Offensive Squid

I know some forum members would like to discuss and share in this.  I am hesitant to post it anywhere because it is not exactly art nor philosophy, although it would include those two areas itself.  Anyone have ideas or suggestions as to whether it should be its own sub-forum, as "Philosophy" is?

The general discussion is a bit crowded with a great assortment of stuff and I was hesitant to create the "Neuroscience" topic there.

A "Neuroscience" sub-forum could include anything related to that particular realm of science, or affiliated sciences & studies, physiology, psychology, vision, the brain, sensory perception, social issues, cyberbrains, wetcomputers,  color vision, synesthesia, stereoscopy, heterochromia, neurons, synapsis, ultraviolet, infrared, deadhead, cutting edge advances in restoring vision, and anything related to that such as even Peter's pithy topic suggestion about those cute mantis shrimps and their unusual vision regarding polarization…so one could even end up discussing the Blindsight retrofit misfits and Sarasti's visual acuity and difference…among other things & stuff!

We could even discuss cephalopodic sensory perception and the apparent intelligence of the Kleptopus!  The deep ocean rift depths are not the limit on this stuff!

Flanders said:

If you haven't read Oliver Sachs work on this subject–any of his books really, but I recommend Anthropologist on Mars specifically, and the Man Who Mistook His Wife for a Hat as well–you really should. It's very accessible, and looks into these very topics: the connection between the meat and the spirit, as it were, or how our brains affect what we see, and how that affects who we are.

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Thank you Flanders.   I have heard of Oliver Sachs but have not gottenaround to checking out his stuff.  But I will!

Post edited 4:37 am – August 31, 2010 by George Berger

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Philosophers have been interested in the phenomenon of blindsight since its formal recognition in 1974. I've had an interest in physiological psychology since 1969, so I read a bit about this weird function. It interests many philosophers since it seems to be a mode of visual awareness in the total absence of visual sensory experience. It occurs, for example, after damage to or ablation of Visual Area 1 (aka V1, primary visual cortex, striate cortex). I remember claims about the existence of a secondary, less important, visual input route from retina to superior colliculus. I did not read much about this, and indeed until recently I didn't know whether this pathway existed or whether it was an educated guess by scientists. The idea was that visual activation of the superior colliculus can elicit the behavioral responses reported in blindsight experiments without sensations, since the activation's pathway bypasses V1. In the 80s nothing I read or heard mentioned effects on other parts of the visual system (for good reason: their roles in vision were unclear, or they were as yet undiscovered).

 

Two weeks ago I read 'Blindsight depends on the lateral geniculate nucleus,' a Letter to Nature by Michael C. Schmidt et al first published online on 23 June 2010. Its importance cannot be overstated. It shows that '…the thalamic lateral geniculate nucleus (LGN) has a causal role in V1-independent processing of visual information.' The neural circuits remain unknown, but animal experiments show that in V1-lesioned cases, reversible inactivation of the LGN abolished fMRI and behavioural detection phenomena characteristic of blindsight. Activating LGN yielded V1-independent fMRI activation of (among others) extrastriate cortical areas V2, V3, V4, V5/MT. Then animals performed normally (i.e. without blindsight) at detection and location tasks. The conclusion reads, '…direct LGN projections to the extrastriate cortex have a critical functional contribution to blindsight.' The results '…suggest a viable pathway to mediate fast detection during normal vision.'  The paper also argues that the near-total abolition of activation following LGN shutdown indicates an inferior effect of the superior colliculus in such processes (so I learned that this pathway does exist).

 

This should interest materialists of all sorts. For it provides detail about the neural substrates of blindsight and normal vision. My roughly stated conclusion is that V1 is concerned with visual sensations to a far greater extent than any other visual area. One must admit however, that we still have no idea what a visual sensation is: is it epiphenomenal, is it identical to a detailed activation process in V1, is a reasonably intact V1 a necessary condition for some more complex brain process that is the sensation,  is it a nonphysical yet nonepiphenomenal entity of some sort, is it a new kind of physical entity? Although many materialists would prefer the second option, we can as yet conclude nothing more about them than what I just cautiously phrased. That's a bit of progress.