Does Sleep Improve Your Grammar? : Preferential Consolidation of Arbitrary Components of New Linguistic Knowledge

We examined the role of sleep-related memory consolidation processes in learning new form-meaning mappings. Specifically, we examined a Complementary Learning Systems account, which implies that sleep-related consolidation should be more beneficial for new hippocampally dependent arbitrary mappings (e.g. new vocabulary items) relative to new systematic mappings (e.g. grammatical regularities), which can be better encoded neocortically. The hypothesis was tested using a novel language with an artificial grammatical gender system. Stem-referent mappings implemented arbitrary aspects of the new language, and determiner/suffix+natural gender mappings implemented systematic aspects (e.g. tib scoiffesh + ballerina, tib mofeem + bride; ked jorool + cowboy, ked heefaff + priest). Importantly, the determiner-gender and the suffix-gender mappings varied in complexity and salience, thus providing a range of opportunities to detect beneficial effects of sleep for this type of mapping. Participants were trained on the new language using a word-picture matching task, and were tested after a 2-hour delay which included sleep or wakefulness. Participants in the sleep group outperformed participants in the wake group on tests assessing memory for the arbitrary aspects of the new mappings (individual vocabulary items), whereas we saw no evidence of a sleep benefit in any of the tests assessing memory for the systematic aspects of the new mappings: Participants in both groups extracted the salient determiner-natural gender mapping, but not the more complex suffix-natural gender mapping. The data support the predictions of the complementary systems account and highlight the importance of the arbitrariness/systematicity dimension in the consolidation process for declarative memories

Latency to rapid eye movement sleep as a predictor of treatment response to fluoxetine and placebo in nonpsychotic depressed outpatients

Fluoxetine and placebo were compared in 89 outpatients with major depression with (n = 45) or without (n = 44) a reduced or shortened rapid eye movement latency (SREML) (<=65 minutes) to determine whether rapid eye movement latency (REML) predicted placebo and/or antidepressant response. Men and women were stratified based on polysomnographic recordings and then randomly assigned to receive double-blind fluoxetine (20 mg/day) or placebo for 8 weeks after a 2-week, single-blind, placebo lead-in period. Fluoxetine-treated patients demonstrated a significantly greater reduction in the Hamilton Rating Scale for Depression total score and a significantly greater response rate than placebo-treated patients in both the SREML and the combined strata. Treatment differences in the non-SREML stratum were not statistically significant. Results supported REML as a predictor of placebo nonresponse but did not predict a differential fluoxetine response in patients with SREML compared with patients without SREML.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31545/1/0000468.pd