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The distribution of the sensory input in the dorsal spinal cord of the tortoise
Author(s) -
Rosenberg M. E.
Publication year - 1974
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.901560104
Subject(s) - spinal cord , anatomy , biology , dorsum , postsynaptic potential , neuroscience , tortoise , french horn , sensory system , cord , physics , geometry , paleontology , biochemistry , receptor , mathematics , acoustics
The functional distribution of dorsal horn structures in the lumbo‐sacral spinal cord of the tortoise ( T. graeca, T. hermanni ) was determined by surface mapping of the cord dorsum potential in the decerebrate animal. Electrical stimuli were applied to either skin, peripheral nerve, dorsal roots or dorsal tracts. It was shown that the cord dorsum potential in this reptile could be interpreted in the same way as that in the mammal; this permitted identification of the primary volley separately from the consequent activity of post‐synaptic structures within the dorsal horn. The longitudinal distribution of post‐synaptic activity suggested that the associated structures are not distributed uniformly along the cord but rather have concentration maxima within segments in regions just rostral to the root entry zones. Combined transverse and longitudinal mapping revealed streaming of postsynaptic activity, traced over two or three segments, towards the mid line, when proceeding rostrally from a given root entry zone. The fact that this occurred for successive roots suggests that somatotopic representation exists in the transverse plane within the dorsal horn. The longitudinal distribution of post‐synaptic activity suggested that the associated structures are not distributed uniformly along the cord but rather have concentration maxima within segments in regions just rostral to the root entry zones. Combined transverse and longitudinal mapping revealed streaming of post‐synaptic activity, traced over two or three segments, towards the mid line, when proceeding rostrally from a given root entry zone. The fact that this occurred for successive roots suggests that somatotopic representation exists in the transverse plane within the dorsal horn.