Visual behavior following lesion of phasic W-fibers in the cat's optic tract

This chapter discusses the behavioral results gathered in animals that underwent a superficial lesion of the optic tract (OT), removing a vast majority of phasic W-fibers and part of the Y-fibers, but almost entirely sparing X-fibers and tonic W-fibers. Pattern was tested and discrimination learning was done to find out whether a total removal of the phasic W-input interferes with higher level visual functions. An additional reason for testing pattern and form was to test Sherman's ideas on the crucial role of the Y-system for form perception in animals with a sizeable decrease of Y-input. Finally, given that the Y-system is widely considered to be important for temporal resolution flicker discrimination is tested at various flicker rates and at various levels of stimulus luminance. The results seem to show a promising dissociation of symptoms following transection of the superficial portion of the OT— that is, an impairment of temporal resolution and a substantial integrity of spatial discrimination functions, as witnessed by an unimpaired discrimination of bars of different contrast and spatial frequency. © 1993, Academic Press Inc