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Neuron. 2018 Jan 3;97(1):221-230.e4. doi: 10.1016/j.neuron.2017.11.020. Epub 2017 Dec 14.

Old Brains Come Uncoupled in Sleep: Slow Wave-Spindle Synchrony, Brain Atrophy, and Forgetting.

Author information

1
Helen Wills Neuroscience Institute, UC Berkeley, 132 Barker Hall, Berkeley, CA 94720, USA; Department of Psychology, University of Oslo, Forskningsveien 3A, 0373 Oslo, Norway. Electronic address: rhelfrich@berkeley.edu.
2
Department of Psychiatry and Human Behavior, UC Irvine, 101 The City Dr., Orange, CA 92868, USA; Department of Psychology, UC Berkeley, Tolman Hall, Berkeley, CA 94720, USA.
3
Helen Wills Neuroscience Institute, UC Berkeley, 132 Barker Hall, Berkeley, CA 94720, USA; Department of Psychology, UC Berkeley, Tolman Hall, Berkeley, CA 94720, USA.

Abstract

The coupled interaction between slow-wave oscillations and sleep spindles during non-rapid-eye-movement (NREM) sleep has been proposed to support memory consolidation. However, little evidence in humans supports this theory. Moreover, whether such dynamic coupling is impaired as a consequence of brain aging in later life, contributing to cognitive and memory decline, is unknown. Combining electroencephalography (EEG), structural MRI, and sleep-dependent memory assessment, we addressed these questions in cognitively normal young and older adults. Directional cross-frequency coupling analyses demonstrated that the slow wave governs a precise temporal coordination of sleep spindles, the quality of which predicts overnight memory retention. Moreover, selective atrophy within the medial frontal cortex in older adults predicted a temporal dispersion of this slow wave-spindle coupling, impairing overnight memory consolidation and leading to forgetting. Prefrontal-dependent deficits in the spatiotemporal coordination of NREM sleep oscillations therefore represent one pathway explaining age-related memory decline.

KEYWORDS:

age-related memory decline; aging; atrophy; directional cross-frequency coupling; hierarchical nesting; hippocampus-dependent memory consolidation; overnight forgetting; prefrontal cortex; sleep spindles; slow oscillation

PMID:
29249289
PMCID:
PMC5754239
DOI:
10.1016/j.neuron.2017.11.020
[Indexed for MEDLINE]
Free PMC Article

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