Synaptic modification in neurons of the central nucleus of the inferior colliculus.
Whole-cell patch clamp recordings were made from neurons in the central nucleus of the inferior colliculus (ICC) in brain slices from rat (8-13 days old). ICC neurons were classified by their discharge pattern in response to depolarizing and hyperpolarizing current injection. Excitatory postsynaptic currents (EPSCs) were elicited by stimulation of synaptic inputs under the condition that the synaptic inhibition was suppressed by strychnine and picrotoxin. EPSCs in all tested types of ICC neurons showed posttetanic, long-term potentiation (LTP) and long-term depression with tetanic stimulation. The potentiated EPSCs consisted of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor and NMDA receptor mediated components. The magnitude of LTP was larger when the intracellular concentration of the calcium buffer ethylene glycol-bis (beta-aminoethyl ether)-N,N,N',N'-tetracetic acid (EGTA) was lower and stimulation frequency was higher in cells with rebound firing patterns. Blocking N-methyl-D-aspartate (NMDA) receptors in rebound cells prevented generation of LTP. These results suggest that excitatory synaptic transmission in ICC neurons can be modified. LTP in the auditory midbrain may be important for activity-dependent, adaptive changes in response to normal and pathological stimulus conditions.
Wu
Shu Hui
SH
Laboratory of Sensory Neuroscience, Institute of Neuroscience, Life Sciences Research Center, Carleton University, 1125 Colonel By Drive, K1S 5B6, Ottawa, ON, Canada. shu_hui_wu@carleton.ca
Ma
Chun Lei
CL
Sivaramakrishnan
Shobhana
S
Oliver
Douglas L
DL
D000818:Animals; D001306:Auditory Pathways / Q000166:cytology / Q000378:metabolism; D004558:Electric Stimulation; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials; D066298:In Vitro Techniques; D007245:Inferior Colliculi / Q000166:cytology* / Q000378:metabolism*; D017774:Long-Term Potentiation / Q000187:drug effects; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D018408:Patch-Clamp Techniques; D051381:Rats; D020318:Rats, Long-Evans; D018091:Receptors, AMPA / Q000037:antagonists & inhibitors / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000378:metabolism; D013569:Synapses / Q000378:metabolism
D018691:Excitatory Amino Acid Antagonists; D018091:Receptors, AMPA; D016194:Receptors, N-Methyl-D-Aspartate