Dynamic circuitry for updating spatial representations. I. Behavioral evidence for interhemispheric transfer in the split-brain macaque

Rebecca A. Berman, Laura Heiser, Richard C. Saunders, Carol L. Colby

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

Internal representations of the sensory world must be constantly adjusted to take movements into account. In the visual system, spatial updating provides a mechanism for maintaining a coherent map of salient locations as the eyes move. Little is known, however, about the pathways that produce updated spatial representations. In the present study, we asked whether direct cortico-cortical links are required for spatial updating. We addressed this question by investigating whether the forebrain commissures-the direct path between the two cortical hemispheres-are necessary for updating visual representations from one hemifield to the other. We assessed spatial updating in two split-brain monkeys using the double-step task, which involves saccades to two sequentially appearing targets. Accurate performance requires that the representation of the second target be updated to take the first saccade into account. We made two central discoveries regarding the pathways that underlie spatial updating. First, we found that split-brain monkeys exhibited a selective initial impairment on double-step sequences that required updating across visual hemifields. Second, and most surprisingly, these impairments were neither universal nor permanent: the monkeys were ultimately able to perform the across-hemifield sequences and, in some cases, this ability emerged rapidly. These findings indicate that direct cortical links provide the main substrate for updating visual representations, but they are not the sole substrate. Rather, a unified and stable representation of visual space is supported by a redundant cortico-subcortical network with a striking capacity for reorganization.

Original languageEnglish (US)
Pages (from-to)3228-3248
Number of pages21
JournalJournal of Neurophysiology
Volume94
Issue number5
DOIs
StatePublished - Nov 2005
Externally publishedYes

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Split-Brain Procedure
Macaca
Haplorhini
Saccades

ASJC Scopus subject areas

  • Physiology
  • Neuroscience(all)

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Dynamic circuitry for updating spatial representations. I. Behavioral evidence for interhemispheric transfer in the split-brain macaque. / Berman, Rebecca A.; Heiser, Laura; Saunders, Richard C.; Colby, Carol L.

In: Journal of Neurophysiology, Vol. 94, No. 5, 11.2005, p. 3228-3248.

Research output: Contribution to journalArticle

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