Does Memory Reside Inside The Brain
June 21, 2010 by selfimprove
On Jun 2, 2005, NBC Philadelphia had an interesting report. Christina Santhouse had caught a virus that caused a rare brain disorder known as Rasmussen’s Syndrome at an age of 8. And her doctor had to perform hemispherectomy, removal of half of the brain, on her. After 10 years, Christina was about to graduate from high school with honors. After the surgery, she had a slight limp and her left hand didn’t work at all. She had also lost her peripheral vision, but otherwise, she was an ordinary teen. A similar case was reported on Telegraph (UK) on May 29, 2002, a girl named Bursa had the same disorder and her left brain was removed when she was 3, she became fluent in Dutch and Turkish when she was 7. In 1987, A. Smith reported that one patient with hemispherectomy had completed college, attended graduate school and scored above average on intelligence tests. Studies have found no significant long-term effects on memory, personality, or humor after the procedure, and minimal changes in cognitive function overall.
The outcome of hemispherectomy is surprising. Neuroscience tends to suggest memory is stored in the neurons in the brain. If that premise stands true, removing half of the brain would destroy one’s memory if memory is stored in the network structure of neurons as one school of cognitive physiology suggests, or at least destroy half of the memory if bits of memory information are stored in individual neurons in the brain as suggested by another school of cognitive neuroscience. But it is apparent that the results disagree with either of the explanations. Removing part of the brain has been one of the standard surgical operations for severe epilepsy and has been performed thousands of times. Many of the results are quite similar to those of hemispherectomy.
The orthodox explanation for the observation is that information stored in the infected brain areas is duplicated in the health part of the brain prior to the surgery. This rationalization is still inadequate when you take into account how a brain surgery is performed. Surgeon has to remove the infected area and some surrounding health tissue, sometimes a much larger tissue than the infected area, to make sure infection does not spread. If the information stored in the infected areas is reproduced somewhere in the brain before surgical procedure, some information is still lost when surrounding health brain tissue is removed, consequently the memory would suffer.
This is not observed after the surgery. So it is necessary to assume that the memory stored in the neighboring health tissue is also replicated in other parts of the brain. This raises a question: how does the brain know how much health tissue is going to be taken out? If the brain does not know, surgeries will inevitable destruct part of the memory. The belief that memory is stored in the brain (in neurons or in the network of neurons) apparently contradicts with findings in brain surgeries.
In the 1920s Karl Lashley conducted a series of experiments trying to identify which part of the brain memories are stored. He trained rats to find their way through a maze, and then made lesions in different parts of the cerebral cortex in an attempt to erase its original memory trace. His experimental animals were still able to find their way through the maze no matter where he put lesions on their brains. He therefore concluded that memories are not stored in any single area of the brain, but are instead distributed throughout it. Distributing the memory of every single event over the whole brain is energetically inefficient and mathematically impossible. If his reasoning is not confined to the brain, the logical conclusion should be that memory is not stored in the brain.
Instincts are obviously inherited and nobody has any slight idea where the information making up the instincts is stored, and cognitive memory is thought to be acquired through experience and stored by changing the signal chemicals in the neurons in the brain.
New research reveals that even cognitive memory can be inherited. A study by Larry Feig at Tufts University School of Medicine in Boston indicates that mother mice that receive mental training before they become pregnant can pass on their cognitive benefits to their young even there is no direct contact among the mothers and their offspring. It is obvious that the cognitive memory is not acquired by the young through experience, and there is no apparent way for the young to store the information in their neurons, then where do the young retrieve the memory from? Maybe from where they store their instincts information, a place nobody knows yet.
“Brain areas such as the hippocampus, the amygdala, the striatum, or the mammillary bodies are thought to be involved in specific types of memory. For example, the hippocampus is believed to be involved in spatial learning and declarative learning, while the amygdala is thought to be involved in emotional memory. Damage to certain areas in patients and animal models and subsequent memory deficits is a primary source of information. However, rather than implicating a specific area, it could be that damage to a pathway traveling through the area is actually responsible for the observed deficit” (excerpt from http://www.wikipedia.com). If one stores all his possessions in a warehouse connected to his house through a highway, he would not be able to get anything from the warehouse if the highway is broken down. To infer that everything is stored on the highway based on the facts he can not get anything when the highway is interrupted is ridiculous. Even the connection between the brain and memory is well established, it is beyond logic to conclude that memory reside inside the brain.
Wilder Penfield was a pioneer in associating particular type of memory with specific area in the brain. When he was conducting surgeries to remove specific types of temporal lobe loci which were causing epilepsy, he made ground-breaking discoveries by taking notice that his un-anesthetized patients (with local pain blockers) could listen and respond to his questions while their temporal lobe was being operated upon. Indeed, the verbal feedback by the patient was an essential requirement so that Penfield could determine that he was excising exact portion of the brain which was the cause of the neurological symptoms being treated. He would insert an electrode into patient’s brain and provide electrical stimulation to see how the patient responds.
One of Penfield’s patients heard a specific music selection being performed by an orchestra “when a point on the superior surface of the right temporal lobe was stimulated after removal of the anterior half of the lobe.” The sound was so clear that the patient believed that there was a phonograph in the operating room. As the same point was re-stimulated (without withdrawing the electrode, only stop and re-supply electrical stimulus) the music began at the same spot in time where it had previously begun.
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