Surprising Studies on Memory Loss or IQ Changes After Brain Surgery or Brain Damage

Neuroscientists typically claim that memories are stored in the brain. There are some very complex ways and very simple ways in which such a hypothesis can be tested. A very complex way would be to use dissection to see whether any sign of human memories can be found. You could do this in two different ways: (1) by dissecting the brains of people who had recently died, looking for learned information such as facts learned in school; (2) by analyzing tissue removed from the brains of living people, to look for  learned information such as facts learned in school. There are plenty of opportunities for the second of these methods, because brain tissue is often removed to treat diseases such as epilepsy. Sometimes an entire half of the brain is removed in an operation called a hemispherectomy, to treat very severe and frequent seizures. Epilepsy is also treated by less severe operations that involve removing much less than half of the brain. 

Examining removed brain tissue has never produced any support for the claim that memories are stored in brains. No one has ever seen any words or letters by looking at brain tissue through a microscope. No one has ever used a microscope to look at brain tissue of some particular person, and seen images corresponding to sights that person  previously saw. No one has ever seen any sign of encoded information by looking at brain tissue through a microscope,  other than genetic information which is not information that anyone learns through school or experience.  

The method described above is a very complex method that might require the use of very sophisticated equipment such as electron microscopes. But there is a very simple way of testing the hypothesis that memories are stored in brains. You can simply do what may be called a  "loss of learned information" test, testing someone both before and after the person had surgery to remove some of their brain tissue. You can look for loss of memories and learned information that had been acquired before the operation. 

Such a test would be different from a typical memory test. A typical memory test might measure how well someone can remember some new information he was asked to memorize. But a "loss of learned information" test would only test whether something learned or remembered before some brain surgery had been lost by the act of surgery itself. 

You would think that scientists eager to prove their claims that memories are stored in brains would often do such a "loss of learned information" test.  But it seems very hard to find examples of such tests in the scientific literature. 

Let us look at some papers that may be relevant to discussions of whether human brains store memories.  We must carefully distinguish between two types of tests:

(1) A "performance on new learning" memory test will test how well some person can still acquire different types of new memories after having lost some brain tissue.

(2) A "loss of old memory" test will test whether a person lost some memory he had acquired, because of some loss of brain tissue.  

The second type of test is more relevant to whether the brain stores memories.  Removal of some brain tissue might damage your senses or perception in a way that might decrease your ability to learn new things and acquire new memories. But that would not show that your previous memories acquired before such a removal were stored in your brain. Similarly, if you make a person blind, that will reduce his ability to learn, but that does nothing to show that brains store memories. 

We must also carefully distinguish between a random pool of brain tissue loss subjects, and a pool of subjects who have been selected because they showed symptoms of memory loss. I have looked at quite a few papers in which we are told that some pool of subjects was selected for both brain tissue loss and also memory problems. Tests of the extent of memory loss in such persons may be giving a very misleading impression, because only subjects having memory loss were selected for the tests. Such studies may merely show that "people with memory problems have memory problems." 

It seems that our medical professionals are usually bad about testing preservation of memories after doing operations that remove half of a brain or a large fraction of the brain. I think this may be because they do not want to do a test that will produce results that contradict their dogma that memories are stored in brains. But here and there in the scientific literature you will be able to find some tests that serve as tests of how well memories were preserved after half of the brain was removed. In some other cases, we will be able to infer that there was  little or no loss of memories acquired before the operation, either because of a lack of mention of any such thing (which would be noteworthy and worthy of mention if it occurred), or because of some general assurance that the operation usually produced "no serious complications," a claim that should only be made if previously acquired memories were well-preserved.  

Let us look at some of the papers that might be relevant. 

