They Lost Huge Parts of Their Brains, But Their Knowledge and Recollection Were Preserved

 When people think of neuroscience experiments, they typically think of experiments done with mice. If they think of neuroscience experiments involving humans, they may think of some experiment involving the use of some drug, with a test to see whether the drug affects mental performance.  Such experiments are formally designed with things such as a set of test subjects, a set of control subjects that do not have any intervention occurring to them, and so forth. 

But some of the most important experiments in neuroscience have been those that were not part of some procedure declared as an experiment. The experiments have occurred when some large part of a human brain was removed in surgery. Whenever such an operation is done, it is an important experiment that tests the credibility of the claims that neuroscientists so often make. 

Neuroscientists are always claiming that learning occurs through some brain action, that memories are stored in brains, and that recall of a memory occurs by some action of the brain. Neuroscientists senselessly keep making such claims despite their lack of any credible theory describing how any such things could be done by a brain. When a neuroscientist is asked to explain how a brain could store some newly learned knowledge, a scientist will typically engage in some vague, vacuous hand-waving which typically consists of merely reciting some little slogan or sound bite such as "synapse strengthening." There is nothing to speak of behind such a phrase, which is a mere vacuous catchphrase. When asked to explain how a human can instantly recall some knowledge, a neuroscientist will typically say nothing but the most vacuous phrase such as "stored information is recalled." 

Although not called "experiments," every time a large part of the brain is removed from a human, a very important experiment is being performed, one that sheds light on whether neuroscientist claims about memory are credible.  Under the theory that memories are stored in brains and retrieved by brains, we should expect to observe certain things:

(1) We should expect that there should be some deterioration in the ability of humans to learn new information. Such a deterioration might be small or large, depending on where brain tissue was extracted, and how brain tissue was extracted. 

(2) We should expect that there should be some loss of learned knowledge and episodic memories. Such a deterioration might be small or large, depending on where brain tissue was extracted, and how much brain tissue was extracted. 

Item (2) is often overlooked, but is obviously something to be expected under the theory that brains store memories. Imagine if someone writes down what happened to him each day, in a large book that originally consisted of blank pages. Obviously if you were rip out a large chunk of these pages and burn them, that would cause a large loss of the information that had been recorded.  It is just as obvious that if memories are stored in brains, then surgically removing some large chunk of the brain should cause some large loss of what a person had learned or the memories the person had. 

If memories are stored in the brain we should expect that a surgical removal of a large amount of brain tissue might produce effects such as these:

(1) A loss of the ability to understand some words in a person's language. Each recognition of a word that occurs when a person hears something involves the use of some learned knowledge that a person acquired sometime in his life.  

(2)  A loss of the ability to speak or write some words in a person's language. Each use of a word that occurs when a person speaks something or writes something involves the use of some learned knowledge that a person acquired sometime in his life.  

(3) A loss of the ability to recognize various types of images such as particular faces or particular words or particular symbols. Every time a person recognizes a word or a face or an object or a symbol, that involves the use of some  learned knowledge that a person acquired sometime in his life.  

(4) A loss of the ability to recall various concepts and facts that the person had learned at some time in his life. For example, a person might no longer remember what country or city he lived in, or what his name was, or what his address was. Or a person might no longer be able to explain who some famous historical figure was, someone such as Jesus or Napoleon. 

(5) A loss of episodic memories. For example, a person might no longer be able to tell you the story of his life, or tell you what type of activities he engaged in last year. 

To test whether memories are stored in brains, we can track down case histories of people who had large amounts of brain tissue surgically removed, and examine which, if any, of the effects above occurred.  Let's look at some examples of such cases. 

First, let's look at the case of Beth Usher of Storrs, Connecticut (part of the USA). Beth was mentioned in an article in the LA Times, which says she was one a group of epileptic children who had half of their brain removed, to stop very bad seizures that drugs could not stop. The article stated this:

 "How is it that 8-year-old Beth Usher of Storrs, Conn., can lose her left hemisphere, yet retain her large repertoire of knock-knock jokes? Beth’s memories survived not just the loss of brain tissue, but also the 32 days that she spent in a coma, the result of some brain stem swelling that occurred in response to the trauma of surgery. Shortly after Beth regained consciousness, her father began quizzing her about people and places from her past. Brian Usher didn’t get very far. 'Dad,' Beth interrupted, with a trace of impatience. 'I remember everything.'" 

We have here the explicit claim that Beth's memories survived the removal of the left half of her brain.  The article mentions specific things that Beth could still remember, and makes no mention of any memory or knowledge that was lost after half of her brain was removed. 

Another case is discussed here, in a book chapter of a textbook. We read of a patient E.C. who had a large brain tumor. To treat the tumor, the left half of the patient's brain was removed, in a hemispherectomy operation. We read that "the entire hemisphere was removed in one piece" on December 7, 1965. We read that "immediately following hemispherectomy" the patient had an "ability to follow simple verbal commands."  We read on page 107 that "the patient spontaneously articulated words and short phrases fairly well immediately after the operation."  

The discussion of the patient's retention of previous knowledge is rather frustrating in its lack of a comprehensive treatment. We read that this patient E.C. "gave the correct number of years when asked how long he had lived at his house." We read on page 107 that on January 26, 1966 (about six weeks after the operation) he "slowly but correctly selected four of the first six items from six pages, each with four items to choose from, before indicating he was tired" when given the Peabody picture vocabulary test. Such a test involves a tester speaking a word, and the user pointing to the correct picture in a grid of 4 pictures. 

The image below (from the paper here) shows an example of one of the pages. The word spoken by the tester is "citrus."

