Notes

tags: #Blindsight #Consciousness #Visual-Awareness #Binocular-Rivarly

Blindsight patients seem to see without conscious awareness of it. What does this tell you about the role of V1 in visual awareness? And how does it relate, in your opinion, to other visual experiments that yielded data on the role of V1 in conscious vision?

V1 is the main telencephalic recipient of visual inputs in humans and primates. Indeed, chronic blindness and loss of conscious vision are often associated with lesions in this area. Experimental data on blindsight patients increased speculation on the generative role played by V1 in visual awareness. Although being one of the best-characterized areas of the primate cortex, its role in perception is still unclear. Among the existing theories, I support those relating awareness with ”hierarchical models” of the visual system, where higher-order extrastriate areas are considered the source of conscious vision.

So, is V1 directly contributing to conscious vision, or does its disruption impair the activity of higher visual areas, i.e., indirectly impeding awareness? crickAreWeAware1995 hinted that the neuroanatomy of monkeys makes improbable a direct perception of neuronal activity in V1, which could instead be possible in other visual cortical areas. A subsequent review of the topic (Tong, 2003) confirms the importance, but not sufficiency, of V1 for visual awareness. Many experiments on binocular rivalry phenomena investigate the alternation in perception between divergent monocular stimuli. In particular, studies of individual neurons in monkeys show that only a minority of cells in V1 present significant modulations in activity leopoldActivityChangesEarly1996. Hence, binocular rivalry likely derives from pattern competition in high-level extrastriate areas. Further experiments with blindsight patients from leopoldPrimaryVisualCortex2012 suggest that visual awareness can happen in spatial regions associated with a V1 lesion. Hence, the ”hierarchical model” theory gains relevance as the underlying process describing conscious vision.