Differential effects of ibotenic acid lesions of the hippocampus and blockade of N-methyl-D-aspartate receptor-dependent long-term potentiation on contextual processing in rats.
The contextual specificity of appetitive conditioned responding was examined in rats undergoing chronic intracerebroventricular infusion of 15 or 30 mM D-2-amino-5-phosphonopentanoic acid (D-AP5) or with excitotoxic hippocampal lesions. The magnitude of conditioned responding by control rats and rats infused with D-AP5 to a conditioned stimulus (CS) trained in Context A was attenuated when the same stimulus was presented in Context B. By contrast, hippocampal-lesioned rats displayed comparable levels of responding to the CS when presented in either Context A or B. Subsequent in vivo electrophysiological investigations showed that the D-AP5 concentrations were effective in blocking long-term potentiation (LTP) in the dentate gyrus. Results indicate that rats are capable of processing contextual information in the absence of N-methyl-D-aspartate (NMDA) receptor-dependent LTP and demonstrate an important dissociation between the effects of hippocampal lesions and the blockade of NMDA receptors in the hippocampus.
Good
M
M
Centre for Neuroscience, University of Edinburgh, Scotland.
Bannerman
D
D
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology*; D000818:Animals; D001070:Appetitive Behavior / Q000187:drug effects / Q000502:physiology; D003213:Conditioning, Psychological / Q000187:drug effects* / Q000502:physiology; D003463:Cues; D004193:Discrimination Learning / Q000187:drug effects* / Q000502:physiology; D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D019706:Excitatory Postsynaptic Potentials; D006624:Hippocampus / Q000187:drug effects* / Q000473:pathology / Q000503:physiopathology; D007051:Ibotenic Acid; D015918:Infusion Pumps, Implantable; D017774:Long-Term Potentiation / Q000187:drug effects* / Q000502:physiology; D008297:Male; D008568:Memory / Q000187:drug effects / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects* / Q000502:physiology; D013238:Stereotaxic Techniques
D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; D007051:Ibotenic Acid; D015763:2-Amino-5-phosphonovalerate