Functional specificity of callosal connections in tree shrew striate cortex

William H. Bosking, Robert Kretz, Michele L. Pucak, David Fitzpatrick

Research output: Contribution to journalArticle

Abstract

Although callosal connections have been shown to link extensive regions of primary visual cortex, the distribution of these connections with respect to the map of visual space and the map of orientation preference remains unclear. Here we combine optical imaging of intrinsic signals with injection of fluorescent microspheres to assess the functional specificity of callosal connections in the tree shrew. By imaging both hemispheres simultaneously while presenting a series of spatially restricted stimuli, we find that a substantial region of visual space is represented bilaterally. Each hemisphere includes a representation of the ipsilateral visual field that is highly compressed relative to that of the contralateral visual field and is most extensive in the lower visual field, where ~30°of central visual space are represented bilaterally. Callosal connections extend throughout the region of bilateral representation but terminate in a spatially restricted manner that links visuotopically corresponding sites in the two hemispheres. In contrast, callosal connections appear to terminate without regard for the map of orientation preference, showing little sign of the orientation- specific modular and axial specificity that is characteristic of long-range horizontal connections. By coordinating the activity in the two hemispheres in a way that preserves nearest neighbor relationships, callosal connections may best be viewed as elements of local circuits that operate within a single bilateral representation of visual space.

Original languageEnglish (US)
Pages (from-to)2346-2359
Number of pages14
JournalJournal of Neuroscience
Volume20
Issue number6
StatePublished - Mar 15 2000

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Keywords

  • Corpus callosum
  • Horizontal connections
  • Intrinsic signals
  • Ipsilateral visual field
  • Optical imaging
  • Orientation selectivity
  • Visual cortex
  • Visual field
  • Visuotopic

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Bosking, W. H., Kretz, R., Pucak, M. L., & Fitzpatrick, D. (2000). Functional specificity of callosal connections in tree shrew striate cortex. Journal of Neuroscience, 20(6), 2346-2359.