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closewhat are our orientation columns for? other animals don't have them
Posted by sydneyunivisphys on 08 Jun 2007 at 23:27 GMT
Most neurons in the primary visual cortices of nocturnal (rats) and diurnal (squirrels) rodents are orientation-selective like those in carnivores (e.g. cats, ferrets, minks), scandentia (tree shrews) and primates but neurons in the rodents selective for similar orientation are not clustered together (no orientation columns). Ringach's model simulates the detailed way in which primate and cat oriented cells are clustered but the success of rodent species suggests that perhaps this organization is just not very important. In seeking to explain orientation maps are we wasting a lot of energy trying to explain something that has little functional consequence? Or is it actually critical functionally for the way primate cortex processes visual signals, with the rodent just having a completely different way of doing things?
RE: what are our orientation columns for? other animals don't have them
dario replied to sydneyunivisphys on 11 Jun 2007 at 21:02 GMT
These are all good points...
I would argue that the question of HOW the maps are wired is different from the question of WHY they exist. The article addresses only the first question and is agnostic as to the second.
Nevertheless, as you've already asked, I must agree that mounting evidence suggests that maps may not be very important for normal visual function after all.
A compelling argument for this view is put forward in Jonathan Horton's review "The cortical column: a structure without function" (cited in the paper), one that I highly recommend.
I do not agree, however, that this means that studying how maps (when they exist) and receptive fields get wired is a 'waste of time'. For example, one could argue that the fact that maps may naturally emerge as a consequence of a simply wiring mechanism (without much 'effort') supports the view that they may not be critical for normal visual processing.