• The paper here ("Unexpected amnesia: are there lessons to be learned from cases of amnesia following unilateral temporal lobe surgery?") tells us that "Cases of amnesia following unilateral temporal lobe surgery are rare." It tells us that "Davies and Weeks (1993) did report one case of postoperative amnesia in a series of 58 cases of unilateral temporal lobectomy, whereas Walczak et al. (1990) found one case of marked deterioration in memory from a preoperative normal state in their series of 100 patients who underwent such surgery." The authors state, "We were able to locate nine definite cases of amnesia following unilateral temporal lobe surgery in the English language literature." But the paper gives us no interesting accounts describing amnesia in any of these cases. We do have a Table 3 that has "before" and "after" columns for seven of the nine cases. The table fails to mention much of anything backing up claims that the patients had amnesia in the sense of loss of memories or learning they had acquired before the surgery. We have "before and after" IQ scores for the first five subjects, which show no significant difference (there sometimes being an increase).  For patient 6 there is no data, and for patient 7 we read "postoperative scores on executive and language function similar to preoperative scores." In the column labeled "Post-surgery memory functioning" we hear of some declines in memory performance tests for some of the subjects, but we hear nothing about a loss of memories that they had acquired before the operation.  And some of the results in that column involve tests taken years after the surgery, so we don't know whether any declines reported were the result of the surgery. In short, the paper fails to provide any good evidence that memories or learned information can be lost by temporal lobe surgery for epilepsy. 
• The paper "Memory outcome after temporal lobe epilepsy surgery: corticoamygdalohippocampectomy versus selective amygdalohippocampectomy" fails to discuss any measurements or observations about how acquired memories or learned knowledge declined after brain surgery that removed substantial tissue. It does tell us that for 63 patients IQ went up by about five points after such surgery, and that for another 60 patients IQ increased by nearly five points. The paper tells us that "General intelligence increases after epilepsy surgery." 
• Almost the same claim is made by the paper here ("Psychiatric and Neuropsychological Problems in Epilepsy Surgery: Analysis of 100 Cases That Underwent Surgery"), which tells us, "The full IQ score of the Wechsler Adult Intelligence Scale–Revised (WAIS-R) was increased after temporal lobectomy in 75% of the cases (p < 0.01; n 4 44)." 
• The paper "Retrograde amnesia in patients with diencephalic temporal lobe or frontal lesions" has some interesting graphs showing memory tests in a group of subjects that included "15 patients with dicephalic lesions, 15 patients with temporal lobe lesions, 15 with frontal lobe lesions and 20 healthy control subjects." We have graphs showing performance on tests that include tests of autobiographical incidents, news recall and famous faces. All of the patients with lesions are able to produce scores ranging from about 70% to 30% of the scores produced by control subjects.  This is not a very impressive result, considering that the paper says, "The patients were selected in all cases on the basis of their having significant anterograde memory impairment in association with clinical and CT scan evidence of pre- dominantly focal lesions in either the temporal or frontal lobes or the diencephalon."  Since both having brains lesions and being not good at remembering the past was a requirement for being chosen in the study, the paper fails to show a link between the lesions and the memory performance. Similarly, if you did a study that only accepted subjects who were both gay and alcoholic, that would do nothing to show that being alcoholic tends to make people gay. 
• The paper "Retrograde amnesia in patients with hippocampal, medial temporal, temporal lobe, or frontal pathology" suffers from the same shortcoming.  We have some graphs showing inferior memory performance on five patients, on tasks of autobiographical recall, recalling famous news events, and recalling famous faces. But the paper eventually tells us that these patients "were selected on the basis of significant anterograde memory loss and MRI evidence that regional brain atrophy was restricted to the medial temporal lobe structures."  So the result merely tells us that people who have trouble remembering what they learned have trouble remembering what they learned. A random sample of five subjects with the same brain tissue loss might tell a very different tale. 
