience experiments done on infants, experiments I will criticize as being goofy and reckless.  We should always remember that when it comes to cases of memory difficulties, the world of neuroscience literature is a "give them an inch, and they'll take a mile" affair. We should remember that there is a very strong incentive for people to make cases of memory difficulties sound worse than they are, because such claims may increase citation counts and book sales and video viewership, in a way that leads to greater profit or success for someone engaging in such exaggerations, and because such claims may be made by those very eager to conjure up claims that may seem to support "brains store memories" dogmas. 

Postscript: One of the earliest papers on Lonnie Sue Juhnson is the paper "The necessity of the mediat temporal lobe for statistical learning,"  which you can read here. In that paper we read about Lonnie Sue Johnson, with the paper using only her initials. The paper claims, "In the autobiographical domain, extensive testing has revealed no memory for specific life events; for example, LSJ is unable to report anything about her 10-year marriage." This statement must be treated with very great skepticism, for a variety of reasons. First, the authors fail to describe in any detailed way any such testing. Secondly, the claim conflicts with statements above, in which Lonnie Sue Johnson does display memories of specific life events.  The most reasonable explanation here is that the authors asked a few questions (or an insufficient number of questions) about autobiographical events and failed to get answers, with the authors unjustifiably jumping to the unjustified conclusion or insinuation that Lonnie Sue Johnson had no memory of autobiographical events.  

I cannot emphasize too strongly the point that someone's failure to answer a small number of questions about autobiographical events is no good evidence for a lack of autobiographical memory. There are 101 reasons why a subject might not answer questions about his life history when asked such questions, reasons other than an absence of autobiographical memory. To have even mere prima facie evidence for a lack of autobiographical memory, some scientific paper author would have to document an exact series of questions and answers asked at different intervals stretching over many different days. Such questions would have to have a variety of different forms, being more than just free recall questions. So, for example, if a subject with a husband named David were to be tested for autobiographical memory, the subject might at some time be asked "tell me about your husband," and at other times asked "tell me about David," and at other times asked "tell me about your marriage," and at other times shown a picture of David, with the question, "Do you recognize this man?" Such questions would have to be repeated on various different days, with the exact questions and answers being documented. Nothing of the sort is documented in this scientific paper "The necessity of the mediat temporal lobe for statistical learning." So we should be very skeptical about its claim that "extensive testing has revealed no memory for specific life events;"  The authors fail to substantiate this claim. The authors tell us this about Lonnie Sue Johnson:

"LSJ scored in the normal range on tests of single-word reading and spelling (Wide Range Achievement Test III, Wilkinson, 1993: 58th and 55th percentile, respectively) and vocabulary (PPVT-R, Dunn & Dunn, 1981: 63rd percentile). Anecdotally, her language comprehension and production seem normal. LSJ’s visuospatial abilities also appear intact: Her performance was normal on the Block Design and Matrix Reasoning subtests of the WAIS-IV (Wechsler, 2008) and on all subtests of the Visual Object and Space Perception Battery (Warrington & James, 1991)."

Seeming to speak in a very inappropriate manner, the authors causally claim that Lonnie Sue Johnson has an "inability to form new memories"; but they fail to discuss any tests demonstrating this claim.  As evidence for this claim, they merely offer weak anecdotal evidence, saying, "Anecdotally, LSJ consistently shows no recollection for tasks when questioned after completing them and expresses no recollection for experimenters across sessions, despite having met them many times."  A lack of facial recognition of some experimenter is not at all adequate evidence for an inability to form new memories. You could only demonstrate an inability to form new memories by conducting the most careful series of tests and documenting the exact responses given during such tests; and the authors have failed to do any such things. 

We should never trust any scientist making a claim about a lack of autobiographical memory or an inability to form new memories unless such a claim is thoroughly documented by a presentation of the exact results of a very careful series of tests designed to demonstrate such claims. Nothing like that has occurred in this case. 

The Myths About Patient K. C. and Patient H. M.

A recent National Geographic article has an interview with Harvard scientist Daniel Schacter, who is identified as a "cognitive psychologist," an unfortunate term making an unnecessary use of the word "cognitive," rather like calling someone a specialist in numerical mathematics.  The article is on the topic of memory, and  nothing Schacter says explains any neural basis for memory.  But Schacter does reiterate one of the unfounded myths of neuroscientists and psychologists, the claim that a patient K. C. (Kurt Cochrane) could not recall any of his episodic memories from before a brain injury.  "It's fair to say that he could not remember a single specific episode from any time in his life," Schacter falsely states. The facts do not support such a claim. 

Patient K.C. had three brain injuries. At age 16 a bale of hay fell on his head. He had another brain injury in young adulthood, one not causing a loss of consciousness. These injuries seemed to have caused no cognitive problems. But he then had a motorcycle accident at age 30, which seemed to be followed by memory difficulties. According to the paper here, "His brain lesions include almost complete obliteration to the right and left hippocampi and extensive atrophy of his left and right parahippocampal gyri (more pronounced on the left)."

Even after all this brain damage, his recognition memory seemed preserved, because a paper on patient K.C. says, "Upon his transfer to the rehabilitation hospital, K.C. was noted to be reading and conversing quite well and began to recognize friends."

There seems to have been no big loss of conceptual memories or learned knowledge in patient K.C. A paper on patient K. C. ("The case of K.C.: contributions of a memory-impaired person to memory theory") says this:

"Retention of the many skills and semantic facts learned in pre-accident years enables K.C. to locate without difficulty cereal and eating utensils in the kitchen, to know that the eight-ball is the last to sink in a game of pool, and to explain the difference between a strike and spare in bowling, and between the front crawl and breast stroke. He can describe the layout of his house and summer cottage, and the shortest route between them, without any recollection of a single event that occurred at either of these places. He expects a new ‘trick’ after four cards are placed in the centre of the Bridge table and anticipates Bob Barker on the 'Price is Right' asking contestants to 'spin the wheel,'  though he cannot foresee what he himself will do when the card game or television show is over. Like many individuals suffering from amnesia, he is also able to learn new information or skills normally, such as sorting books according to the Dewey decimal system in his library job, even though he is unable to recall explicitly the circumstances of this anterograde learning, indicating preserved implicit memory."

