If nothing about the optic radiation from the LGN to V1 changes, then V1 units that normally would have received inputs from corresponding regions in space from the two eyes will end up receiving inputs from potentially widely separated Selleckchem LDN 193189 regions, mirrored across the vertical midline, from the same eye. While this explanation accounts for the basic findings from Hoffmann et al., it leaves open the issue

of fine-scale reorganization. What is the nature of response properties at the level of single V1 units? The pRFs show a bilobed structure straddling the midline, but does this hold true for individual neurons as well? Let us consider a potential behavioral consequence of this possibility. If every neuron were unable to distinguish between two mirror-imaged locations (and for every lobe position pair, the ambiguity were the same for all neurons sensitive to either of those two locations, i.e., every neuron that had an rf lobe at location “A” necessarily had another lobe at the mirror-symmetric

location “B”), then the ambiguity would be unresolvable and would become manifest at the level Regorafenib order of behavior, i.e., a person with such an rf organization would confuse left and right. However, as Hoffmann et al. (2012) and earlier researchers (Victor et al., 2000) report, no such confusions are apparent, suggesting that

neurons do code for specific locations unambiguously. The observed bilobed structure of pRFs may be caused by the clustering of neurons with unilobed rfs at one or the other mirror-symmetric positions. A classical Hebbian learning-based account (Hebb, 1949) also argues for unilobed rfs at the level of individual neurons in achiasma. In the normal visual pathway, with appropriate decussation of optic fibers at HA 1077 the chiasm, a given neuron in V1 would receive inputs from the two eyes from spatially close (or even identical) locations in the visual field. This proximity would lead to a temporal pattern of stimulation ideally suited for Hebbian reinforcement of connections (since the inputs from the two locations would be temporally highly correlated). A binocular V1 cell would be the result. However, in achiasma, the same fibers from LGN coincident on any location in V1 carry information from two very disparate parts of the visual field. The temporal activity in these fibers is likely to be largely uncorrelated and to provide no support for coupling via Hebbian reinforcement. Individual V1 neurons, therefore, would be driven by one or the other of these fibers but not by both, leading to single-lobed rfs. It will be important for future neurophysiological studies to empirically verify this theoretical prediction.