Widespread distribution of visual responsiveness in frontal, prefrontal, and prelimbic cortical areas of the cat: An electrophysiologic investigation

By using multiple-unit recording techniques, we explored the visual respons iveness of regions of cortex in and around the area described by others as the cat's "frontal eye fields" (Schlag J, Schlag-Rey M [1970] Brain Res 22: 1-13; Guitton D, Mandl G [1978] Brain Res 149:295-312; Pigarev IN [1984] Ne irofiziologiia 16:761-766). Our exploration included most of the cat's moto r areas (subdivisions of areas 4 and 6) as well as prefrontal and prelimbic regions. Visual responses were routinely obtained from portions of each of the areas we explored, including prefrontal and prelimbic cortex. The qual itative characteristics of visual responses appeared to vary with cytoarchi tectonic area. With few exceptions, receptive fields in these areas were la rge (most exceeding 2,500 deg(2)) and included the area centralis. Such lar ge fields and inclusion of central vision at nearly all sites precluded ret inotopic organization and prevented delineating distinct visual field repre sentations. The most reliable and robust visual activity was observed on th e ventral bank of the cruciate sulcus in area 6a alpha. The regions reporte d to correspond to the "frontal eye fields" did not exhibit any unique visu al properties that distinguished them from surrounding areas. The widesprea d distribution of visually driven activity we observed is consistent with t he known pattern of both cortical and subcortical inputs to this broad regi on of cortex. The observation of visually responsive activity across broad regions of cortex that is nominally motor is consistent with recent studies involving awake animals. (C) 1999 Wiley-Liss, Inc.