The 2021 paper "Preserved Cognition After Right Hemispherectomy" is another example of a case that should have been "the talk of the town" in the world of science, but which instead seems to have received almost no attention from the press. The paper 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 failure of scientists and doctors to study the exact memory effect of removing half of the brain is a major scandal of neuroscience. Whenever a person has a large portion of the brain removed, you have a great opportunity to test the hypothesis that memories are stored in the brain. This is because if it is true that human memories are stored in the brain, you should see some great loss of memories whenever a large chunk of the brain is removed. But senselessly, neuroscientists and medical authorities seem to fail to test a loss of acquired memories after removal of large portions of the brain.
Doing such a test would be quite easy. For example, a person could be given a test of the definition of 200 common words and could be given a multiple-choice test involving 200 commonly known facts; and such tests could be given both before and after the removal of the large amount of brain tissue. A sharp decrease in the score on such tests would indicate that the person had lost much of the school-learned knowledge that he previously had. Also, a person could be asked to write a 1000-word autobiographical essay, both before and after the removal of the large amount of brain tissue. From the facts in such an essay written before the surgery, you could make a set of 25 or 35 questions and answers. This set of questions and answers could be asked both before the surgery and after the surgery. If it was found, for example, that the person given the brain surgery could no longer answer 10 of the autobiographical questions that the person could answer before the surgery, this would be an indication that the brain surgery had caused the person to lose some of his episodic memories.
Senselessly, doctors and neuroscientists fail to do tests like this before and after removing large portions of the brain. Or, if they do such tests, they fail to publish them. So we are left having to deduce how much of an effect the brain removal had on acquired memories, using other clues, and using the failure to report a loss of acquired memories and episodic memories as evidence that no great loss of such things occurred. In the case of this woman, we can do that. The paper has failed to mention any loss of conceptual knowledge and has failed to mention any loss of episodic memories. From this we may infer that there was no such loss.
Also, the paper has stated this about the aftermath of the dramatic surgery in almost all of the right half of the brain was removed: " In the days after surgery, she was described as alert, cooperative, and having normal language and interactions with her providers." 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.
While the authorities involved failed to properly test for a loss of acquired knowledge and episodic memories, they did do a good job of testing the patient's cognitive skills at a time 5.3 and 7.8 years after the operation. They have given us the visual below, which neatly summarizes in a single visual the loss of brain tissue that occurred and the results of the cognitive tests:
As you can see from the visual above, the patient scored in the "Average" range for almost all of the 29 tests. In only two of the dozens of tests did the patient get an "Impaired" score: a test involving symbol search and a test involving copying figures. We read this:
"Neuropsychological test performances (data collected 5.3 and 7.8 years after the onset of the stroke; figure)4 were notable for normal performance on most tests, including on most nonverbal tests, such as the Block Design test, the Matrix Reasoning test, the Visual Puzzles test, the Judgment of Line Orientation test, the Benton Visual Retention test, the Spatial Span test, and the Faces I and II tests. In addition, she performed within normal limits on several tests of executive functioning, including the Wisconsin Card Sorting test, part B of the Trail Making test, the Color-Word Interference test, and the Similarities test (a test of abstract verbal reasoning and comprehension of implied meanings). Regarding attention, she performed within normal limits on the Line Cancellation test, a test of hemispatial inattention (neglect), and there was no evidence of hemispatial inattention on other neuropsychological tests. Focused and complex attention were within normal limits on parts A and B of the Trail Making Test, respectively."
So how does this data fit in with the claim that your brain makes your mind? It doesn't. The data defies such a claim. The case also defies claims that the brain is the storage place of memories. The paper has failed to mention any loss of acquired knowledge or episodic memories from the removal of half a brain, and has given us some indications that no big loss of that type occurred.
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