The middle temporal visual area (MT) in the bushbaby, Galago senegalensis

Abstract

Recently we discovered a topographic representation of the visual field in the temporal cortex of the owl monkey, Aotus trivirgatus, which we termed the 'middle temporal visual area' (MT). Such a systematic representation has not yet been demonstrated in the temporal cortex of other primates, although the probable existence of MT is indicated in several other primates by fiber connection patterns, architectonic characteristics, and cortical evoked potentials. We attempted to identify MT in the bushbaby, Galago senegalensis, because we wondered if this temporal visual area arose early in primate (or mammalian) evolution or was restricted to the Anthropoidea. Also, a projection from the inferior pulvinar to cortex in the expected location of MT has been demonstrated in the bushbaby. Since cortical projections from the pulvinar have been regarded as a major source of visual input to temporal 'association' cortex, it seemed important to explore the organization of this projection zone of the inferior pulvinar in the bushbaby.