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Morphology and connections of neurons in area 17 projecting to the extrastriate areas mt and 19DM and to the superior colliculus in the monkey Callithrix jacchus
Author(s) -
Weisenhorn D. M. Vogt,
Ilung R. B.,
Spatz W. B.
Publication year - 1995
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.903620207
Subject(s) - lucifer yellow , biology , efferent , superior colliculus , neuroscience , anatomy , callithrix , axon , dendritic spine , extrastriate cortex , pyramidal cell , visual cortex , population , afferent , primate , microbiology and biotechnology , intracellular , hippocampus , gap junction , demography , hippocampal formation , sociology
Neurons of area 17, the primary visual cortex, project to various anatomically and physiologically different extrastriate areas and subcortical regions. In the present investigation, we addressed the question of whether the efferent neurons in area 17 can contribute to functional diversity between these regions. We approached this question by analyzing the dendritic morphology of neurons in area 17 projecting to area MT, area 19DM, and the superior colliculus in the new world simian primate Callithrix jacchus , because dendritic morphology is an important factor in determinng physiological properties of nerve cells. Retrograde transport of fluorochromes injected into the target regions, and intracellular injections of Lucifer yellow in the prelabelled neurons, revealed the following. (1) Morphologically identical large pyramidal cells in layer VI of area 17 project to all three targets. Some of them possess axon collaterals to two or all three targets, suggesting that they provide common infcrmation to all three areas. (2) Pyramidal cells in layer IIIc projecting to area MT form a morphologically homogeneous population. (3) Three small to medium‐sized pyramidal cell types in layers IIIa‐c, spiny stellate cells in layer IIIc, and another large pyramidal cell type in layer VI project to area 19DM. (4) Pyramidal cells in the lower two‐thirds of layer V in area 17 project to the superior colliculus. In conclusion, we have shown that in Callithrix one efferent pathway may originate from several cell types. However, with the exception of the large cells in layer VI, efferent cells projecting to area MT, area 19DM, and the superior colliculus were morphologically distinct. This suggests that functional differences between brain regions could arise in part from morphological heterogeneity between and within the efferent cell populations. © Wiley‐Liss, Inc.