Role of Hippocampal Sleep Spindles in Memory Consolidation

From The Scientist:

Minding the Pulse of Memory Consolidation

Studying sleep spindles could help neuroscientists better understand certain cognitive impairments.

By Richard Kemeny | July 28, 2016

Thalamus (red) WIKIMEDIA, LIFE SCIENCE DATABASES

Sleep is essential for memory. Mounting evidence continues to support the notion that the nocturnal brain replays, stabilizes, reorganizes, and strengthens memories while the body is at rest. Recently, one particular facet of this process has piqued the interest of a growing group of neuroscientists: sleep spindles. For years these brief bursts of brain activity have been largely ignored. Now it seems that examining these neuronal pulses could help researchers better understand—perhaps even treat—cognitive impairments.

Sleep spindles are a defining characteristic of stage 2 non-rapid eye movement (NREM) sleep. These electrical bursts between 10-16 Hz last only around a second, and are known to occur in the human brain thousands of times per night. Generated by a thin net of neurons enveloping the thalamus, spindles appear across several regions of the brain, and are thought to perform various functions, including maintaining sleep in the face of disturbances in the environment.

It appears they are also a fundamental part of the process by which the human brain consolidates memories during sleep.

A memory formed during the day is stored temporarily in the hippocampus, before being spontaneously replayed during the night. Information about the memory is distributed out and integrated into the neocortex through an orchestra of slow-waves, spindles, and rapid hippocampal ripples. Spindles, it seems, could be a guiding force—providing the plasticity and coordination needed for this delicate, interregional transfer of information.

“Spindles appear to play a central role whenever memories during sleep are undergoing transformation that might be necessary to integrate them into neocortical long-term storage networks,” Jan Born, a professor of behavioral neurobiology of the University of Tübingen, told The Scientist during a conference dedicated to sleep spindles held in Budapest in May.

Fewer spindles, therefore, would be expected to coincide with a breakdown in memory consolidation.

Read more.

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