Note the observation defying neuroscience dogma. Countless times neuroscientists have made the groundless claim that the hippocampus is vital for forming new memories. But this patient K.C. with "almost complete obliteration to the right and left hippocampi" was able to "learn new information or skills normally." 

The same paper claims that other than weaker performance in episodic memory, patient K. C. had pretty normal cognitive skills, and a normal intelligence. We read this:

"As illustrated in Table 2, results from cognitive testing show that K.C.’s intellectual and cognitive function outside the domain of episodic memory are largely, although not completely, preserved. His verbal IQ on the revised version of the Wechsler Adult Intelligence Scale (WAIS-R; Wechsler, 1981), as administered in 1996, was in the normal range, and his performance IQ was in the lower normal range, which is slightly below expected based on a verbal estimate of premorbid intelligence derived from the National Adult Reading Test (Ryan & Paolo, 1992). Nonetheless, on the Wechsler Abbreviated Scale of Intelligence (Wechsler, 1999) administered in 2003, which produces IQ scores that are highly correlated with those from the full WAIS-R battery, he obtained Full-Scale, Performance, and Verbal IQ scores of 99."

What does the paper tell us about K.C.'s episodic memory? The paper gives us some claims on this topic that contradict other things the paper says. On one hand the paper says, "What makes him different, even from many amnesic cases, is his inability to recollect any specific event in which he himself participated or any happening that he himself witnessed." But in other places the paper gives us data contradicting such claims.  

The paper gives us this data for tests of patient K.C.'s retrograde memory (memory of the past):

Retrograde memory 

AMI autobiographical (/9) 

Childhood 2 

Early adult life 3 

Recent life 1 

AMI personal semantics (/21) 

Childhood 16 

Early adult life 13.5 

Recent life 8

The references to AMI are references to the Autobiographical Memory Interview. According to the web site of the American Psychological Association, this AMI is "a semistructured interview designed to assess memory for autobiographical information, impairment of which is often indicative of retrograde amnesia (inability to recall previously learned information or past events) and potentially associated with a variety of neurological and psychiatric disorders."

The paper here tells us more about this AMI test:

"Personal semantic questions. Subjects were asked questions relating to their personal past, including names and locations of schools attended, home addresses, and names of friends. Each time period had a maximum score of 21 points. 

Autobiographical incidents questions. Subjects were asked to relate incidents that occurred during each of the three time periods and to give temporal and spatial contextual information for each incident described. Three such incidents were probed for each time period, and specifications such as “first day at work” were used as probes. Responses were recorded on the scoring sheets as close to verbatim as possible. Each incident was scored out of a possible score of 3, based on the descriptive richness and specificity in time and place of the response. The maximum score per time period was 9."

We should be suspicious about the reliability of scores given using this test, because the underlined line indicates a subjective type of rating, in which someone rating and familiar with a person's brain damage might be more more likely to assign lower scores, even when someone performs as well as control subjects. 

A look at some of the questions asked on the test indicate that they can be pretty hard, such as asking the birthday of relatives or the address of previous schools. 

Now, patient K.C. had no major memory problem until his injury at age 30. So the results listed above very much defy and contradict the paper's claim that patient K.C. had "an inability to recollect any specific event in which he himself participated or any happening that he himself witnessed." And the results listed above very much contradict Schacter's claim that patient K.C. "could not remember a single specific episode from any time in his life." The test scores above indicate very substantial episodic memory of K. C. regarding the recall of events from both the childhood and early adult stages of his life. 

In the paper we have this claim, in which the second claim contradicts the first: 

"During testing, K.C. could not produce a single episode from his past that was distinct in time and place. Performance on the personal semantics subsections was comparable to that reported by Kopelman et al. for other amnesic patients, with the childhood period classified as ‘acceptable’ according to AMI norms."

There are several questions we should ask about the first sentence in this statement:

(1) Was this first sentence a reference to merely a single testing session in which K.C. failed to recall something in his past when asked to do so only once -- or maybe a few such failures in a few such tests? If so, that is not any good evidence of an inability to recall an episodic memory from childhood or early adulthood. You might ask someone during one testing session, "Please recall an incident from your childhood or early adulthood." The person might lazily say, "Nothing comes to mind." But if the test is repeated a few days later, the patient might be able to recall several or many such incidents. 

(2) Did the patient actually recall events that happened in childhood and early adulthood, but were such recollections arbitrarily ignored because they were not regarded as sufficiently "distinct in time and place"?

We do not know the answers to these questions, so we do not know whether the claim that "K.C. could not produce a single episode from his past that was distinct in time and place" is an extremely misleading claim, based on a single testing session, or based on an unreasonable exclusion of recollections because of some arbitrary decision that the memories were not "distinct" enough. Notably, the statement "the childhood period classified as ‘acceptable’ according to AMI norms" dramatically contradicts claims that patient K.C. had no episodic memories from his childhood. 

We then read this, about an episodic memory test given patient K.C. in 1996:

"K.C. showed a similar pattern of deficit on the Galton–Crovitz task for autobiographical information, which was administered in the version developed by Moscovitch and Melo (1997). His performance improved only minimally when he was provided with additional prompts aimed at facilitating recall." 

Very suspiciously, we are not given any details of the exact score on this test. We merely hear of "a pattern of deficit," a phrase which does not at all explicitly mention a very low score. And we are told that the performance improved later. 

This is all extremely suspicious. We must suspect these authors of withholding very relevant information that contradicted their claim that patient K.C. had an "inability to recollect any specific event in which he himself participated or any happening that he himself witnessed." Why are no specific test scores given for this Galton–Crovitz test taken by Patient K.C? Probably because the numbers contradicted the claim that patient K.C.  had an "inability to recollect any specific event in which he himself participated or any happening that he himself witnessed."

