NMDA receptors are essential for the acquisition, but not expression, of conditional fear and associative spike firing in the lateral amygdala.
We examined the contribution of N-methyl-D-aspartate (NMDA) receptors (NMDARs) to the acquisition and expression of amygdaloid plasticity and Pavlovian fear conditioning using single-unit recording techniques in behaving rats. We demonstrate that NMDARs are essential for the acquisition of both behavioral and neuronal correlates of conditional fear, but play a comparatively limited role in their expression. Administration of the competitive NMDAR antagonist +/--3-(2-carboxypiperazin-4-yl) propyl-1-phosphonic acid (CPP) prior to auditory fear conditioning completely abolished the acquisition of conditional freezing and conditional single-unit activity in the lateral amygdala (LA). In contrast, CPP given prior to extinction testing did not affect the expression of conditional single-unit activity in LA, despite producing deficits in conditional freezing. Administration of CPP also blocked the induction of long-term potentiation in the amygdala. Together, these data suggest that NMDARs are essential for the acquisition of conditioning-related plasticity in the amygdala, and that NMDARs are more critical for regulating synaptic plasticity and learning than routine synaptic transmission in the circuitry supporting fear conditioning.
Goosens
Ki A
KA
Department of Psychology, University of Michigan, Ann Arbor, Michigan 48109-1109, USA.
Maren
Stephen
S
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000679:Amygdala / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001522:Behavior, Animal; D003213:Conditioning, Psychological / Q000187:drug effects / Q000502:physiology*; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005239:Fear / Q000502:physiology*; D008297:Male; D010879:Piperazines / Q000494:pharmacology; D051381:Rats; D020318:Rats, Long-Evans; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology*; D013997:Time Factors
D018691:Excitatory Amino Acid Antagonists; D010879:Piperazines; D016194:Receptors, N-Methyl-D-Aspartate; C050592:3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid