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Consolidation of extinction learning involves transfer from NMDA-independent to NMDA-dependent memory.
- Source :
-
The Journal of neuroscience : the official journal of the Society for Neuroscience [J Neurosci] 2001 Nov 15; Vol. 21 (22), pp. 9009-17. - Publication Year :
- 2001
-
Abstract
- Extinction of conditioned fear to a tone paired with foot shock is thought to involve the formation of new memory. In support of this, previous studies have shown that extinction of conditioned fear depends on NMDA receptor-mediated plasticity. To further investigate the role of NMDA receptors in extinction, we examined the effects of the NMDA antagonist d(-)-3-(2-carboxypiperazine-4-yl)-propyl-1-phosphonic acid (CPP) on the extinction of conditioned freezing and suppression of bar pressing (conditioned emotional response). Rats extinguished normally during a 90 min session in the presence of systemic CPP (10 mg/kg), but were unable to recall extinction learning 24 hr later. This suggests that an NMDA-independent form of plasticity supports short-term extinction memory, but NMDA receptors are required for consolidation processes leading to long-term extinction memory. Surprisingly, extinction learned in the presence of CPP was recalled normally when tested 48 hr after training, suggesting a delayed consolidation process that was able to improve memory in the absence of further training. Delayed consolidation involves NMDA receptors because CPP injected on the rest day between training and test prevented 48 hr recall of extinction learned under CPP. Control experiments showed that the effect of CPP on memory consolidation was not caused by state-dependent learning or reduced expression of freezing under CPP. These findings demonstrate that NMDA receptor activation is critical for consolidation of extinction learning and that this process can be initiated after training has taken place. We suggest that consolidation of extinction involves off-line relearning that reinforces extinction memory through NMDA-mediated plasticity, perhaps in prefrontal-amygdala circuits.
- Subjects :
- Amygdala drug effects
Amygdala physiology
Animals
Behavior, Animal drug effects
Behavior, Animal physiology
Conditioning, Classical drug effects
Conditioning, Classical physiology
Conditioning, Operant drug effects
Conditioning, Operant physiology
Excitatory Amino Acid Antagonists pharmacology
Extinction, Psychological drug effects
Fear physiology
Hippocampus drug effects
Hippocampus physiology
Learning drug effects
Long-Term Potentiation drug effects
Male
Memory drug effects
Mental Recall drug effects
N-Methylaspartate antagonists & inhibitors
Neuronal Plasticity drug effects
Neuronal Plasticity physiology
Piperazines pharmacology
Rats
Rats, Sprague-Dawley
Extinction, Psychological physiology
Learning physiology
Memory physiology
N-Methylaspartate metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1529-2401
- Volume :
- 21
- Issue :
- 22
- Database :
- MEDLINE
- Journal :
- The Journal of neuroscience : the official journal of the Society for Neuroscience
- Publication Type :
- Academic Journal
- Accession number :
- 11698611