• The paper "Clinical outcomes of hemispherectomy for epilepsy in childhood and adolescence" (about surgeries removing half of a brain) tells us that "the overall developmental/cognitive category was unchanged following surgery in 23 out of 27 children," and that "two children showed a >15 point improvement in DQ/IQ following surgery,"  referring to a substantial increase in intelligence as measured by IQ tests. 
• The paper here "Seizure control and developmental trajectories after hemispherotomy for refractory epilepsy in childhood and adolescence" (in Figure 4) describes IQ outcomes for 41 children who had half of their brains removed in hemispherectomy operations in Freiburg, Germany. For the vast majority of children, the IQ was about the same after the operation. The number of children who had increased IQs after the operation was greater than the number who had decreased IQs. 
• The paper "With childhood hemispherectomy, one hemisphere can support—but is suboptimal for—word and face recognition" involved tests on 15 left hemispherectomy patients, 24 right hemispherectomy patients, and 58 age-matched control subjects. A hemispherectomy typically involves removal of one-half of the brain to stop very frequent epileptic seizures. According to Figure 5, most of the patients who had a hemispherectomy were only "mildly impaired" in their ability to recognize words and faces, with a few being "moderately impaired," a few others having "average" performance, and one having "above average" performance.  The tests performed seemed to have been purely "performance on new learning" tests. We read that "Childhood hemispherectomy patients showed above 80% accuracy on tasks of face and word recognition," and the paper calls this "surprisingly good performance."
• A 2015 scientific paper ("Brain abscess: surgical experiences of 162 cases") looked at 162 cases of surgery to treat brain abscess, in which parts of the brain undergo the cell death known as necrosis, often being replaced with a yellowish pus. The article contains quite a few photos of people with holes in their brains caused by the abscesses, holes in their brains of various sizes. The paper says that “complete resolution of abscess with complete recovery of preoperative neuro-deficit was seen in 80.86%” of the patients, and that only about 6% of the patients suffered a major functional deficit, even though 22% of the patients had multiple brain abscesses, and 30% of the abscesses occurred in the frontal lobe (claimed to be the center of higher thought). Interestingly, the long review article on 162 brain abscesses treated by brain surgery make no mention at all of amnesia or any memory effects, other than to tell us that “there was short-term memory loss in 5 cases.” If our memories really are stored in our brain, how come none of these 162 cases of brain abscesses seem to have shown an effect at all on permanent memories?
• Similarly, a scientific paper ("Brain abscess: clinical aspects of 100 patients") about 100 brain abscess cases (in which one fourth of the patients had multiple brain abscesses) makes no mention of any specific memory effect or thinking effect. It tells us that most of the patients had “neurological focal deficits,” but that's a vague term that doesn't tell us whether intellect or memory was affected. (A wikiepdia.org article says that such a term refers to "impairments of nerve, spinal cord, or brain function that affects a specific region of the body, e.g. weakness in the left arm, the right leg, paresis, or plegia.")   The paper tells us that after treatment “80 (83.3%) were cured, eight (8.3%) died (five of them were in coma at admission), seven had a relapse of the abscess,” without mentioning any permanent loss of memory or mental function in anyone.
• Another paper ("Epidemiology of brain abscess in Taiwan: A 14-year population-based cohort study") discusses thousands of cases of brain abscesses, without mentioning any specific thinking effects or memory effects. 
•  Another paper ("Retrospective analysis of 49 cases of brain abscess and review of the literature") refers to 49 brain abscess patients, and tells us that "the frontal lobe was the most common site," referring to the place that is claimed to be a "seat of thought" in the brain. But rather than mentioning any great intellectual damage caused by these brain holes, the paper says that 39 of the patients “recovered fully or had minimal incapacity,” and that five died.
• A paper tested the ability to recognize faces and words in a group of control subjects and about 39 subjects who had undergone hemispherectomy, typically to remove half of their brains. Most of those who had the hemispherectomy operation performed almost as well as the normal controls.  We read, "This performance level is perhaps surprisingly high, relative to the brain volume resected  [removed] (often close to 50%), hinting at a nonlinear degradation of function with resection. Second, the patients' accuracy was not dependent on the hemisphere removed. That is, the single LH or RH of patients showed comparable performance on face and word recognition."