The result described above (4 out of 6 correct on six such pages) clearly suggests that patient E.C. retained his learned knowledge after the left half of the brain was removed. Since the test was given only six weeks after the operation, and E.C. was in a recovering state during those weeks in which he was not being schooled, we cannot explain such a result as being due to knowledge acquired during those six weeks. We also read on page 107 that on June 3, 1966 patient E.C. correctly named 85 out of 112 items on such a test. No mention is made of schooling occurring during the first six months of 1966. 

According to the paper here, "In the fifth postoperative month, E.C. showed sudden recall of whole old familiar songs (e.g., My

Country 'Tis of Thee, Home on the Range, church hymns)."

On page 109 we read of three other cases of the removal of the left half of the brain, and we read that "speech and verbal comprehension were present immediately after left hemispherectomy in all three cases." We read nothing about any loss of knowledge or episodic memories in any of these cases. 

In the scientific paper here, we have on page 248 and page 250 before and after test scores for various subjects who had of their brains removed in hemispherectomy operations.  The IQ score differences are slight. IQ tests don't involve learned information, but almost any IQ test would be largely a test of memory, as it would be a largely a test of ability to read test questions.  

On the same pages we have before and after test scores for Peabody Picture Vocabulary Tests given to various subjects who had  half of their brains removed in hemispherectomy operations.   In these tests, someone is shown picture cards like the one below. The tester speaks a word corresponding to one of the pictures, and the subject tested is asked to point to the correct picture matching that word.  These tests are tests of memory retention after removal of half of the brain.  On these memory tests there was no decline in the score of 21 subjects mentioned on page 248, and no decline in 7 subjects mentioned on page 250. 

The 2021 paper "Preserved Cognition After Right Hemispherectomy"  by Mark Bowren, Jr,  Daniel Tranel and Aaron D. Boes tells us the fairly recent case of a woman who had almost the entire right half of her brain removed, but is apparently suffering very little cognitive damage from this removal. We read that the woman had a brain stroke at age 29, and that doctors treated her brain problem by removing almost all of the right half of her brain, in an operation called a hemispherectomy. We read that "In the days after surgery, she was described as alert, cooperative, and having normal language and interactions with her providers." We read no mention in the paper of a loss of acquired memories.  

The phrase "having normal language" is a very important indication that learned knowledge was preserved after almost all of the right half of the brain was removed.  Every time a person uses language in speech, that involves a use of acquired memories. Every single use of a particular word requires a memory of the definition of that word.  

Also we read that two months after the stroke, this patient CB had "intact expressive language and reading comprehension."  The paper does not tell us how many weeks after the stroke there occurred the removal of almost all the right half of the brain. But from the timeline given we know that this sentence refers to some time less than two months after the operation occurred.  Because you cannot learn a large fraction of a language in less than two months, we can presume that the patient had "intact expressive language and reading comprehension" directly after having had almost all of the right half of her brain removed, particularly given that we are told that the patient had "normal language" days after the operation. 

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") 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....Although there have been major concerns about loss of language after left hemispherectomy, all eleven of these children have regained virtually normal language....It is tempting to speculate, that the continuous electrical activity of these severely dysfunctional hemispheres interferes with the function of the other, more normal hemisphere. This might explain why motor function improves after hemispherectomy and why language recovers after removal of the dysfunctional left hemisphere, but does not seem to fully transfer before surgery. Perhaps it also partially explains intellectual improvement in these children after removal of half of the cortex. 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."

There is a reason why we can be confident that removal of half of a brain in hemispherectomy operations does not cause any major loss of learned memories.  If there was a case of any such thing happening, you can believe that it would be endlessly recited by those who wish for us to believe that memories are stored in brains. But there is no such case that is cited. 

The visual below "speaks volumes" on this topic. It is the result of a search on Google Scholar for "amnesia after hemispherectomy." "Hemispherectomy" is the standard name for the operation that has been performed thousands of times, in which half of the brain is removed to stop very bad seizures. "Amnesia" is the main term used for a loss of episodic memories.  Any search on Google Scholar will produce very many results when there are cases corresponding to such a search. For example, doing a Google Scholar search for "vision loss after automobile accident" produces many results. But doing a search for "amnesia after hemispherectomy" produces zero results.

Entitled "Man With Half a Brain," the 1912 newspaper article below (which you can read here) tells us of a soldier who was shot in the head. First, we are told that he lost his memory, but then the article says that "gradually his memory has returned, and he recollected what happened in his childhood." Then the article tells us this: "And now he remembers everything up until the third day before he was shot." 

The news story here documents a very clear case of the preservation of memory after the removal of the left half of the cerebrum. We read of a 47-year-old man who had the left half of his cerebrum removed. We read this:

"Dr. Smith said the patient's memory of events before the operation 'was well preserved, much better than anyone expected.' Tests following surgery show Coe can perform many functions traditionally thought impossible after removal of the brain's dominant hemisphere. Immediately following surgery, Coe still had the ability to speak spontaneously."

A report like this does not merely contradict the claim that the brain is the source of the mind. It also contradicts the claim that the brain is a storage place of memories. 

The results discussed in this post deserve to be pondered at great length. The results indicate very strongly that the human brain is not any storage place of human memories. After considering such results, you should also ponder the most important null result of neuroscience research: the fact that brain tissue from thousands of living and recently deceased humans has been microscopically studied at great length, with the most powerful microscopes; but no one has ever found the slightest trace of learned information or any episodic memory by such microscopic examination. No one found a single phrase, a single word or even a single letter of the alphabet after microscopically examining brain tissue. Nor did anyone ever find by microscopic examination of brain tissue any trace of anything a human ever saw or heard.