Later in the paper the authors make statements that dramatically contradict their earlier claim about patient K.C.   We read this:

"To do so, we used a formal autobiographical interview requiring generation of personal events from different life periods under varying levels of retrieval support (Levine, Svoboda, Hay, Winocur, & Moscovitch, 2002). Similar to results from earlier testing of free recall (Tulving et al., 1988; Westmacott et al., 2001), K.C. was unable to produce a single personal story from any time in his life, however remote the episode. Importantly, with supplementary retrieval support in the form of specific cueing, K.C.’s performance continued to remain well below control levels (see Fig. 9), which contrasts with that of patients with frontal lesions who benefit significantly from cueing (e.g., Svoboda et al., 2002). Even those events that K.C. was able to generate with fairly rigorous verbal prompting were without the richness in episodic detail typical of the personal incidents recalled by control participants."

So, aided by a bit of cueing, which might be something like "did you ever miss a day from school from sickness" or "did you ever learn how to swim," patient K.C. was apparently able to remember pretty well events from his childhood and early adulthood.  We have this diagram (Figure 9), which clearly shows that patient K.C. could remember very many details of things that happened to him in his childhood and early adulthood. I have compacted a horizontally larger diagram to make it easier to read. 

The diagram disproves the paper's earlier claim that patient K.C. had an "inability to recollect any specific event in which he himself participated or any happening that he himself witnessed." The diagram shows K.C. recalling many details from before his accident at age 30. Later the very careless paper authors claim that "K.C. has no episodic memory whatsoever for autobiographical details, whether experienced long ago or in more recent times."  Their own graph shows the untruth of this statement, for their Figure 9 is charting that patient K.C. could recall such details. 

A 2006 paper ("Hippocampal Contributions to Recollection in Retrograde and Anterograde Amnesia") gives a diagram on episodic memory tests on patient K.C.  We have the diagram below. The "Ch." stands for childhood; the Ado. stands for adolescence; and the AE stands for "adulthood, early."  These are different periods of his life K.C. was being asked about. We clearly see that patient K.C. could recall details about events that had happened to him before his brain injury at age 30. He simply recalled fewer details than average people (designated below as controls). 

How can we explain these severe discrepancies in the paper on patient K. C. ("The case of K.C.: contributions of a memory-impaired person to memory theory"), the fact that it says things in one place that contradicts the data it gives elsewhere (and data gathered by others on this patient K.C) ? Being charitable, and trying to avoid the idea that the authors were simply lying, we can explain the discrepancy by simply supposing that the authors were guilty in places of very careless language prone to give someone the wrong idea.  Having a mere observation that in one or two tests patient K.C. did not provide an episodic memory when asked to do so, the authors seem to have carelessly stated this as the claim that the patient could not provide such a memory. 

It is all too easy to imagine how something like that could have happened. There could have occurred something like this:

Doctor: Now, could you recall some event from your childhood. 

Lazy or Unmotivated Patient: Uh, let me see...hmm, my mind's a blank.

Doctor: Oh, very interesting! I will write down "Patient could not recall any episodic memories."

But a "did not" never proves a "could not." There are 101 reasons why someone may fail to do something that he is capable of doing, when asked to do it. I once got a perfect score on the CLEP test of American History. But if you ask me to describe the 1880's in the US, I might well say something like, "My mind's a blank." However, given sufficient motivation, such as a $1000 reward, I could probably recall quite a few details about such a decade. 

Below is a a very important rule involving research on memory and amnesia:

***************************************

ONE OR TWO CASES OF "DID NOT" NEVER PROVES "COULD NOT"

***************************************

What happened, I think, is that the authors of the paper on patient K. C. ("The case of K.C.: contributions of a memory-impaired person to memory theory") were simply guilty of very careless language. All that they had in regard to patient K.C. was a "did not" when he was asked to recall some particular episodic memory. There was never any justification for concluding that he could not recall any memory from before his final accident. Other data mentioned above suggests that he could do such a thing. And there was never any motivation factor that would have justified a "could not" conclusion about an inability to recall any episodic memory. No one ever gave the patient a strong motivation to engage in some memory retrieval exercise that he might have found burdensome. 

What we must always remember is that those promoting "brains make minds" dogma and "brains store memories" dogma tend to be "give me an inch, and I'll take a mile" kind of people when it comes to arguing for their cherished beliefs. Most claims that they make about amnesia should be treated with suspicion. A neuroscientist may use the term "amnesia" for any type of shortfall on memory performance tests, which might sometimes occur for reasons other than memory deficits, as illustrated in the visual below, in which apathy is misidentified as amnesia. 

At the links below you can watch interviews with patient K.C. (Kurt Cochran), which occurred in 1988, when he was 38 years old.  You may not even notice any difficulty in his mental abilities. 

At the first link here, K. C.  is asked about how long he has lived in his house, and he answers since 1960, apparently a correct recall involving personal memory. He is answered some general knowledge questions, and answers most of them correctly. When asked about whether he owned a motorcycle or a car, he says he owned both of them, apparently a correct recall of his experience before his injury in a motorcycle accident. Asked about the make and color of his car, he answers a brown Honda. He correctly describes how to change a flat tire. In the second video here, he shows good short-term memory, repeating series of digits he is asked to repeat. In the third video here, he shows a moderately good ability to define words that are recited to him, and does moderately well on an ability to recall words that were recited to him. The fourth video has him answering two math problems well. 

In the fifth video, K. C. is shown a report he made at a job he had, which he seems to correctly identify. He is asked to describe a place he worked at, and he says it was a big two-story building. He recalls using the back entrance of the building. Asked to recall any of his co-workers who worked with him at the building, he says, "Not offhand." But then a few seconds later, around the 3:40 mark, he does name someone who worked with him in the building, an old person named John, who he says was "almost my boss." Then at the 3:52 mark K. C. is asked to identify a person who shared his office, about his age, who did the same thing he did. Around the 4:00 mark, K. C. identifies the person as Chris, also giving his last name. "Yes, very good," says the interviewer, who apparently knew that this was the correct answer. 

Here is that fifth video:

Assuming a lack of any deliberate lie by him, it is obvious that Harvard scientist Daniel Schacter did not watch these videos or did not watch them carefully. The videos clearly show Schacter's was very badly misinforming us about K. C. when he stated, "It's fair to say that he could not remember a single specific episode from any time in his life."