• The paper "Memory outcomes following hemispherectomy in children" fails to mention in its abstract any loss of episodic or conceptual memories after hemispherectomy operations typically involving removal of half a brain. It says, "Undergoing hemispherectomy was not necessarily associated with declined memory performance, with the majority of patients showing stable scores."
• The paper "The Cognitive Outcome of Hemispherectomy in 71 Children" describes outcomes of operations typically removing half of a brain to stop very frequent seizures. The paper gives us in Table 7 the pre-operation and post-operation IQ scores for 31 different children. The decline in IQ is only small. The children went from an average IQ of  80.5 to an average IQ of 75.7. 26 of these children were given a test called the Peabody Picture Vocabulary Test. For these 26 children the average score increased from 79.0 to 82.1. This test is very important because it is effectively a test of previously acquired knowledge. In the test a person is shown a series of four pictures, and is asked a question such as "Which picture shows laughing?" The test therefore measures previously acquired knowledge. The increase in the score on this test is most remarkable. It is not at all what we would expect if the human brain stores memories. Under the hypothesis that the brain stores memories, removal of half of a brain should cause a sharp decline in performance on this test. Similar results are shown in Table 9. We have pre-operation and post-operation IQ scores for 15 different children (not the ones described in Table 7). The decline in measured IQ is less than a single point. Scores on the Peabody Picture Vocabulary Test rose from an average of 43.0 to an average of 51.7. Another paper summarizes these results by saying, " Pulsifer et al. ... reported cognitive outcomes in 71 children who underwent hemispherectomies and found little changes in cognitive performance pre- and post-surgery."
• The paper "Long-term functional outcomes and their predictors after hemispherectomy in 115 children" did not test for IQ or memory, but reports on things such as speech ability, walking ability and reading ability. We read this: "In this cohort of 115 children, at a mean follow-up of 6.05 years after hemispherectomy, 83% patients walked independently, 73% had minimal or no behavioral problems, 69.5% had satisfactory spoken language skills, and 42% had good reading skills."
• The paper "Hemispherectomy in adults patients with severe unilateral epilepsy and hemiplegia" discusses "25 adults who presented severe unilateral epilepsy and hemiplegia and underwent anatomic or functional hemispherectomy in between 2006 and 2011."  16 of these were "anatomic hemispherectomies" apparently involving removal of half of the brain, and the other nine were "functional hemispherectomies."  Very remarkably, we are told "All of the patients’ postoperative scores of overall QOL, full IQ, verbal IQ and performance IQ improved compared with pretreatment scores."  We don't read anything about before-and-after tests of memory retention, but we read that "Hemispherectomy is a safe operation for epileptic adults with hemiplegia and serious seizures and seldom leads to severe complications."  We may presume that the people having these operations still preserve almost all their memories, seeing that the loss of much of your memories would certainly be a "severe complication." 
• The paper here ("Retrograde amnesia after traumatic injury of the fronto-temporal cortex") tells us of a man who suffered severe brain damage after falling from a horse. He was in a coma for 6 weeks, and his MRI showed very extensive brain damage in multiple areas. The man was given various tests of how good his acquired memories were preserved. He scored 33 out of 60 on the Famous Faces Test, and 70 out of 100 on the Semantic Knowledge Test.  He was able to remember 8 of 16 objects from his past. He scored 100 on an IQ test. Since the test was done four years after the fall, we don't know how much of this decline was caused by the fall. 
• The paper "The Effect of Early and Late Brain Injury upon Test Scores, and the Nature of Normal Adult Intelligence" is behind a paywall. But from the freely available first page we get the interesting information that after searching for IQ scores recorded about brain surgery, the author found 15 subjects, and found that they had an average post-operative IQ of 108.   The author also found another group of 23 brain surgery patients who had an average post-operative IQ of 107. We are told "in none was there postoperative loss" of IQ.
