title: Dopamine dependent setting of a circadian oscillator underlying the memory for time of day.
abstract: Animals learn and remember the time of day that significant conditions occur, and anticipate recurrence at 24-h intervals, even after only one exposure to the condition. On several place-conditioning tasks, animals show context avoidance or preference only near the time of day of the experience. The memory for time of day is registered by a circadian oscillator that is set at the time of the training. We show that manipulations of dopamine (DA) neurotransmission can set a time memory in place preference and avoidance tasks, indicating that time of day is part of the context that is learned. Single injections of the DA agonist, d-amphetamine sulfate given without further exposure to the conditioning apparatus, can reset the timing of anticipatory behavior evoked by previously acquired place-event associations. The data support a model for time memory in which DA signaling sets the phase of a circadian oscillator, which returns to the same state at regular 24-h intervals. The data also raise the possibility that some apparent impairments of memory formation or retention could reflect post-experience resetting of the optimal retrieval time rather than impairment of memory or retrieval per se.
authors.affiliation: Centre for Biological Timing and Cognition, Department of Psychology, University of Toronto, 100 St. George Street, Toronto, Ontario M5S 3G3, Canada.
authors.forename: Sean W
authors.initials: SW
authors.lastname: Cain
authors.affiliation: Centre for Biological Timing and Cognition, Department of Psychology, University of Toronto, 100 St. George Street, Toronto, Ontario M5S 3G3, Canada.
authors.forename: Omar A
authors.initials: OA
authors.lastname: Rawashdeh
authors.affiliation: Centre for Biological Timing and Cognition, Department of Psychology, University of Toronto, 100 St. George Street, Toronto, Ontario M5S 3G3, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Siu
authors.affiliation: Centre for Biological Timing and Cognition, Department of Psychology, University of Toronto, 100 St. George Street, Toronto, Ontario M5S 3G3, Canada.
authors.forename: Seung Cheol
authors.initials: SC
authors.lastname: Kim
authors.affiliation: Centre for Biological Timing and Cognition, Department of Psychology, University of Toronto, 100 St. George Street, Toronto, Ontario M5S 3G3, Canada. Electronic address: ralph@psych.utoronto.ca.
authors.forename: Martin R
authors.initials: MR
authors.lastname: Ralph
mesh_terms: D000818:Animals; D001683:Biological Clocks / Q000187:drug effects*; D002940:Circadian Rhythm / Q000187:drug effects*; D003216:Conditioning, Operant / Q000187:drug effects; D003913:Dextroamphetamine / Q000494:pharmacology*; D018492:Dopamine Antagonists / Q000494:pharmacology*; D018765:Dopamine Uptake Inhibitors / Q000494:pharmacology*; D006220:Haloperidol / Q000494:pharmacology*; D008297:Male; D008568:Memory / Q000187:drug effects*; D008647:Mesocricetus; D013998:Time Perception / Q000187:drug effects
chemical_list: D018492:Dopamine Antagonists; D018765:Dopamine Uptake Inhibitors; D006220:Haloperidol; D003913:Dextroamphetamine
keywords: Amphetamine; Circadian rhythms; DA; Haloperidol; Memory; Place preference; Time-of-day learning