After watching these videos, showing fair performance on every main  type of memory, we should be suspicious that the low scores in the tests listed above were probably due to biased judgments of score raters, who knew beforehand of K.C.'s brain injuries, and who were biased judges motivated to give him low scores, to help sell a loss-of-memory-by-brain-damage narrative. If there had been judges "blind" as to his brain condition, such scores might have been much higher.  Tests of short-term memory offer little opportunity for distortion by biased judges. There is no subjectivity in rating whether a person did or did not recall a word or number you asked him to recall. Conversely, scientist appraisals of the strength of episodic memory are very subjective things, involving subjective ratings of things such as "level of detail" and "vividness."  With such a thing there is ample opportunity for rating bias in which the reported effects are largely scientists seeing whatever they were hoping to see. 

Another false claim frequently made by neuroscientists and psychologists (and writers about neuroscience) is the false claim that patient H.M. (Henry Gustav Molaison)  "could not form new memories" after having some experimental surgery in 1953.  That is not correct.

A 14-year follow-up study of patient H.M. (whose memory problems started in 1953) actually tells us that H.M. was able to form some new memories. The study says this on page 217:

"In February 1968, when shown the head on a Kennedy half-dollar, he said, correctly, that the person portrayed on the coin was President Kennedy. When asked him whether President Kennedy was dead or alive, and he answered, without hesitation, that Kennedy had been assassinated...In a similar way, he recalled various other public events, such as the death of Pope John (soon after the event), and recognized the name of one of the astronauts, but his performance in these respects was quite variable."

Another paper ("Evidence for Semantic Learning in Profound Amnesia: An Investigation With Patient H.M.") tells us this about patient H.M., clearly providing evidence that patient HM could form many new memories:

"We used cued recall and forced-choice recognition tasks to investigate whether the patient H.M. had acquired knowledge of people who became famous after the onset of his amnesia. Results revealed that, with first names provided as cues, he was able to recall the corresponding famous last name for 12 of 35 postoperatively famous personalities. This number nearly doubled when semantic cues were added, suggesting that his knowledge of the names was not limited to perceptual information, but was incorporated in a semantic network capable of supporting explicit recall. In forced-choice recognition, H.M. discriminated 87% of postmorbid famous names from foils. Critically, he was able to provide uniquely identifying semantic facts for one-third of these recognized names, describing John Glenn, for example, as 'the first rocketeer' and Lee Harvey Oswald as a man who 'assassinated the president.' Although H.M.’s semantic learning was clearly impaired, the results provide robust, unambiguous evidence that some new semantic learning can be supported by structures beyond the hippocampus proper."

Neuroscientists have no understanding of how a brain could store or preserve or retrieve memories, and they lack any credible theory on such things. Microscopic examination of brain tissue has occurred endless times from endless subjects, with the tissue often coming from just-died people or people living. Although involving the most powerful telescopes such as electron microscopes, such examination has never provided the slightest trace of learned information stored in brains, and has never provided the slightest indication that there exists any system for translating episodic memories or learned knowledge into brain states or synapse states. 

So what do you if you are someone trying to convince people that brains store memories? Again and again, such writers will follow the same deceptive pattern. Typically a writer will claim that we know brains store memories because you need a hippocampus for memory. This is despite very much data showing that claim is not true, and that people with a very badly damaged hippocampus often perform very well on memory tests.  The writer will typically offer as his proof the untrue assertion that patient H.M. had a damaged hippocampus, and could not form new memories. The quotes above show that assertion is false; patient H.M. could form new memories and could learn new things. 

Of course, such writers will never mention the fact that patient K.C. had hippocampus damage just as bad or worse than that of patient H.M, and that patient K. C. had no big impairment in his ability to learn new things.  Referring to patient K.C. we read in the paper here, "His brain lesions include almost complete obliteration to the right and left hippocampi and extensive atrophy of his left and right parahippocampal gyri (more pronounced on the left)." The same K.C. according to the paper here  was able to "learn new information or skills normally." 

Never forget that the literature of neuroscience and psychology is abundantly infested with false statements, and that there are extremely many types of false statements about brains, minds, memory and particular patients, false statements that are endlessly repeated. 

Postscript:  

According to the page here, someone writing a book about neuroscience professor Suzanne Corkin (a researcher of patient H.M.) stated that Corkin told her she was in "the process of destroying all original notes and records regarding his case." We can only wonder what the motivation for that was -- was it a case of trying to cover up misconduct in describing the case of patient H.M. ?

The recent article here documents another myth of neuroscience literature involving a particular person: the case of Phineas Gage. In the 19th century Gage suffered an accident in which a thick railroad spike was driven through his skull. He seems to have suffered no permanent damage from this huge brain injury.  But for many years people have passed false tales claiming Gage's judgment was badly damaged. The article states this:

"The available facts about Gage fly in the face of claims made about his transformation and reduced capacities. Macmillan gave a carefully sourced description of the demanding nature of Gage’s job in Chile: the dependability required of him in rising in the small hours, loading passengers’ luggage and possibly handling fares; the high level of dexterity and sustained attention necessary for driving six horses; the foresight and self-control involved in navigating the unwieldy coach along the crowded and sometimes treacherous Valparaíso-Santiago road. He also pointed out that Gage, at first a stranger to Chile, would have had to learn something of its language and customs and ‘deal with political upheavals that frequently spilled into everyday life’. "

 The article makes clear that no statements on Gage should be trusted unless they come from the nineteenth century, and that the statements about Gage's behavior made in that time are so scant that there is no good warrant for the claim that Gage's judgment or intellect was damaged. One of the 19th century sources says that friends of Gage said he "was no longer Gage," but second-hand testimony like that (one person saying that other unnamed persons said something) should not be highly trusted. The article documents cases of claims about Gage having no basis in sources from his time, cases of embellishments (fictional claims) that were then repeated over and over again by different writers. 

The article says this:

"When discussing social disinhibition, most researchers cite cases in addition to Gage, but very few miss out Gage. His was the story that started off the whole idea and has remained by far the most frequently referenced, both in the clinical literature and in wider English language publishing. Given just how weak the evidence of his disinhibition really is, this level of reliance on his case seems astonishing."

