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Brain Struct Funct. 2018 Oct 4. doi: 10.1007/s00429-018-1764-4. [Epub ahead of print]

Unidirectional monosynaptic connections from auditory areas to the primary visual cortex in the marmoset monkey.

Author information

1
Laboratory of Neuroinformatics, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 02-093, Warsaw, Poland.
2
Monash University Node, Australian Research Council, Centre of Excellence for Integrative Brain Function, Clayton, VIC, 3800, Australia.
3
Monash University Node, Australian Research Council, Centre of Excellence for Integrative Brain Function, Clayton, VIC, 3800, Australia. marcello.rosa@monash.edu.
4
Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, VIC, 3800, Australia. marcello.rosa@monash.edu.
5
Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, VIC, 3800, Australia.
6
Laboratory for Marmoset Neural Architecture, RIKEN Center for Brain Science, Saitama, 351-0106, Japan.
7
Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, 11724, USA.
8
School of Rural Health, Monash University, Churchill, VIC, 3842, Australia.
9
Department of Physiology, Keio University School of Medicine, Tokyo, 160-8582, Japan.
10
Monash University Node, Australian Research Council, Centre of Excellence for Integrative Brain Function, Clayton, VIC, 3800, Australia. parthaxmitra@gmail.com.
11
Laboratory for Marmoset Neural Architecture, RIKEN Center for Brain Science, Saitama, 351-0106, Japan. parthaxmitra@gmail.com.
12
Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, 11724, USA. parthaxmitra@gmail.com.

Abstract

Until the late twentieth century, it was believed that different sensory modalities were processed by largely independent pathways in the primate cortex, with cross-modal integration only occurring in specialized polysensory areas. This model was challenged by the finding that the peripheral representation of the primary visual cortex (V1) receives monosynaptic connections from areas of the auditory cortex in the macaque. However, auditory projections to V1 have not been reported in other primates. We investigated the existence of direct interconnections between V1 and auditory areas in the marmoset, a New World monkey. Labelled neurons in auditory cortex were observed following 4 out of 10 retrograde tracer injections involving V1. These projections to V1 originated in the caudal subdivisions of auditory cortex (primary auditory cortex, caudal belt and parabelt areas), and targeted parts of V1 that represent parafoveal and peripheral vision. Injections near the representation of the vertical meridian of the visual field labelled few or no cells in auditory cortex. We also placed 8 retrograde tracer injections involving core, belt and parabelt auditory areas, none of which revealed direct projections from V1. These results confirm the existence of a direct, nonreciprocal projection from auditory areas to V1 in a different primate species, which has evolved separately from the macaque for over 30 million years. The essential similarity of these observations between marmoset and macaque indicate that early-stage audiovisual integration is a shared characteristic of primate sensory processing.

KEYWORDS:

Audiovisual integration; Auditory cortex; Connections; Primate; Striate cortex

PMID:
30288557
DOI:
10.1007/s00429-018-1764-4

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