Synaptic potentials and effects of amino acid antagonists in the auditory cortex.
Neurons of in vitro guinea pig and rat auditory cortex receive a complex synaptic pattern of afferent information. As many as four synaptic responses to a single-stimulus pulse to the gray or white matter can occur; an early-EPSP followed, sequentially, by an early-IPSP, late-EPSP, and late-IPSP. Paired pulse stimulation and pharmacological studies show that the early-IPSP can modify information transmission that occurs by way of the early-EPSP. Each of these four synaptic responses differed in estimated reversal potential, and each was differentially sensitive to antagonism by pharmacological agents. DNQX (6,7-dinitroquinoxaline-2,3-dione), a quisqualate/kainate receptor antagonist, blocked the early-EPSP, and the late-EPSP was blocked by the NMDA receptor antagonist APV (D-2-amino-5-phosphonovalerate). The early-IPSP was blocked by the GABA-a receptor antagonist bicuculline, and the late-IPSP by the GABA-b receptor antagonists 2-OH saclofen or phaclofen. Presentation of stimulus trains, even at relatively low intensities, could produce a long-lasting APV-sensitive membrane depolarization. Also discussed is the possible role of these synaptic potentials in auditory cortical function and plasticity.
Cox
C L
CL
Department of Neuroscience, University of California, Riverside 92521.
Metherate
R
R
Weinberger
N M
NM
Ashe
J H
JH
D000596:Amino Acids / Q000037:antagonists & inhibitors*; D000818:Animals; D001303:Auditory Cortex / Q000502:physiology*; D005071:Evoked Potentials / Q000502:physiology; D058787:GABA-A Receptor Antagonists; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D008566:Membranes / Q000187:drug effects / Q000502:physiology; D008839:Microelectrodes; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology; D018377:Neurotransmitter Agents / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D017459:Receptors, Amino Acid; D011956:Receptors, Cell Surface / Q000037:antagonists & inhibitors; D011963:Receptors, GABA-A / Q000187:drug effects; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000187:drug effects; D013569:Synapses / Q000502:physiology*
D000596:Amino Acids; D058787:GABA-A Receptor Antagonists; D018377:Neurotransmitter Agents; D017459:Receptors, Amino Acid; D011956:Receptors, Cell Surface; D011963:Receptors, GABA-A; D016194:Receptors, N-Methyl-D-Aspartate