Selective GABAergic control of higher-order thalamic relays.
GABAergic signaling is central to the function of the thalamus and has been traditionally attributed primarily to the nucleus reticularis thalami (nRT). Here we present a GABAergic pathway, distinct from the nRT, that exerts a powerful inhibitory effect selectively in higher-order thalamic relays of the rat. Axons originating in the anterior pretectal nucleus (APT) innervated the proximal dendrites of relay cells via large GABAergic terminals with multiple release sites. Stimulation of the APT in an in vitro slice preparation revealed a GABA(A) receptor-mediated, monosynaptic IPSC in relay cells. Activation of presumed single APT fibers induced rebound burst firing in relay cells. Different APT neurons recorded in vivo displayed fast bursting, tonic, or rhythmic firing. Our data suggest that selective extrareticular GABAergic control of relay cell activity will result in effective, state-dependent gating of thalamocortical information transfer in higher-order but not in first-order relays.
Bokor
Hajnalka
H
Institute of Experimental Medicine, Hungarian Academy of Sciences, P.O. Box 67, 1450 Budapest, Hungary.
Frère
Samuel G A
SG
Eyre
Mark D
MD
Slézia
Andrea
A
Ulbert
István
I
Lüthi
Anita
A
Acsády
László
L
D000200:Action Potentials / Q000502:physiology; D000344:Afferent Pathways / Q000502:physiology* / Q000648:ultrastructure; D000818:Animals; D001710:Biotin / Q000031:analogs & derivatives*; D048430:Cell Shape / Q000502:physiology; D003712:Dendrites / Q000502:physiology / Q000648:ultrastructure; D003911:Dextrans; D004558:Electric Stimulation; D007150:Immunohistochemistry; D008297:Male; D008636:Mesencephalon / Q000502:physiology* / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D009433:Neural Inhibition / Q000502:physiology*; D009924:Organ Culture Techniques; D010320:Parvalbumins / Q000378:metabolism; D010835:Phytohemagglutinins; D017729:Presynaptic Terminals / Q000502:physiology / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D011963:Receptors, GABA-A / Q000187:drug effects / Q000378:metabolism; D009435:Synaptic Transmission / Q000502:physiology*; D013788:Thalamus / Q000502:physiology* / Q000648:ultrastructure; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D003911:Dextrans; D010320:Parvalbumins; D010835:Phytohemagglutinins; D011963:Receptors, GABA-A; C076397:biotinylated dextran amine; C100156:leukoagglutinins, plants; C070614:neurobiotin; D005680:gamma-Aminobutyric Acid; D001710:Biotin