title: Functional synaptic contacts by intranuclear axon collaterals of thalamic relay neurons.
abstract: Relay neurons of the lateral geniculate nucleus innervate visual cortex, but they also provide axonal collaterals to neurons in the thalamic reticular nucleus, and these thalamic reticular neurons provide feedback inhibition to relay cells. An alternative source of inhibitory inputs onto geniculate relay neurons arises from intralaminar interneurons that provide feedforward inhibition via retinogeniculate innervation, and perhaps feedback inhibition via the corticothalamic pathway, analogous to that involving thalamic reticular neurons. Several reports indicate that relay neurons may also give rise to axonal collaterals within the lateral geniculate nucleus, constituting another route for feedback or local integration. We now provide new data indicating that collaterals from geniculate relay neurons provide excitatory input to local intralaminar interneurons and that this pathway may serve as a previously unknown means of local feedback inhibition. This circuitry could prove important in such activities as surround inhibition of receptive fields or increasing signal gain over noise.
authors.affiliation: Department of Neurobiology, State University of New York, Stony Brook, New York 11794-5230, USA. clcox@life.uiuc.edu
authors.forename: Charles L
authors.initials: CL
authors.lastname: Cox
authors.forename: Iva
authors.initials: I
authors.lastname: Reichova
authors.forename: S Murray
authors.initials: SM
authors.lastname: Sherman
mesh_terms: D000818:Animals; D001369:Axons / Q000648:ultrastructure*; D002415:Cats; D002478:Cells, Cultured; D003515:Cycloleucine / Q000031:analogs & derivatives* / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials; D025461:Feedback, Physiological; D005829:Geniculate Bodies / Q000166:cytology* / Q000502:physiology*; D007395:Interneurons / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D020646:Intralaminar Thalamic Nuclei / Q000166:cytology* / Q000502:physiology*; D009433:Neural Inhibition; D009434:Neural Pathways; D009474:Neurons / Q000166:cytology* / Q000502:physiology; D013569:Synapses / Q000187:drug effects / Q000502:physiology*
chemical_list: D003515:Cycloleucine; C036361:1-amino-1,3-dicarboxycyclopentane