Gage's injury (link)

Searching Hard for Evidence of Strokes Causing Loss of Episodic or Conceptual Memories, They Come Up Short

The word "amnesia" is what you can call a "loaded" word. When a person thinks of amnesia he may think of some movie or TV show in which a person asks "who am I" and seems not to be able to remember who he is. But the term "amnesia" is defined as "a total or partial loss of memory."  Total memory loss is virtually never reported in the literature.  Almost always when people use the word "amnesia" they are talking about some memory difficulty that is much smaller than total memory loss.  

One of the most common forms of amnesia is what is called transient global amnesia. During an episode of such amnesia, a person may not recognize how he got to his current location. The person may repeatedly ask the same question, as if his ability to learn is temporarily blocked. Symptoms typically last  less than 24 hours, with complete recovery. It is interesting that transient global amnesia is not usually associated with any kind of brain injury. The cause of transient global amnesia is unknown. 

The medical literature reports two more long-lasting types of amnesia: retrograde amnesia (involving a problem in accessing already-formed memories) and anterograde amnesia (involving a problem in forming new memories or learning or memorizing).  Although many people define "retrograde amnesia" as an inability to access old memories, all or almost all case reports of such a thing are something much less than a complete inability to access old memories. In fact, the term "retrograde amnesia" is loosely used to describe all kinds of cases in which someone is slow or imperfect in accessing old memories or previously acquired knowledge.  So when you hear a claim of "retrograde amnesia," it is typically something much, much less severe than the way such a term is commonly defined.  Similarly, the term "anterograde amnesia" is loosely or carelessly used for a wide variety of learning or memorization shortfalls. So typically when such a term is used, someone is talking about a problem much less severe than a complete inability to form new memories. 

A group of scientists tried hard to get evidence that strokes can cause amnesia or memory loss. We read about the technique they used:

"The Medline database was searched through 2017 by combining the search terms 'stroke,' or 'cerebrovascular,' or 'ischemia,' or 'hemorrhage,' with the terms 'amnesia,' or 'memory'. The criteria not 'subarachnoid,' not 'dementia,' not 'cardiac arrest,' not 'transient global amnesia' were also added and search returns were limited to human studies. This search returned 4855 possible matches. These returns were limited to English language articles, and the titles of 1000 papers most related to the search criteria were reviewed, identifying the most relevant 500 papers. These abstracts were reviewed, identifying the most relevant English language papers. Abstract review looked for articles on human studies, primarily about a patient with memory loss, memory loss acquired by a lesion, and the etiology was not transient global amnesia, not Alzheimer’s disease-related, and not a brain tumor or other non-acquired lesions. From this set, we reviewed 250 full-text articles and included reports that fit the following criteria: (1) Case report format or individual case description; (2) Adult population; (3) Clinically relevant episodic memory deficits by bedside or neuropsychological tests attributed by the authors to an acute brain lesion; (4) Availability of a CT or MRI image depicting the lesion location(s) of sufficient quality that the lesion could be transcribed onto a standard brain template (Supplementary Fig. 1). Fifty-three cases of amnesia were found with identifiable causative brain lesions (mean age 57.5 ± 13 years, range 27–72, 66% male). '

To get a list of the 53 papers, you must consult Table 1 of the Supplemental Information part of the paper, which can be read here.  At the end of the table listing the papers, we read this:

"References for the 53 case studies meeting inclusion criteria for our analysis, taken from 50 unique journal articles. All 53 lesion cases were classified as “severe” amnesia (the memory deficit was clinically apparent even without formal neuropsychological testing), involved anterograde memory loss, and included documented impairment in verbal memory. 30/53 cases reported a formal measure of amnesia severity, but the metrics varied. The most common metric was the Weschler Memory Scale general score (13 cases) followed by Cambridge Cognitive Examination memory score (five cases). Only nine cases provided both a Wechsler Memory Scale  general score and IQ score to allow for the calculation of a WMS discrepancy score. 19/53 cases reported whether there was some element of retrograde amnesia: 18/53 reported impairment while one reported that retrograde memory was intact. Only one case reported a score for retrograde amnesia via neuropsychological testing. 20/53 cases reported whether visual memory was impaired, all 20 of which reported impairment. Seven cases reported formal scores for visual memory impairment using the Benton Visual Memory Task. Finally, other characteristics of amnesia were rarely reported such as impairment in semantic memory (four cases), autobiographical memory (two cases), or temporal order memory (one case)."

The confession at the end is interesting. The authors confess that they found almost no evidence of semantic memory being disturbed by strokes, and almost no evidence of autobiographical memory being disturbed by strokes. That is not something we would expect under the hypothesis that memories are stored in brains. Under such a hypothesis you might expect to very often hear of someone whose autobiographical memories were damaged after he had a stroke. 

Below is a table I made discussing some of the cases listed in Table 1 of the paper, as many as I can find.  I may note that many of the titles and quotes use inappropriate adjectives and nouns.  A neuroscientist wishing to maximize his chance of getting a paper published may tend to use the word "amnesia" for something that is a mere performance shortcoming, and may also use the word "severe" to describe something that is not very severe at all.  The more dramatic the report sounds, the higher the chance will be that the paper will be published, to the benefit of such a neuroscientist.  We must remember that scientists live in a "publish or perish" culture in which it is as if the key goal of their lives is to get as many papers published, with as many citations as possible.  In such a culture exaggeration is to be expected. In fact, in today's world of neuroscience it is massively common for papers to have titles that do not accurately describe the research findings made, and it is also massively common for papers to have claims in their abstracts that are not justified by any findings reported. 

In quite a few of the cases I will discuss below,  amnesia or "amnesic syndrome" is claimed, but inadequate evidence is given for such a claim. You can only reliably verify a claim of long-lasting amnesia by careful tests done on multiple days. There are any number of short-term reasons why a person might perform poorly on some quick memory test on a particular day. The person might be distracted or indifferent or in pain or not paying attention or in a foggy state of mind.  So, for example, the fact that a patient is asked to repeat words he was told to remember (after a gap of five minutes) is no strong evidence of "anterograde amnesia."  There are any number of reasons why someone might say "I don't remember" when asked to remember something like words he was told to remember five minutes ago, or asked for the names of the presidents before the current president. Explanations such as lack of effort or indifference or distraction (extremely common effects) are the most plausible explanation for such failures rather than the exotic explanation of stroke-produced amnesia. The visual below illustrates the point:

Here is the table showing the papers from Table 1 of the paper mentioned above. I omit almost all papers that were behind paywalls, making it too difficult to find the relevant details. 

