Cortical connections of the middle temporal and the middle temporal crescent visual areas in prosimian galagos (Otolemur garnetti)

Peter M. Kaskan, Jon H. Kaas

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

While considerable progress has been made in understanding the organization of visual cortex in monkeys, less is known about the visual systems of prosimians. The middle temporal visual area (MT), an area involved in motion perception, is common to all primates. We placed injections of tracers in MT and just caudal to MT in cortex expected to be the MT crescent (MTc), an area previously identified in monkeys but not in prosimians. We analyzed the patterns of projections in sections of the flattened cortex and used sections stained for cytochrome oxidase (CO) and myelin to identify the borders of MT, MTc, middle superior temporal (MST), superior temporal sulcus (FST), and V1 and V2 and to identify possible subdivisions of these areas. As in owl monkeys, MTc is a belt around most of MT that consists of a single row of CO-dense patches in a CO-light surround. Injections placed in MT revealed connections with V1, V2, V3, FST, MST, MTc, dorsomedial, dorsolateral (DL), posterior parietal cortex, and inferotemporal (IT) cortex. Injections localized to MTc displayed a slightly different pattern of connections with more involvement of DL and IT cortex, though other aspects, including patchy connections with V1 and V2, were similar to MT connections. The results indicate that prosimian galagos have an MT area with connection patterns that are similar to those in New and Old World monkeys. The MTc, initially described in owl monkeys, is present in galagos and is likely to be a common component of primate visual cortex.

Original languageEnglish (US)
Pages (from-to)349-366
Number of pages18
JournalAnatomical Record
Volume290
Issue number3
DOIs
StatePublished - Mar 2007
Externally publishedYes

Keywords

  • Evolution
  • Galago
  • Middle temporal
  • Middle temporal crescent
  • Visual cortex

ASJC Scopus subject areas

  • Anatomy
  • Biotechnology
  • Histology
  • Ecology, Evolution, Behavior and Systematics

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