Neurobiology of learning and memory
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Neurobiol Learn Mem · Oct 2009
Association learning-dependent increases in acetylcholine release in the rat auditory cortex during auditory classical conditioning.
The cholinergic system has been implicated in sensory cortical plasticity, learning and memory. This experiment determined the relationship between the acquisition of a Pavlovian conditioned approach response (CR) to an auditory conditioned stimulus (CS) and the release of acetylcholine (ACh) in the primary auditory cortex in rats. Samples of ACh were collected via microdialysis during behavioral training in either an auditory classical conditioning task or in a non-associative control task. ⋯ Training was conducted on three consecutive days, with microdialysis samples being collected on Days 1 and 3 in separate sub-groups. The level of ACh released in the auditory cortex during conditioning trials increased from the first to the third day of training in the conditioning group as rats acquired the CR, but did not change in the control group, which did not acquire a CR. These data provide direct evidence for the hypothesis that ACh release increases in the primary auditory cortex during natural memory formation, where cholinergic activation is known to contribute to the formation of specific associative representational plasticity in conjunction with specific memory formation.
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Neurobiol Learn Mem · Oct 2009
Effects of cannabinoids infused into the dorsal hippocampus upon memory formation in 3-days apomorphine-treated rats.
In the present study, the effects of intra-dorsal hippocampus (intra-CA1) injection of cannabinoid receptor agents on memory formation have been investigated in 3-days apomorphine-treated rats. Step-through inhibitory avoidance task of memory has been used to examine retrieval of memory formation, 24h after training. Apomorphine was injected subcutaneously (S. ⋯ The D1 receptor antagonist, SCH 23390 (0.01, 0.02, 0.07 and 0.1 mg/kg/day x 3-days, S. C.), was ineffective in this respect. The results suggest that subchronic apomorphine treatment may induce dopamine D2 receptor sensitization, which in turn prevented amnesia induced by WIN55,212-2.