Paper	Description	Comment
Amnesia after a discrete basal forebrain lesion	A man had surgery for a 5 mm. aneurysm in his brain. "Immediately after the surgery, he developed disorientation and agitation."	Although the man's state is  described in the paper as amnesia, nothing very serious-seeming is described.  We hear vague mentions of "difficulties" without much in the way of specifics.
Teaching NeuroImages: amnesia due to fornix infarction	We hear vaguely of "acute confusion and short-term memory difficulties, including significant retrograde and anterograde amnesia," but get no specifics.	The abstract fails to convincingly link this case to any brain problem. We hear a claim that "small vessel disease" was "the most likely cause," but no evidence to support that claim.
Clinical Reasoning: A puzzling case of amnesia	A woman "could not recall events that occurred in a 2-week period surrounding neurosurgery."  Since that sentence does not use "any events," we do not know how serious a memory difficulty was involved.	We get no specifics documenting that any real amnesia occurred.   The report is too vague to conclude that amnesia really occurred to any large degree.
Fractionation of memory in medial temporal lobe amnesia	We hear of a patient RH with mild memory difficulties and a patient JC with poor visual and verbal recall,  Regarding Patient RH, we read, "the volume of her right hippocampus was 58.6% smaller than her left hippocampus." Patient RH "with selective right hippocampal damage, performed well on several verbal memory tests and her estimates of recollection and familiarity for words were normal." But "RH’s performance on standard tests of prose recall and a test of delayed recall for names was poor."  We read, "RH performed normally on tests employing human faces."  But "the bilateral hippocampal amnesic, JC, showed a profound verbal memory impairment."	Neither of the cases is  amnesia according to common understanding of the word.  We seem to have learning difficulties related to speech, visual perception or language processing.  Although we are given evidence Patient RH had brain damage, we are given no convincing evidence that Patient JC had any brain damage.  The paper claims that JC had "bilateral hippocampal damage" but provides no compelling evidence to back up such a claim, and we are told his  "neurological examination was unremarkable," contradicting such a claim..
Pure amnesia after unilateral left polar thalamic infarct: topographic and sequential neuropsychological and metabolic (PET) correlations	15 days after experiencing severe turbulence on a flight, a woman admitted to a hospital was "unable to recall her profession." "During the first few days, she was slow, easily tired, and disoriented in time, but she always knew that she was in a hospital and found her way around easily. Her behaviour and contact with the examiners was always adequate. Spoken and written language, praxias, visuocognitive functions, and spatial orientation were largely preserved.... with the exception of difficulties in naming objects and people." "Memory testing ... revealed sparing of short term memory and preserved learning of new skills, but major deficits in episodic memory and in acquisition of new material. The latter deficit was always more severe for verbal than non-verbal material." "The patient read fluently and, 4 months after the onset of the illness, was able to recall a read story."	Despite the "pure amnesia" in the title, the evidence prevented for memory dysfunction is spotty.  We read of a small one-centimeter lesion found in the patient's brain, but we don't knew whether this was the cause of her problem.  Some of the trouble might be related to psychological trauma from the flight turbulence.
"Frontal Verbal Amnesia"	A man "noted the sudden onset of difficulty in speaking and weakness of the right side of his body."  "The patient performed normally on a wide range of language tasks and exhibited a normal verbal IQ. In spite of his at least relatively normal language skills, however, he has a marked verbal memory deficit with sparing of nonverbal memory."	It seems misleading for the authors to have called this case "amnesia." The dysfunction documented is very limited.
"Cognitive disconnective syndrome by single strategic strokes in vascular dementia."		Six cases are described in too sketchy a manner for one to draw any conclusion about memory effects of a stroke.
"Amnesia following thalamic hemorrhage. Another stroke syndrome"	"Results of standard psychometric tests indicated above-average intellectual ability. On the Weschler Adult Intel1igence Test his verbal IQ was 111, performance IQ 108, and full-scale IQ 110. No obvious verbal performance discrepancy was present, but administration of the Weschler Memory Scale yielded a memory quotient below normal and impaired ability for new verbal learning." The patient soon died.	Another case of the inappropriate use of the word "amnesia" for mere sub-normal test performance.  No evidence for amnesia is documented.
"Memory loss from a subcortical white matter infarct."	"He was able to repeat four numbers forward, could not recall any of three objects after 3 minutes, but was able to remember recent presidents. Spontaneous speech was grammatically correct with mild hesitancy on initiation of sentences and a tendency towards echolalia. Repetition, naming, reading and writing were all preserved. Verbal comprehension was mildly impaired only when dependent upon understanding complex syntactic relationships. Finger naming, right/left orientation and calculations were normal. Visual-spatial testing of spontaneously drawn and copied figures was normal. ... Neuropsychological assessment included Form I of the Wechsler Memory Scale. Despite scoring nearly flawlessly on the personal information (6/6) and orientation (4/5) subtests, the patient only recalled 4/24 and 2/22 memories from the logical memory subtest (about 2 SD below that expected for his intelligence and age).... In contrast, nonverbal memory function was less affected, as shown by his visual reproduction subtest score (4/14), only 1 SD below mean."	Another misleading paper title. After an apparent stroke, the subject seemed to have only a minor performance defect in memory tests.
"Bilateral hippocampal infarction and amnesia:A case report"	"The mild confusion was present in the form of constant repetition of the same questions as well as the temporal and spatial disorientation." But the patient scored 23 and three months later scored 25 on the MMSE test, the second score requiring fairly good memory (a score of 26 being normal). And the patient scored normally on a Digits Span Forward memory test and  Digit Span Backward memory test.	The paper claims "Severe anterograde amnesic syndrome, related to the domain of episodic memory, dominated," and claims that "the patient was unable to recall any of the previously presented information."  The claims are not backed up by robust evidence, and are contradicted by the MMSE scores given and the Digit Span scores given.
"Acute bilateral thalamic infarction as a cause of acute dementia and hypophonia after occlusion of the artery of Percheron."	No claim of amnesia is made, and no proof is given that the patient suffered from dementia. We merely read the hesitant claim that "after all these tests and the total clinical assessment of the patient, thalamic dementia was under a reasonable consideration."	No evidence is given for amnesia, and the only evidence given for dementia is a single MMSE test with a score below 18.
"Where am I?’ –An unusual stroke presentation"	We read of a man who had a stroke, and we hear the claim that he "he had no recollection of events of the past decade." Since this statement does not contain the word "any" we have no idea of how bad the memory problem was.	The paper is a very short one, and we have no specifics of memory tests. So it is unclear how bad this person's memory problem was. It is also not clear that stroke caused any memory problem the man had.
"Retrosplenial amnesia without topographicdisorientation caused by a lesion in the nondominanthemisphere"	An old man had "normal remote memory," and the claim is made he had trouble navigating in the hospital because of "amnesia."  We have the claim that "he could not learn the disease name, patient room number, and the primary physician's name, suggesting mainly anterograde amnesia." But no proof is provided for such a claim.	There could be details supporting the claim of anterograde amnesia, but none are found outside of a paywall. We don't know whether other issues might have caused the patient to fail to learn the items mentioned.
"The paramedian diencephalic syndrome: a dynamic phenomenon"	We read of an attorney who had a variety of problems after a heart operation. We hear of a downward gaze, lack of attention to doctors and confabulation. and we get a vague reference to "amnesic syndrome."	We don't get specific details about memory loss. We read that the patient did well on "repetition" and "naming," and that on reading and writing his performance varied from normal to grossly deficient.
"Migrainous stroke causing thalamic infarction and amnesia during treatment with propranolol"	We hear a claim that a patient  "had significant confusion and amnesia."  But we get no details backing up that claim, and no mention is made of a chronic memory problem.
"Amnesia due to fornix infarction"	We hear that a 71-year-old with brain lesions had " anterograde amnesia for verbal and visual information,"  although we don't hear of much to support that claim.  We read, "Her immediate memory for the Rey-Osterreith Complex Figure... was at the first percentile, and after a delay, it was nonexistent. Her performance was average on the Boston Naming Test and Wisconsin Card Sorting Test."  We read, "On the follow-up visit 1 month later, she showed significant improvement in her short-term memory. She was able to recall 3 objects after 5 minutes and displayed marked progress in her ability to register verbal and visual information. However, she had no recall of the events of her hospitalization."	No evidence has been given here of serious amnesia, other than forgetting events of a hospitalization.
