Burst firing induces a slow after hyperpolarization in rat auditory thalamus.
The Ca2+-activated slow after hyperpolarization (sAHP) is found in many CNS regions where it may induce post-spike suppression of neuronal firing over many seconds. Nevertheless, the presence of sAHP in sensory thalamus remains uncertain. Here we show that a robust sAHP could be evoked in the rat medial geniculate body of auditory thalamus in vitro following a low-threshold Ca2+ spike and burst firing. The evoked sAHP exhibited kinetic and pharmacological features similar to that found elsewhere in the CNS. The sAHP was resistant to TTX or apamin but eliminated by muscarine. Furthermore, activation of low-threshold Ca2+ conductance alone is sufficient to induce the sAHP. Therefore, the membrane conductance underlying sAHP is functionally expressed in lemniscal thalamic relay neurons which may be preferably activated during burst firing.
Hu
B
B
Department of Clinical Neurosciences and Calgary Brain Institute, HMR Building, Room 170, Faculty of Medicine, University of Calgary, 3330 Hospital Drive N.W., Calgary, Alta., Canada T2N 4N1. hub@ucalgary.ca
Mooney
D M
DM
D000200:Action Potentials / Q000502:physiology* / Q000528:radiation effects; D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D004558:Electric Stimulation / Q000379:methods; D005829:Geniculate Bodies / Q000166:cytology*; D066298:In Vitro Techniques; D008297:Male; D009116:Muscarine / Q000494:pharmacology; D018721:Muscarinic Agonists / Q000494:pharmacology; D009474:Neurons / Q000502:physiology* / Q000528:radiation effects; D018408:Patch-Clamp Techniques / Q000379:methods; D051381:Rats; D020318:Rats, Long-Evans; D013779:Tetrodotoxin / Q000494:pharmacology
D000779:Anesthetics, Local; D018721:Muscarinic Agonists; D013779:Tetrodotoxin; D009116:Muscarine; D002118:Calcium