Monday, July 10, 2006

V1 and imagination

Small Grey Matters has a post related to an experimental finding that there is an activation in V1- the striate cortex- when the subjects make motor responses to an earlier presented visual stimuli (this is the delayed response situation as in the post/ experiment). Also, this activation is not present in higher visual cortical areas and thus is a result of bottom-up processes. One speculation as to the presence of this activation about the same time as the motor response is that when making the response one needs to 'bring back to memory' or imagine the earlier presented stimuli (or the no-stimuli screen) and that bringing such image back to mind is necessary for the subjects to decide whether the stimuli was present or not.

Thus, a particular mechanism for explaining this activation could be that it is related to imagining the earlier-presented stimuli and is distinguished from the actual visual experience by lack of activation in higher visual areas. The 'imaginative center' of the brain may send inhibitory signals to the higher visual cortical areas so that this appears as imagination and not as actual hallucinatory delayed visual stimuli.

Just speculation, but speculations that could be verified if supporting experiments are conducted by someone.

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