The afferent and efferent callosal connections of retinotopically defined areas in cat cortex

Journal Article · Sun Aug 01 04:00:00 EDT 1982 · J. Neurosci.; (United States)

OSTI ID:6578903

Segraves, M A; Rosenquist, A C

We compared the callosal afferent and efferent connections of different retinotopic loci within a given visual cortical area as well as the connectivity patterns among similar retinotopic loci in different visual areas. Small injections (75 nl) of a mixture of horseradish peroxidase and (/sup 3/H)leucine were made through a recording pipette at injection sites identified by retinotopic mapping. A small locus of cortex within a callosally connected region had precise reciprocal connections with the homotopic locus in the contralateral hemisphere. This small locus also was callosally connected with a variable number of heterotopic loci. Both reciprocal and nonreciprocal heterotopic callosal connections were found. Homotopic and heterotopic connections appeared to have a high degree of retinotopic fidelity. Precisely homotopic connections were present not only between locations on the vertical meridian representations at the left and right area 17/18 borders but also, for example, between mirror-symmetrical points on the peripheral horizontal meridian representation in the left and right posteromedial lateral suprasylvian areas. In several experiments, we found that both callosal neurons and terminals in the homotopic cortex were grouped into two to three distinct clusters ranging from 600 to 900 micrometers in width. Callosal neurons with homotopic connections were primarily pyramidal cells in lower layer III and upper layer IV. Outside of areas 17 and 18, there was a significant number of pyramidal and fusiform-shaped callosal neurons in layers V and VI. The majority of callosal terminals were located in layers II, III, and IV.

• Research Organization: Department of Anatomy, University of Pennsylvania, Philadelphia
• OSTI ID: 6578903
• Journal Information: J. Neurosci.; (United States), Journal Name: J. Neurosci.; (United States) Vol. 2:8; ISSN JNRSD
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
ANIMAL CELLS
ANIMALS
BIOCHEMISTRY
BODY
BODY AREAS
BRAIN
CARBOXYLIC ACIDS
CATS
CENTRAL NERVOUS SYSTEM
CEREBRAL CORTEX
CEREBRUM
CHEMISTRY
EYES
FACE
HEAD
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LEUCINE
MAMMALS
MORPHOLOGY
NERVE CELLS
NERVOUS SYSTEM
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
PHYSIOLOGY
RETINA
SENSE ORGANS
SOMATIC CELLS
TRITIUM COMPOUNDS
VERTEBRATES
VISION