"Amnestic Syndrome of the Subcallosal Artery: A Novel Infarct Syndrome"	The paper is half-way behind a paywall. The part we can read makes no mention of loss of episodic or conceptual memories, but merely claims "severely impaired recall of both verbal and visual information," and mentions an inability to recall three words after three minutes.
Unilateral Amnesic Stroke	The paper confesses "reports of amnesic syndromes due to unilateral stroke have appeared infrequently and unsystematically." It presents six cases it claims are examples of "amnesic stroke." No evidence is presented of any serious long-lasting amnesia in any of the six patients.  We merely hear spotty reports of imperfect performance on some memory tests (such as remembering 3 words after 3 minutes, but not after 5 minutes), and a few anecdotal reports of scattered failures such as a failure to name past presidents.	The authors are using the term "amnesic stroke" without adequate warrant.  The old people described have memory shortcomings common in old people. I may note that failing to name three words you were asked to remember after five minutes is never convincing evidence of memory impairment, unless verified in multiple tests on different days. There are any number of reasons (pain, distraction, indifference, etc.) why a person might not answer such a question at a particular time.
"Bilateral posterior cerebral artery infarction"	Other than mention of confusion upon being admitted to the hospital, we hear mention only of a short-term memory problem, but no specifics.	We have here an example of writers making unjustified use of the term "amnesic syndrome." We read: "There was evidence of a profound amnesic syndrome with impaired delayed recall (0/3 on Mini-Mental State Examination recall). He could not remember why he had been brought to the hospital." The MMSE mention is a mere mention of failing to recall three words you were asked to remember.  There are any number of reasons why a person might fail such a request other than amnesia (distraction, indifference, etc.).  Failing to remember why you were brought to hospital is no strong evidence of amnesia.
Hippocampal Lesion Patterns in Acute Posterior Cerebral Artery Stroke	We have some memory tests on patients who had damage to the hippocampus because of a stroke infarct, who are referred to below as HI patients (hippocampal infarct patients).  We read, "In the MMSE, the patients reached a score of 24.30±3.91 (lying in the mildly impaired range), with no difference between groups, t(18)=1.33, P=0.202. In the Clock Drawing Test, the patients reached a score of 2.84±1.26 (at the border of the normal range), with no difference between groups, t(17)=0.51, P=0.618."  In regard to results of a RBMT test of long-term verbal memory, we read this: "Compared to normative samples, the scores of patients with left HI were within the mildly impaired range, whereas the scores of patients with right HI were only slightly below the mean of the normative sample."	The results defy common claims that the hippocampus is crucial for memory. We have hippocampus- damaged patients who have performed fairly well on memory tests.
"Diaschisis after thalamic stroke: a comparison of metabolic and structural changes in a patient with amnesic syndrome"	The paper wrongly claims it has a patient with "classic amnesic syndrome," but it provides no data backing up that claim. The patient's MMSE score (largely a memory test) was above-average for a patient of her age, and we merely read of a "mild semantic memory disorder."
"Amnestic Syndrome and Vertical Gaze Palsy: Early Detection of Bilateral Thalamic Infarction by CT and NMR."	We read of a 27-year-old acting in a strange and sleepy manner. Her memory performance is spotty. "Long term memory was affected in an uneven fashion. Previous addresses, jobs, and acquaintances were recited accurately, but she was unable to give her phone number, and could not name present or past California governors or U.S. presidents. Digit span, however, was excellent — seven digits forward and five in reverse. Affect was characterized by indifference, facetiousness, and paucity of spontaneous speech."  We are told, "At three months she was felt by friends and family to have entirely recovered, and on neurologic exam was normal."	The case was too short-lived and spotty to be called a serious case of amnesia.
"A case of amnestic syndrome due to right thalamic infarction"	A 66-year-old is described with only minor mental symptoms, and she seems to have near-normal memory performance.  No justification is given for a claim of "amnesic syndrome."
"Preserved complex emotion-based learning in amnesia"	We have a report of an 85-year-old man with some bad memory performance, and we hear that he had a stroke. But there is no evidence given that his bad memory was a sudden result of his stroke. Strangely the same person performed above-average on some memory tasks.	It is well-known that very many very old people have memory problems. The paper does not make clear whether this person's memory problems came on gradually, or resulted suddenly from a stroke.
"Retrospinal amnesia"	We read of a 39-year-old man who was hospitalized with a severe headache. He apparently had some kind of stroke or infarction, and had a brain operation while hospitalized. We read, "All language and language-related functions were intact, as was performance on tasks associated with frontal-subcortical functions (i.e., Verbal Fluency (Benton, 1968; Lezak, 1976), Proverb Interpretations, Stroop, Visual-Verbal Test (Siegel, 1957))." We hear a claim that he had "profound amnesia," but that is followed by a claim that "His remote memory, however, appeared intact, as assessed by the Albert Remote Memory Battery (Albert el al., 1979)."  We hear of poor performance on verbal memory tests asking a subject to remember words and stories, but we are told "he performed much better on nonverbal recent memory tasks."  We are told, "T.R.'s memory deficit was to some extent material-specific. Verbal tasks showed a consistent deficit; while tests of nonverbal memory, except for the Rey-Osterreith Complex Figure Test, were performed normally."  We are told he "he had remarkably intact general intellectual functions.'	The patient seems to have had some brain problem causing some kind of  deterioration in verbal processing.  No very strong evidence has been given of a loss of old  episodic or conceptual memories, other than some scattered anecdotes.
"THE SEPTO-HIPPOCAMPAL PATHWAYS AND THEIR RELEVANCE TO HUMAN MEMORY: A CASE REPORT."	We hear of a young man who went to the hospital with a bad headache, and who then had a brain operation. We read, "Autobiographical memory revealed an almost complete loss of information from the two months prior surgery. Otherwise, major personal events were preserved, although some details, particularly events of the preceding year, were no longer available. His domain-specific (professional) knowledge was by and large spared."  We hear about a low performance in memory tests, but also are cautioned that the patient had low motivation, which might have produced scores lower than could have been produced if he were motivated.
"Diencephalic amnesia and apraxia after left thalamic infarction"	We read of a 78-year-old woman speaking only Hungarian hospitalized in Australia because of strange behavior.  The evidence value of the report is limited by the lack of any test scores, and by the fact that the woman was questioned not directly by the doctor, but through an interpreter, because she spoke a language the doctor did not speak.  We have no idea of how accurate the translation was (presumably those who speak Hungarian are rare in Australia). We read this: " She acknowledged she was in a hospital, but maintained it was in Budapest and the year was 1947. Although her recollections regarding her early life and wartime Hungary seemed accurate, she confabulated when asked for details of recent events." But how long did this strange state last? We are not told. We are merely told that 3 months later the woman still had some kind of memory problem.	The lack of a detailed follow-up report on this strange case is suspicious. We may reasonably suspect that the strange described condition was a short-term thing, and we may wonder whether some glitch in language translation was largely responsible for the strange report. We have no clear evidence of a stroke, but merely read of an fMRI showing something "consistent with a stroke."
"Acute Korsakoff Syndrome Following Mammillothalamic Tract Infarction"	We have this claim about a 56-year-old man: "In addition to anterograde amnesia, he also had retrograde amnesia and could not recall events of the previous 4 years."  The lack of the word "any" in such a sentence leaves it unclear how bad the man's recall of events of the past four years was. The only specifics we are given is the claim that the man did not believe that his father had died, which has occurred two years earlier.  We are told, "The level of general intelligence, previously learned skills, immediate recall, and ability to calculate in short formulae were retained."  We read a claim that the man's memory had not improved 4 weeks later and 8 weeks, although no evidence is given for such claims, except for the claim that the man still did not believe his father had died.	We have no test scores and no specifics to back up the claim of either antegrade or retrograde amnesia, other than a vague statement that the patient "could not recall events of the previous 4 years" without making it clear whether the author meant "any events," and the claim that the patient did not acknowledge his father's death (which might have occurred for any number of reasons not related to memory).  The patient could have had amnesia, but the paper fails to document such a condition in any convincing way.

