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If you look at the visual system[1] the signal passes through many preliminary nodes before it reaches the back of the brain aka the visual cortex (which is res

If you look at the visual system[1] the signal passes through many preliminary nodes before it reaches the back of the brain aka the visual cortex (which is responsible for the conscious visual field, i.e. "seeing"). For example, one of these preliminary nodes is the Superior colliculus, which is part of the 'midbrain'[2]: > The general function of the tectal system is to direct behavioral responses toward specific points in egocentric ("body-centered") space. Each layer of the tectum contains a topographic map of the surrounding world in retinotopic coordinates, and activation of neurons at a particular point in the map evokes a response directed toward the corresponding point in space. [...] > Even in primates, however, the tectum is also involved in generating spatially directed head turns, arm-reaching movements, shifts in attention that do not involve any overt movements. [...] > Thus, cats with major damage to the visual cortex cannot recognize objects, but may still be able to follow and orient toward moving stimuli, although more slowly than usual. That is just one of the preliminary areas. The SC is part of the brainstem. People think of the brainstem as just controlling essential functions like breathing, but it's also capable of more complex motor function. [1]: https://upload.wikimedia.org/wikipedia/commons/7/7e/Gray722-svg.svg https://upload.wikimedia.org/wikipedia/commons/7/7e/Gray722-... [2]: https://en.wikipedia.org/wiki/Superior_colliculus#Function https://en.wikipedia.org/wiki/Superior_colliculus#Function

KingMob 11y ago
I studied blindsight in grad school, and actually analyzed the data of patient GY, probably the most widely-studied blindsight patient. I forget the authors, but there was an anatomical paper showing that blindsight requires all the secondary connections in order to happen. So, everything from the retina synapses onto the thalamus first, and then 97+% goes on to the primary visual cortex. The last few percent go to areas like the SC, the frontal eye field, and V5/MT. This paper showed that if the damage was prior to, or including the thalamus, no blindsight was ever shown, but if the damage was between the thalamus and V1, or involving V1 itself, blindsight was possible. The real question still is, why are these minor regions capable of supporting tasks, but not experience?

KingMob 11y ago

I studied blindsight in grad school, and actually analyzed the data of patient GY, probably the most widely-studied blindsight patient. I forget the authors, but there was an anatomical paper showing that blindsight requires all the secondary connections in order to happen. So, everything from the retina synapses onto the thalamus first, and then 97+% goes on to the primary visual cortex. The last few percent go to areas like the SC, the frontal eye field, and V5/MT. This paper showed that if the damage was prior to, or including the thalamus, no blindsight was ever shown, but if the damage was between the thalamus and V1, or involving V1 itself, blindsight was possible. The real question still is, why are these minor regions capable of supporting tasks, but not experience?