Visual and somatosensory receptive fields of neurons in the squirrel monkey pulvinar

Abstract

Visual and somatosensory responses were studied in 329 neurons in the pulvinar of the squirrel monkey. Almost all somatosensory neurons (total= 46) in pulvinar lateralis (PL); most had continuous peripheral fields, though a few were bilaterally activated. Visual neurons (total= 179) were found in PL, pulvinar inferior (PI) and pulvinar medialis (PM). Of these, 29 responded only to diffuse illumination, while 150 had definable receptive fields. Approximately twice as many neurons in PI were responsive to light than neurons in PL or PM. The majority of visual units was responsive to some form of moving stimulus, and for some neurons there were additional specificities for directionality and orientation. Most visual neurons were monocularly driven (75%); nearly all visual units which could be mapped had receptive fields within 25° of the fovea. The majority of fields was in the visual hemifield contralateral to the recording electrode. Most visual neurons had receptive fields of at least 100 sq. degrees in area. A third group of 104 neurons was found unresponsive to visual and somatosensory stimuli.