Long-term potentiation in frontal cortex: role of NMDA-modulated polysynaptic excitatory pathways.
The present study examined the role of N-methyl-D-aspartic acid (NMDA) receptors in synaptic plasticity in regular-spiking cells of rat frontal cortex. Intracortical stimulation, at levels subthreshold for elicitation of action potentials, evoked a late excitatory postsynaptic potential (EPSP) in layer II-III neurons that was sensitive to the selective NMDA antagonist D-2-amino-5-phosphonovaleric acid (APV). This late EPSP showed marked short-term frequency-dependent depression, suggesting that it is polysynaptic in origin. Polysynaptic late EPSPs were selectively enhanced following high-frequency stimulation. This sustained increase in synaptic efficacy, or long-term potentiation, was expressed in regular spiking cells and appeared to result from activation of NMDA receptors on excitatory interneurons. These data demonstrate the existence of an NMDA-modulated polysynaptic circuit in the neocortex which displays several types of use-dependent plasticity.
Sutor
B
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Department of Neurology, Baylor College of Medicine, Houston, TX 77030.
Hablitz
J J
JJ
D015763:2-Amino-5-phosphonovalerate; D000818:Animals; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000187:drug effects; D005625:Frontal Lobe / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D066298:In Vitro Techniques; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors; D014633:Valine / Q000031:analogs & derivatives / Q000494:pharmacology
D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter; D015763:2-Amino-5-phosphonovalerate; D014633:Valine