• The paper "When only the right hemisphere is left: Studies in language and communication" reports on the case of a patient BL of "above normal intelligence" who underwent a left hemispherectomy at age five. Despite lacking the left half of his brain, BL "attended regular elementary and high school and graduated from college with a Bachelor's degree with a double major in business and sociology," he "played the baritone horn in a band," and worked "several years as an accountant in international business." The paper reports BL scoring normally on most of the cognitive tests he took.
• The paper "Functional consequences of hemispherectomy" gives us in Table 1 before-and-after IQ scores for 12 children who had half of their brains surgically removed. The worst result was a decline in IQ of 11 points, occurring for only one of the subjects. The best result was an increase in IQ of 8 points, which occurred for three different subjects. Overall, there was more of an increase in IQs than a decrease.  
• The paper "Long-term outcome of hemispheric surgery at different ages in 61 epilepsy patients" examines the IQ effects of removing half of a brain.  Near the bottom of Table 2 we are told that out of 55 patients, only 5 experienced post-surgical "intellectual deterioration," with 50 categorized as "not worse" in regard to "intellectual deterioration." 21 of these 55 patients are called "better" in regard to "intellectual improvement," and 34 are called "not better."  We read, "More than 80% appeared improved or unchanged in intelligence following surgery." We don't hear much specifics on memory, but we get the claim that these "remove half the brain" operations have "low risk of adverse cognitive effects." 
• In 1994 Simon Lewis was in his car when it was struck by a van driving at 75 miles per hour. The crash killed Lewis' wife, and “destroyed a third of his right hemisphere” according to this press account. Lewis remained in coma for 31 days, and then awoke. Now, many years later, according to the press account, “he actually has an IQ as high as the one he had before the crash.” In 1997, according to the press account, Lewis had an IQ of 151, which is 50% higher than the average IQ of 100. How could someone be so smart with such heavy brain damage, if our brains are really the source of our minds?  
• In a scientific paper "Why Would You Remove Half a Brain? The Outcome of 58 Children After Hemispherectomy −−The Johns Hopkins Experience: 1968 to 1996" by Vining and others, we read about how surgeons at Johns Hopkins Medical School performed fifty-eight hemispherectomy operations on children over a thirty-year period. Eleven of these children had the left hemisphere of their brains removed; most of the rest had the right hemisphere of their brains removed.  The paper states this: "Despite removal of one hemisphere  [i.e. one half of the brain], the intellect of all but one of the children seems either unchanged or improved. " We are told "language recovers after removal of the dysfunctional left hemisphere," and the authors speculate about why it is they saw "intellectual improvement in these children after removal of half of the cortex." The authors state, "We are awed by the apparent retention of memory after removal of half of the brain, either half, and by the retention of the child’s personality and sense of humor." The final statement is very important. Although the authors do not give us the results of exact tests documenting a preservation of memory, the statement I just quoted suggests they observed a preservation of episodic and factual/conceptual memory after half of the brain was removed. 
• The paper "Cognitive Impairment 3 Months After Moderate and Severe Traumatic Brain Injury: A Prospective Follow-Up Study" gives us the result of cognitive tests on people who had brain injuries as the result of events such as falls and traffic accidents.  We have some tables that are hard to read. In the Discussion section we read that after moderate Traumatic Brain Injury (TBI), "most patients had a normal neuropsychological assessment," with no more than 1 score much below normal (or, to put it more technically, no more than 1 score below 1.5 standard deviates below the norm).  We read that "even after severe [brain] injury, normal performances were found in one third of patients." The authors say, "This was unexpected." We are told that the average total IQ score of 35 subjects with moderate traumatic brain injury was an above-average score of 109, and the average total IQ score of 26 subjects with severe traumatic brain injury was an above-average score of 103. There is a reason to suspect that some subjects may deliberately perform poorly in such tests. Some of the subjects (such as those injured in a crash) may have pending law suits, and may think that good performance in cognitive tests may reduce their chance of being rewarded lots of money in a law suit. 
