Projections to early visual areas V1 and V2 in the calcarine fissure from parietal association areas in the macaque
Name
Borra-2011-Projections to early visual areas V1 and V2.pdf
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1.97 MB
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Author(s)
Rockland, Kathleen
Borra, Elena
Date Issued
June 2011
Journal
Frontiers in Neuroanatomy
Publisher
Frontiers Research Foundation
Citation
Borra, Elena, and Kathleen S. Rockland. “Projections to Early Visual Areas V1 and V2 in the Calcarine Fissure from Parietal Association Areas in the Macaque.” Frontiers in Neuroanatomy 5 (2011). © 2011 Frontiers Media S.A.
Version
Final published version
Abstract
Non-extrastriate projections to area V1 in monkeys, now demonstrated by several anatomical studies, are potential substrates of physiologically documented multisensory effects in primary sensory areas. The full network of projections among association and primary areas, however, is likely to be complex and is still only partially understood. In the present report, we used the anterograde tracer biotinylated dextran amine to investigate projections to areas V1 and V2 from subdivisions of the parietal association cortex in macaque. Parietal cortex was chosen to allow comparisons between projections from this higher association area and from other previously reported areas. In addition, we were interested in further elucidating pathways to areas V1 and V2 from parietal areas, as potentially contributing to attention and active vision. Of eight cases, three brains had projections only to area V2, and the five others projected to both areas V1 and V2. Terminations in area V1 were sparse. These were located in supragranular layers I, II, upper III; occasionally in IVB; and in layer VI. Terminations in V2 were denser, and slightly more prevalent in the supragranular layers. For both areas, terminations were in the calcarine region, corresponding to the representation of the peripheral visual field. By reconstructions of single axons, we demonstrated that four of nine axons had collaterals, either to V1 and V2 (n = 1) or to area V1 and a ventral area likely to be TEO (n = 3). In area V1, axons extended divergently in layer VI as well as layer I. Overall, these and previous results suggest a nested connectivity architecture, consisting of multiple direct and indirect recurrent projections from association areas to area V1. Terminations in area V1 are not abundant, but could be potentiated by the network of indirect connections.
MIT Department
Massachusetts Institute of Technology. Department of Brain and Cognitive Sciences
RIKEN-MIT Center for Neural Circuit Genetics
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Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported
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DOI of Published Version
https://doi.org/10.3389/fnana.2011.00035