I must reiterate some important points here:

• Scientists and many doctors live in a "publish or perish" culture in which they are largely judged on the basis on how many scientific papers they have produced, and how many citations such papers have got. In such a situation we should expect for there often to occur exaggerated claims in scientific papers, and that does occur massively. So we should be suspicious of all uses of the word "amnesia" or claims of "severe amnesia" or "acute amnesia," and wonder whether such language has been chosen to maximize the chance of paper publication and paper citation. 
• Extraordinary claims of amnesia require very strong evidence, which is typically lacking in the reports above. 
• It is fallacious to cite a single case of low performance on a memory test as proof of amnesia, as there are any number of reasons other than amnesia why a person might perform poorly on a memory test (reasons such as distraction or indifference or failing to understand the speaker).  Patients often don't understand English well, and doctors often speak English in a thick accent, a factor that by itself can explain poor performance on a verbally-given memory test. 
• You have given no clear evidence of amnesia by a claim such as "the patient could not remember events of the past year," because such a statement (lacking the word "any") leaves it unclear whether the patient could not remember any events or merely could not remember some events. 
• It is usually impossible to tell when a stroke occurred and often impossible to tell if a stroke occurred, so claims of a stroke cause in the cases above are typically questionable, and often involve guesswork.  A paper claiming that brain scan results are "consistent" with a stroke has typically not shown that a stroke occurred, and has not shown that stroke caused the observed memory performance shortfall. 

The end result here is that none of these papers convincingly demonstrate a permanent loss of episodic memories or conceptual memories from a stroke event.  Overall, the results are consistent with the claim that memories are not stored in the human brain.