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Ultrastructural analysis of projections to the pulvinar nucleus of the cat. II: Pretectum
Author(s) -
Baldauf Zsolt B.,
Wang Siting,
Chomsung Ranida D.,
May Paul J.,
Bickford Martha E.
Publication year - 2005
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.20487
Subject(s) - gabaergic , pretectal area , neuroscience , nucleus , postsynaptic potential , biology , calbindin , thalamus , anatomy , central nervous system , inhibitory postsynaptic potential , immunohistochemistry , midbrain , receptor , biochemistry , immunology
The pretectum (PT) can supply the pulvinar nucleus (PUL), and concomitantly the cortex, with visual motion information through its dense projections to the PUL. We examined the morphology and synaptic targets of pretecto‐pulvinar (PT‐PUL) terminals labeled by anterograde transport in the cat. By using postembedding immunocytochemical staining for γ‐aminobutyric acid (GABA), we additionally determined whether PT‐PUL terminals or their postsynaptic targets were GABAergic. We found that the main projection from the PT to the PUL is an ipsilateral, non‐GABAergic projection (72.4%) that primarily contacts thalamocortical cell dendrites (87.6%), and also the dendritic terminals of interneurons (F2 profiles; 12.4%). The PT additionally provides GABAergic innervation to the PUL (27.6% of the ipsilateral projection), which chiefly contacts relay cell dendrites (84.6%) but also GABAergic profiles (15.4%). These GABAergic pretectal terminals are smaller, beaded fibers that likely branch to bilaterally innervate the PUL and dLGN, and possibly other targets. We also examined the neurochemical nature of PT‐PUL cells labeled by retrograde transport and found that most are non‐GABAergic cells (79%) and devoid of calbindin. Taking existing physiological and our present morphological data into account, we suggest that, in addition to the parietal cortex, the non‐GABAergic PT‐PUL projection may also strongly influence PUL activity. The GABAergic pretectal fibers, however, may provide a more widespread influence on thalamic activity. J. Comp. Neurol. 485:108–126, 2005. © 2005 Wiley‐Liss, Inc.