• At the page here, we read an account of a girl who had the left half of the brain removed in a hemispherectomy operation, to try to stop severe seizures. We hear of a successful operation. We are told, "In addition to the seizures, Rehab also struggled with being able to remember things before her surgery." In the next sentence we hear one of the girl's parents saying, "Her memory was so poor, but now she remembers everything."  This is the opposite of what you would expect under the "brains make minds" hypothesis. 
• The paper "Neuropsychological functioning during the year following severe traumatic brain injury" studied cognitive functioning in 65 subjects who had severe brain damage, mostly after road traffic crashes. The patients were rated with a level of impairment of "mild" or "severe" on various measures, based on tests 6 months after the injury and 1 year after. Fewer than half of the subjects were rated as having "severe" impairment in memory performance tests taken at the 1-year mark. Only 9% of the subjects were rated as having "severe" impairment in one test of executive function at the 1-year mark, with a minority rated as having "severe" impairment in another test executive function at the 1-year mark. One test of attention at the 1-year mark result showed only 8% with a severe impairment, and another test of attention at the 1-year mark result showed only 28% with a severe impairment. There is a reason to suspect that some subjects may deliberately perform poorly in such tests. Some of the subjects (such as those injured in a traffic accident) may have pending law suits, and may think that good performance in cognitive tests may reduce their chance of being rewarded lots of money in a law suit. Moreover, we must also wonder whether the scientists selecting the subjects had a bias in looking for subjects with particularly bad memory problems. The average IQ of the brain-damaged subjects was 93, and we don't know whether this below-average result was caused by brain injury.  There is reason to suspect that the set of average people suffering from traffic accident brain damage may be slightly below average in IQ, given that higher IQ might tend to avoid such accidents. 
• The paper "Association of Traumatic Brain Injury With Dementia and Memory Decline in Older Adults in the United States" used a very large sample of 9,794 patients who had an assessment of traumatic brain injury.  The study says, "There was no significant relation between history of TBI [traumatic brain injury] with LOC [loss of consciousness] and memory score or memory decline." We read this: "In a nationally representative prospective cohort of older adults free of dementia at baseline, we did not find evidence for any long-term associations between history of TBI [traumatic brain injury] with LOC [loss of consciousness]  (of unknown frequency and severity) and risk of dementia over 14 years of follow-up. " We read that "similarly, decline in memory performance did not differ between participants with or without history of TBI with LOC." The authors state, "our findings showing no association between TBI history with LOC and dementia are consistent with the results of several other recent studies looking at dementia, AD [Alzheimer's Disease], or AD biomarkers or neuropathology." 
• The paper "Working Memory after Traumatic Brain
  Injury in Children" tested working memory in eighty children with mild or severe traumatic brain injury (TBI). The paper has nice easy-to-read graphs comparing the performance of the brain-injured with controls, and the first two of the graphs show no appreciable difference in performance in two working memory tests, even when comparing the severe cases with control (uninjured cases).  
• The paper "Central executive system impairment in traumatic brain injury" is one that does not give us a random sample of patients with traumatic brain injury, because the paper tells us this about its 64 patients: "Patients were selected for participating in the study if they complained of lack of attention, poor
  memory or loss of efficiency in everyday life." Despite such a selection bias, Table III of the paper tells us that the majority of the subjects had "normal performance" in long-term memory acquisition, long-term memory storage, long-term memory delayed recall, sustained attention and short-term memory, with an average of about 60% of the subjects being normal in such areas.  
• At the University of Chicago page here, we read, "Nordli recalled a patient whose IQ rose to 100, a normal intellect, from 80 before hemispherectomy." The patient seemed to get much smarter after they took out half of the brain. 
• The very interesting paper "Preserved Cognition After Right Hemispherectomy" gives us extensive performance tests for a woman who had almost all of her right brain removed after a severe stroke at age 29. We have a very good visual showing that her performance on a wide variety of cognitive tests is average or slightly below average. 

