Saturday, April 23, 2016

Locating Abstractions in the Brain

The most human part of the brain is also the murkiest and least understood. Visualization studies of what is going on in the frontal cortex.

While it was in vogue, the lobotomy operation was used to treat in the neighborhood of 100,000 people in the mid twentieth century, rendering them more manageable- something that has since been more easily achieved with drugs. From the Wiki page:
"The purpose of the operation was to reduce the symptoms of mental disorder, and it was recognized that this was accomplished at the expense of a person's personality and intellect. British psychiatrist Maurice Partridge, who conducted a follow-up study of 300 patients, said that the treatment achieved its effects by 'reducing the complexity of psychic life'. Following the operation, spontaneity, responsiveness, self-awareness and self-control were reduced. Activity was replaced by inertia, and people were left emotionally blunted and restricted in their intellectual range."

What is odd is that for such a massive disruption to the brain, the effects were diffuse and hard to understand (though in fairness, the methods used were hardly uniform). "The first bilateral lobectomy of a human subject was performed by the American neurosurgeon Walter Dandy in 1930. The neurologist Richard Brickner reported on this case in 1932, relating that the recipient, known as 'Patient A', while experiencing a flattening of affect, had suffered no apparent decrease in intellectual function and seemed, at least to the casual observer, perfectly normal."

Some effects were that the subject no longer dreamed, they also lost their theory of mind, or the ability to empathize with others. Some entered a stupor or started suffering siezures. There were various intellectual and personality deficits- one became "smiling, lazy and satisfactory patient with the personality of an oyster". Five percent died. One subject mentioned:
"It took a great deal of effort to keep an abstraction in mind. For example, in talking with the speech therapist I would begin to give a definition of an abstract concern, but as I held it in mind it would sort of fade, and chances were that I'd end up giving a simplified version rather than one at the original level of conception. It was as though giving an abstraction required so much of my addled intelligence that halfway through the definition I would run out of the energy available to me and regress to a more concrete answer. Something like this happened again and again."

An irony is that the Soviet Union took the lead in banning the procedure, "Doctors in the Soviet Union concluded that the procedure was 'contrary to the principles of humanity' and 'through lobotomy an insane person is changed into an idiot.'"

Modern brain scanning allows researchers to peer into the frontal lobes and start figuring out what is going on there. A recent paper described some early work in that direction, devising simple tasks to differentiate levels of abstract thought and mapping where they happen, using fMRI. They manage to map separate zones in the frontal cortex that handle temporal / time shifting abstractions, category switching abstractions, and feature attention control.

The subjects were presented with points that through several frames that added up to a diagram, (C), a star with letters on the outside, with a color applied. There were several rules imposed, such as if the color setting was purple, the letters were supposed to be added up to form a word across the star (TABLET, in this case). If the color was orange, the subject was supposed to just trace the points of the star with her eyes. Then delay rules were added, asking whether the trail was the same type or a different type than the one before. Or the subject was given a new diagram but asked to maintain their place in the old diagram, to be recalled later. Then distraction periods were added in between to test for memory retention. It all begins to look like an intelligence test, for the subject's ability to keep ideas and rules in mind successfully.

Test design, in part. C shows the basic image presented to the subject, which would have included color as well, and varied the shape and text presented. The points of the star were not presented at once, but fed out one point at a time. B shows the combined tests that were devised. For instance. The restart test asked the subject not to delay their analysis, but just presented with a new diagram and asked to resolve the color and text diagram by the agreed rules.

The tests were designed to separate three topics of thought, and were added together in various combinations to allow the researchers to run combinatorial tests. The upshot was that they were able to map the three tasks to different parts of the frontal cortex:

Distinct mappings of each task to its region. Handling time delay and abstraction occupies the very front of the brain, (rostral), while simpler abstractions keeping track of the local context of a task, or attending to selected features of an image/task occupy precincts farther back (caudal). This is in addition to separate zones in the mid-brain
"Regressing these measures onto activation revealed a clear gradient such that caudal LPFC [lateral prefrontal cortex] was related to current, but not future processing, while rostral LPFC was related to future, but not current processing, with mid LPFC showing activity related to both current and future processing "

They end up with a beautiful depiction of the regions of the brain where their various tasks took place. Unfortunately, fMRI imaging technology remains very crude, in time and space, so their task breakdown was similarly crude to suit. It will probably take new technology to go to deeper detail on what is going on in the human frontal cortex- the part of the brain most responsible for making us human, but also, since it handles abstractions farthest from detailed concrete processing, the most nebulous and hard to define.

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