Lateralization of Brain Hemispheres

Discussion of the bicameral mind, Jaynes's neurological model, the dual brain concept and neuroscience research, present and historical.
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faustolevantesi
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Lateralization of Brain Hemispheres

Post by faustolevantesi » Sat Jul 06, 2013 4:19 am

Hi everybody,

As far as I have understood, Jaynes' hypothesis for the evolution of consciousness is that the two brain hemispheres were once able to communicate almost all the time, whereas today they only communicate in very rare cases.

Does it mean that consciousness results just from the lack of communication between the two hemispheres?

And does Jaynes' hypothesis imply that brain lateralization has been increasing or diminishing in extent in the emergence of consciousness?

Thank you.

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Re: Lateralization of Brain Hemispheres

Post by Moderator » Mon Jul 22, 2013 4:05 pm

While you are in the ballpark, this is not what Jaynes was saying.

There is no reason to believe that there was not regular inter-hemispheric communication in both the conscious and bicameral minds (as well as much earlier). The differences were that during the bicameral period, language had not developed to the level of complexity to allow for an internal mind-space (introspection). The brain used language to communicate experience from the right hemisphere to the left. As consciousness was learned, the hallucinatory function of the right hemisphere language areas became suppressed (brain scans reveal a lack of right hemisphere suppression in cases of people who hear voices today).

Jaynes did not propose a neurological model for consciousness, and I would not think of consciousness strictly in terms of inter-hemispheric communication (although this may be a factor). For example, children who have a hemisphere removed at a very young age still display most if not all of the features of consciousness (there is another thread in this forum on that topic).

Technology has now progressed to the point that neurological models of consciousness are being proposed. You can see some of these studies on Google scholar and elsewhere. For one example, see "Self awareness and speech processing: An fMRI study" by Renaud Jardri, but there are many others.

For a thorough understanding of Jaynes theory, I recommend reading Jaynes's book (if you haven't already done so), as well as Reflections on the Dawn of Consciousness and The Julian Jaynes Collection.

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