Difference between brain hemispheres


#1

The human brain is split with two hemispheres with different cognitive natures (i.e. left vs right brain thinking). So this brings the question as to the difference between the individual cortical columns in the left vs the right brain. Are there differences? If not, what is causing the hemispheres to be thinking differently?


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#2

Before you get too hung up on that I encourage you to read about patients that have had a hemispherectomy or the spit-brain cases.

This has been an area of intense research. Yes there is specialization. Yes, this specialion has much more to do with functional connectivity as any intrinsic property of the processing fabric itself.

Much of the popular literature on left/right brain functions have been of very low value.


#3

So as I understand what you said: (1) There indeed is specialization between the two hemispheres and (2) The specific specialization would differ from person to person? I do know the split brain patients have different behavior response depending on what hemisphere is doing the thinking.

What the do you mean of ‘very low value’? Are there cases where the two hemisphere behave in the same way?


#4

When I say popular press and low value I am speaking to the “woo woo - left brain/right brain” thinking.
There is clear lateralization of speech and spatial processing. The two areas are strongly bonded together with the corpus callosum to the point where they act as adjacent maps.

As far as “acting the same way” in split-brain patients they clearly behave differently. You seem to have two functioning brains with different capabilities

What is more subtle and very interesting - in hemispherectomy the patient regains full function with only half a cortex.
“Overall, hemispherectomy is a successful procedure. A 1996 study of 52 individuals who underwent the surgery found that 96% of patients experienced reduced or completely ceased occurrence of seizures post-surgery. Studies have found no significant long-term effects on memory, personality, or humor, and minimal changes in cognitive function overall. For example, one case followed a patient who had completed college, attended graduate school and scored above average on intelligence tests after undergoing this procedure at age 5. This patient eventually developed “superior language and intellectual abilities” despite the removal of the left hemisphere, which contains the classical language zones.”


#5

I think the age at which this procedure occurred made a crucial difference. There are so many things a 5-yr-old brain has not learned yet, the procedure was not nearly as disruptive as it would have been to an adult.


#6

I was speaking to the point:

“So this brings the question as to the difference between the individual cortical columns in the left vs the right brain. Are there differences? If not, what is causing the hemispheres to be thinking differently?”

Left or right can perform the functions, it is up to connectivity. I don’t think that there is anything special in the local construction that forces a section of cortex to be spatial or a speech center.


#7

Next time, be careful when you say “low value”. The left and right hemisphere’s do develop to function differently (why?). There is however value in having what appears to be different cognitive value. I bring this up because the paper discusses both a sequential mode of cognition and another mode that recognizes composition. The question then is, is this whole hemisphere or is each cortical column doing both? I can argue that it is NOT the latter because it doesn’t take into account left-right hemisphere distinction.

So perhaps the capability is available in all columns in the brain, but through development, one hemisphere favors one kind over the other.

Is there experimental evidence that shows recently severed brain that exhibit different competencies in the task described in the paper?


#8

Are you referring to what / where pathways? If so I’ve seen no evidence suggesting these pathways have anything to do with hemispheres.


#9

I’m sorry I was not clear on this. When I say popular press I am speaking of the cheap self-help magazines you see at the supermarket checkout lanes - not scientific journals. I see articles in these magazines where some “guru” talks about if a person is “left or right brain” and how that means they have some special artistic ability or some other special gift. The advise that follows is often no better than the note in your fortune cookie.

All “normal” humans use all of their brains and the parts work together to form a complete function set. There are approximately 100 processing maps distributed in the normal human brain. All humans have an inventory of mental skills that vary by the innate map relative sizes, map connectivity, and training or experience. Some of these functional maps such as speech processing and spatial processing are lateralized. This is a much more nuanced issue than some “left /right brain” generalization.

In vision and hearing the left/right processing is mixed together is the same map to do useful functions like stereo vision extraction or sound localization by phase delays between auditory sensors.