A 2020 paper gives us an indication of the appalling failure of neuroscientists and doctors to properly test for losses of pre-surgical episodic memories and pre-surgical learning in people who had hemispherectomy operations. We read this:

"Only four studies have investigated memory functioning prior to and following hemispherectomy surgery. It is worth noting that all used short-term memory tasks, typically involving immediate repetition or recognition and did not test for more challenging aspects of memory involving recall or recognition over longer delays."

The authors of a 2017 paper tell us something similar. Referring to hemispherectomy operations in which half of the brain is removed, it says this:

" Physicians have long wondered about the surprising finding that one can lead a normal life with only one hemisphere....

The discrepancy between cerebral and cognitive functioning in these cases is strikingly highlighted by the fact that most patients, even adults, do not seem to lose their long-term memory such as episodic (autobiographic) memories. Even so, this puzzle, and possible explanatory models for this retention of long-term memory, is only rarely

discussed in the medical literature dealing with hemispherectomy. Although memory features are sometimes assessed by using the Wechsler Memory Scale (e.g., Loddenkemper et al., 2004), we were unable to find a single peer-reviewed publication in which the peculiar retention of the patient's autobiographic memory was explicitly addressed. That said, this remarkable phenomenon was at least casually mentioned by authors such as Dandy (1933) and Bell and Karnosh (1949), who stated that their patient's memory seemed unimpaired after hemispherectomy. Similarly, Vining et al. (1997) were surprised by the apparent retention of memory after the removal of the left or the right hemisphere of their patients. Dorman (1991) described the extraordinary case of a subject who was able to perform brilliant calendar calculations, although his left hemisphere had been removed several years before."

Despite this appalling failure to properly test whether episodic memories and learned information are preserved after removing half of a brain, several of the studies quoted above make statements strongly suggesting that such memories are preserved after removal of half a brain, contrary to the dogma that memories are stored in brains. And when studies such as the ones above tell us that there are usually no major cognitive effects of removing half of a brain, we can regard this as being a rather clear indication that episodic memories and learned information are well-preserved after removal of half of a brain, as any major loss of such  episodic memories and learned information would be a severe cognitive effect that should be reported. 

The quote above refers to Dandy. Here is the basis of the reference. The case of Dandy's patients are reported in the American Journal of Psychology, Vol. 46, No. 3 (Jul., 1934), pages 500-503. We read this: 

"Dandy has completely removed the right cerebral hemisphere from eight patients. He has performed total extirpations of one or more lobes much oftener... There are tabulated below certain generalizations on the effects of removing the right hemisphere.... The operation was the complete extirpation of the right frontal, temporal, parietal, and occipital lobes peripheral to the corpus striatum. The weight of the tissue removed varies, with the pathological conditions involved, from 250 to 584 grm [grams].Coherent conversation began within twenty-four hours after operation, and in one case on the afternoon of the same day. Later examinations showed no observable mental changes. The patients were perfectly oriented in respect of time, place, and person; their memory was unimpaired for immediate and remote events; conversation was always coherent; ability to read, write, compute, and learn new material was unaltered. Current events were followed with normal interest. There were no personality changes apparent; the patients were emotionally stable, without fears, delusions, hallucinations, expansive ideas or obsessions, and with a good sense of humor; they joked frequently. They showed a natural interest in their condition and future. They cooperated intelligently at all times throughout post-operative care and subsequent testing of function." How could the memory of patients be "unimpaired for immediate and remote events" if memories are stored in brains?

The quote above also refers to the Vining paper I quote from above. The quote also refers to Bell and Karnosh, who in 1949 referred to 4 operations they had done, stating, "In all cases the relative freedom from severe physical handicap and gross mental defect after removal of almost half the cerebrum was striking" (pages 285-286). That is not a quote anyone would make if patients had lost their episodic or learned memories. 

All in all, the results discussed above are consistent with the idea that the human brain is not the storage place of human memories and is not the source of the human mind.  The results are not the results we would get if brains stored human memories and brains produced minds.