Ultrastructural analysis of projections to the pulvinar nucleus of the cat. II: Pretectum.
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 gamma-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.
Baldauf
Zsolt B
ZB
Department of Anatomical Sciences and Neurobiology, University of Louisville, School of Medicine, Louisville, Kentucky 40292, USA.
Wang
Siting
S
Chomsung
Ranida D
RD
May
Paul J
PJ
Bickford
Martha E
ME
D000344:Afferent Pathways / Q000378:metabolism / Q000648:ultrastructure*; D000818:Animals; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism; D064026:Calbindins; D002415:Cats; D002452:Cell Count / Q000379:methods; D048429:Cell Size; D003911:Dextrans / Q000378:metabolism; D005968:Glutamate Decarboxylase / Q000378:metabolism; D007150:Immunohistochemistry / Q000379:methods; D016253:Microscopy, Immunoelectron / Q000379:methods; D008863:Microspheres; D016571:Neural Networks, Computer; D009474:Neurons / Q000145:classification / Q000378:metabolism / Q000648:ultrastructure*; D020649:Pulvinar / Q000378:metabolism / Q000648:ultrastructure*; D011963:Receptors, GABA-A / Q000378:metabolism; D064030:S100 Calcium Binding Protein G / Q000378:metabolism; D013477:Superior Colliculi / Q000378:metabolism / Q000648:ultrastructure*; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate / Q000378:metabolism
D029742:Caenorhabditis elegans Proteins; D064026:Calbindins; D003911:Dextrans; C469698:GAB-1 protein, C elegans; D011963:Receptors, GABA-A; D064030:S100 Calcium Binding Protein G; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; D005968:Glutamate Decarboxylase