Time of conditioning selectively influences contextual fear conditioning: further support for a multiple-memory systems view of fear conditioning.
Time of conditioning influences long-term retention of contextual but not auditory-cue fear conditioning. Long-Evans rats (Rattus norvegicus) conditioned at 12 noon displayed reduced contextual fear conditioning compared to rats conditioned at 8 a.m. or 4 p.m. This effect was eliminated by exposure to the context 24 hr prior to conditioning and by a posttrial injection of corticosterone (1.0 mg/kg). Time of conditioning did not influence short-term retention of contextual fear. These results suggest that time of conditioning influences the posttrial processes that construct a memory representation of the context. They also support the view that contextual and auditory-cue fear conditioning depend on different processes. These results are discussed in relation to the concept of memory storage modulators.
Rudy
J W
JW
Department of Psychology, University of Colorado, Boulder 80309, USA. jrudy@clipr.colorado.edu
Pugh
C R
CR
D000818:Animals; D003213:Conditioning, Psychological; D005239:Fear; D005260:Female; D008297:Male; D008568:Memory / Q000502:physiology*; D051381:Rats; D012153:Retention, Psychology; D013997:Time Factors