Effects of hippocampal lesions in overshadowing and blocking procedures

Peter C. Holland, Gregory D. Fox

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


The effects of ibotenic acid lesions of the hippocampus on overshadowing and blocking were examined in a Pavlovian appetitive conditioning experiment with rats. In a standard test of performance to the overshadowed or blocked target stimulus, sham-lesioned rats displayed both of these stimulus-selection phenomena. Rats with hippocampal lesions showed normal blocking, but no overshadowing. Subsequent inhibitory learning about the target stimulus was slower after overshadowing or blocking procedures than after a control procedure in sham-lesioned rats, but not in lesioned rats. These results suggest that exposure to these procedures can induce hippocampally mediated losses in conditioned stimulus associability (learning rate parameter), even when those losses are not a major determinant of the stimulusselection effects themselves.

Original languageEnglish (US)
Pages (from-to)650-656
Number of pages7
JournalBehavioral Neuroscience
Issue number3
StatePublished - Jun 2003

ASJC Scopus subject areas

  • Behavioral Neuroscience


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