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Comparison of associative and non‐associative conditioning procedures in the induction of LTD in CA1 of the hippocampus
Author(s) -
Kerr D. Steven,
Abraham Wickliffe C.
Publication year - 1993
Publication title -
synapse
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.809
H-Index - 106
eISSN - 1098-2396
pISSN - 0887-4476
DOI - 10.1002/syn.890140408
Subject(s) - neuroscience , associative property , psychology , dentate gyrus , hippocampus , stimulation , conditioning , hippocampal formation , nmda receptor , associative learning , chemistry , mathematics , biochemistry , statistics , receptor , pure mathematics
Recent reports have indicated that weak activity in a test input, negatively correlated (out‐of‐phase) with tetanization of a separate, converging input, produces an NMDA‐independent, associative long‐term depression (LTD) of the test input synapses, in hippocampal field CA1 (Stanton and Sejnowski, 1989; Stanton et al., 1991). Associative LTD has also been observed in the dentate gyrus, in vivo, but only following “priming” of the test path with 5 Hz stimulation prior to associative conditioning (Christie and Abraham, 1992b). We have used these stimulus protocols, in vitro, in order to compare the induction of non‐associative and associative LTD in field CA1 of the adult rat hippocampus. Stimulation in normal solution evoked a small non‐associative LTD, but no associative LTD. Addition of picrotoxin to the medium facilitated the induction of NMDA‐dependent non‐associative LTD, but not associative LTD. Previously potentiated pathways were not different from naïve pathways in expression of LTD of either kind. Finally, ‘priming’ stimulation (5 Hz) of the test pathway produced a weak, selective enhancement of associative LTD that was, however, not significantly greater than non‐associative LTD. These results indicate that, for our experimental conditions, negatively correlated co‐activity during afferent tetanization does not induce a substantial associative LTD in area CA1. © 1993 Wiley‐Liss, Inc.