Vast Amounts of Encoded Items Nullify but Do Not Reverse the Effect of Sleep on Declarative Memory

Frontiers in Psychology

article

Luca D. Kolibius¹  Jan Born³  Gordon B. Feld³ 

[1] School of Psychology, Cognition and Oscillations Lab, University of Birmingham, United Kingdom;Centre for Human Brain Health, University of Birmingham, United Kingdom;Institute of Medical Psychology and Behavioral Neurobiology, Eberhard Karls University of Tübingen;Centre for Cognitive Neuroimaging, Institute for Neuroscience and Psychology, University of Glasgow, United Kingdom;Werner Reichardt Centre for Integrative Neuroscience, Eberhard Karls University of Tübingen;German Center for Diabetes Research (DZD), Institute for Diabetes Research & Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of Tübingen;Department of Clinical Psychology, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg;Department of Addiction Behavior and Addiction Medicine, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg;Department of Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg

关键词: long-term memory;    sleep;    declarative memory;    consolidation;    interference;    synaptic homeostasis;    forgetting;    sleep deprivation;   

DOI  :  10.3389/fpsyg.2020.607070

学科分类：社会科学、人文和艺术（综合）

来源: Frontiers

【 摘 要 】

Sleep strengthens memories by repeatedly reactivating associated neuron ensembles. Our studies show that although long-term memory for a medium number of word-pairs (160) benefits from sleep, a large number (320) does not. This suggests an upper limit to the amount of information that has access to sleep-dependent declarative memory consolidation, which is possibly linked to the availability of reactivation opportunities. Due to competing processes of global forgetting that are active during sleep, we hypothesized that even larger amounts of information would enhance the proportion of information that is actively forgotten during sleep. In the present study, we aimed to induce such forgetting by challenging the sleeping brain with vast amounts of to be remembered information. For this, 78 participants learned a very large number of 640 word-pairs interspersed with periods of quiet awake rest over the course of an entire day and then either slept or stayed awake during the night. Recall was tested after another night of regular sleep. Results revealed comparable retention rates between the sleep and wake groups. Although this null-effect can be reconciled with the concept of limited capacities available for sleep-dependent consolidation, it contradicts our hypothesis that sleep would increase forgetting compared to the wake group. Additional exploratory analyses relying on equivalence testing and Bayesian statistics reveal that there is evidence against sleep having a detrimental effect on the retention of declarative memory at high information loads. We argue that forgetting occurs in both wake and sleep states through different mechanisms, i.e., through increased interference and through global synaptic downscaling, respectively. Both of these processes might scale similarly with information load.

【 授权许可】

CC BY