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Anatomical banding of intrinsic connections in striate cortex of tree shrews ( Tupaia glis )
Author(s) -
Rockland K. S.,
Lund J. S.,
Humphrey A. L.
Publication year - 1982
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.902090105
Subject(s) - biology , axon , horseradish peroxidase , striate cortex , orientation column , visual cortex , anatomy , soma , neuroscience , cortex (anatomy) , axoplasmic transport , biochemistry , enzyme
The intrinsic connectivity of striate cortex was investigated by injecting horseradish peroxidase (HRP) into this area in tree shrews. Such HRP injections demonstrated periodically organized, stripelike connections within area 17. These stripes occur in layers I–IIIA and consist of a small number of retrogradely filled neurons, some clearly pyramidal, together with HRP‐labeled axon terminals. HRP‐filled axon trunks run between labeled stripes, interconnecting adjacent and distant regions of the stripe pattern. Correlation with Golgi‐stained tissue suggests that these stripes are horizontally interconnected by pyramidal neurons with long intracortical axon collaterals (followed for distances over 1 mm form the soma). The HRP‐labeled stripes measure about 230 μm in width, with a center‐to‐center repeat distance of 450–500 μm. They have been mapped over an 8 mm 2 area of striate cortex and would thus seem capable of effecting lateral interactions over considerable portions of the retinotopic map. In their dimensions and overall pattern, these anatomical stripes resemble the 2‐deoxyglucose (2‐DG) bands resulting from visual stimulation of tree shrews with stripes of a single orientation. While the functional role of the HRP‐labeled stripes is unclear, their similarities with the 2‐DG pattern raise the intriguing possibility that they may be related to orientation selectivity. The striking regularity of these extensive lateral interconnections emphasizes the importance of horizontal intralaminar connections within the cortex.