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If a brain is exposed to an intermittent light are specific areas going to fire? If yes, which of them? Is there any experiment about this?

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What do you mean? Cutting open a skull and shining light into it? Why would the brain's cells be able to sense light? Even if they did, how could we possibly answer your question without knowing which areas of the brain you were illuminating? –  terdon Nov 13 '13 at 19:46
    
as @terdon said, just shining light on the brain wont make it sense it (unless of course it is a laser of sorts which causes a lesion :P) . You need photoreceptors for sensing light. In fact I have heard that brain doesnt have mechanoreceptors and nociceptors so someone wont feel that their brain is being cut <read and seen it in the Hannibal (by Thomas Harris): Not a very reliable source, though :P >. –  WYSIWYG Nov 14 '13 at 11:34

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It is thought that there are no active optical receptors in the brain normally, its possible some effect might show up in the future, it would be minor at best.

Shining light into the brain is standard procedure in optogenetics experiments. A subpopulation of neurons is transformed to express an optical receptor to modulate genetic or signalling properties of the cell.

So the reason I say it would be small effect on a native brain is that these experiments do give good results and are run with controls which do not have the optical receptors added, which typically show no change in brain activity.

optogenetic modulation of activity in a rat prefrontal cortex

Channelrhodopsin-2 (ChR2) induces temporally precise blue light-driven activity in rat prelimbic prefrontal cortical neurons. a) In vitro schematic (left) showing blue light delivery and whole-cell patch-clamp recording of light-evoked activity from a fluorescent CaMKllα::ChR2-EYFP expressing pyramidal neuron (right) in an acute brain slice. b) In vivo schematic (left) showing blue light (473 nm) delivery and single-unit recording. (bottom left) Coronal brain slice showing expression of CaMKllα::ChR2-EYFP in the prelimbic region. Light blue arrow shows tip of the optical fiber; black arrow shows tip of the recording electrode (left). White bar, 100 µm. (bottom right) In vivo light recording of prefrontal cortical neuron in a transduced CaMKllα::ChR2-EYFP rat showing light-evoked spiking to 20 Hz delivery of blue light pulses (right). Inset, representative light-evoked single-unit response.

Image taken from the linked Wikipedia page and originally from Baratta et al..

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