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I've heard that the visual system is one of our slowest sensory systems.

How fast is the visual system, and how does it compare to other sensory systems (auditory, mechanosensory, pain, etc.)? For example, how long does it typically take for a visual stimulus from the external world to cause a neuron to fire in the V1 region of the cortex?

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2 Answers 2

researched with "sensory cortex latency" on google:

according nowak et al, latency in macaque v1 is ~75 ms, although there are cells with latency as short as 30 ms. according to camalier at al, latency in macaque A1 is more like 15-25 ms.

Also, see shriki et al for a computational perspective on latency coding in V1.

There is research into the latency of population responses recorded at the skin called "evoked potentials", reviewed by Nuwer. He says that there are evoked potentials over somatosensory cortex 20 ms after stimulus, whereas the potential over V1 is more like 100 ms after stimulus. All taken together, it does seem that the visual system is slower

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i don't have a good explanation for why the visual system would be slower because there are no direct periphery-cortical projections in any of these systems... –  honi May 5 at 21:11
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The visual stimulus has to go through photoreceptors and bipolar cells in the retina before the ganglion cell generates the action potential for the brain. That's one source or the slowdown. –  Victor Lyuboslavsky May 5 at 21:19
    
"the potential over V1 is more like 100 ms after stimulus." Wait, what? I get a peak of activity over V1 after about 100 ms in my MEG study. I've also seen reports of A1 effects at 15 ms or less after tone onset (early MLR response). –  Ana May 8 at 3:35
    
Although, now that I think about it, the MLR wouldn't be coming from A1, even though it would be measured on the scalp. –  Ana May 8 at 16:46
    
isn't a peak of activity the same as the time of the potential? –  honi May 8 at 16:52

Ahh, don't forget that there are 576 megapixels by each eye, at 35 frames per second... It's so fast, some researchs show that we need at least 50 milliseconds to process an image

Also it's well known that our auditory system is faster than the visual.

http://www.livescience.com/42666-human-brain-sees-images-record-speed.html

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I can find nothing to corroborate your 35fps assertion for the eye, but an, admittedly brief, search indicates that the fps of the eye is variable by lighting condition and training. –  Sam May 8 at 14:31

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