Interactions of time of day and sleep with between-session habituation and extinction memory in young adult males

摘要

Within-session habituation and extinction learning co-occur as do subsequent consolidation of habituation (i.e., between-session habituation) and extinction memory. We sought to determine if, as we predicted: (1) between-session habituation is greater across a night of sleep vs. a day awake; (2) time-of-day accounts for differences; (3) between-session habituation predicts consolidation of extinction memory; (4) sleep predicts between-session habituation and/or extinction memory. Participants (N=28) completed 4–5 sessions alternating between mornings and evenings over 3 successive days (2 nights) with session 1 in either the morning (N=13) or evening (N=15). Twelve participants underwent laboratory polysomnography. During 4 sessions, participants completed a loud-tone habituation protocol while skin-conductance response (SCR), blink-startle electromyography (EMG), heart-rate acceleration (HRA) and deceleration (HRD) were recorded. For sessions 1 and 2, between-session habituation of EMG, SCR and HRD was greater across sleep. SCR and HRD were generally lower in the morning. Between-session habituation of SCR for sessions 1 and 2 was positively related to intervening (first night) slow wave sleep. In the evening before night 2, participants also underwent fear conditioning and extinction learning phases of a second protocol. Extinction recall was tested the following morning. Extinction recall was predicted only by between-session habituation of SCR across the same night (second night) and by intervening REM. We conclude that: 1) sleep augments between-session habituation, as does morning testing; 2) extinction recall is predicted by concurrent between-session habituation; and 3) both phenomena may be influenced by sleep.