Overview of Sensory Systems of Tarsius Peiyan Wong & Christine E.Collins & Jon H. Kaas Received: 16 April 2009 / Accepted: 28 October 2009 / Published online: 19 January 2010 # Springer Science+Business Media, LLC 2010 AbstractTarsiers form the sister taxon to anthropoid primates, and theirbrains possess a mix of primitive and specialized features. We describe architectonically distinct subdivisions of the somatosensory, auditory, and visual systems for ta as wellas nocturnal New World owlmonkeys (Aotus) and strepsirhine galagos (Otolemur) for comparison. In general, the dorsal column nuclei, the ventropo nucleus, and primary somatosensory cortex are somewhat less distinctly differenti- ated in tarsiers, suggesting that the somatosensory system is less specialized for somatosensory processing. Although the inferior colliculus and the medial gen complex of the auditory system are architectonically similar across the 3 prim the primary auditory cortex of tarsiers is more distinct, suggesting a greater role in auditory cortical processing. In the visual system, the differentiation of the superior colliculus is similar in all 3 primates, whereas the laminar pattern in the lateral geniculate nucleus and the subdivisions of the inferior pulvinar in tarsiers rese thoseof anthropoid primates ratherthan strepsirhines, in agreement with the evidence that tarsiers form the sister clade foranthropoids. In addition, primary visual cortex has more distinct sublayers in tarsiers than other primates, attesting to its importance in this visual predator. Overall,tarsiers have well developed visual and auditory systems, and a less well developed somatosensory system, suggesting an enhanced reliance on the visual and auditory senses, rather than somatosensory sense. Keywordsauditory cortex . cortical areas . lateral geniculate nucleus . medial geniculate nucleuprimates . somatosensory cortex . ventroposterior nucleus . visual cortex Int J Primatol (2010) 31:1002–1031 DOI 10.1007/s10764-009-9388-4 P. Wong : C. E. Collins : J. H. Kaas (*) Department of Psychology, Vanderbilt University, Nashville, TN 37240, USA e-mail: jon.kaas@vanderbilt.edu