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Changes in brain cartilage may explain why sleep helps you learn

Scientists uncover a potential mechanism behind sleep-induced memory changes

Society for Neuroscience

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IMAGE: A perineuronal net (red) in the mouse brain, surrounding a neuron expressing Arc (green), a protein involved in memory processing. The holes in the perineuronal net may represent sites of... view more 

Credit: Pantazopoulos et al., eNeuro 2020

The morphing structure of the brain's "cartilage cells" may regulate how memories change while you snooze, according to new research in eNeuro.

Sleep lets the body rest, but not the brain. During sleep, the brain accounts for a day of learning by making strong memories stronger and weak memories weaker, a process known as memory consolidation. But changing memories requires changing synapses, the connections between neurons. Sleep-induced changes need to overcome perineuronal nets, cartilage-like sheaths that not only surround and protect neurons, but also prevent changes in synapses.

Pantazopoulos et al. investigated how perineuronal nets varied during sleep in mice. By documenting whether or not they could tag the nets with a protein that binds to a specific sugar chain, they could observe the changes in synapses. A decrease in the number of tagged nets would indicate an increase in the number of neurons allowing synaptic changes.

Tagging increased during wakefulness and decreased during sleep. Sleep deprivation prevented this change. The levels of a net-altering enzyme expressed by brain immune cells cycled in opposition, hinting that it may be responsible for the change. The research team also compared levels of tagged nets in human brain tissue with the donor's time of death. Human brains displayed similar sleep-centric rhythms in net structure. Altering the structure of perineuronal nets may be one of the mechanisms behind sleep-induced memory changes.

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Manuscript title: Circadian Rhythms of Perineuronal Net Composition

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About eNeuro

eNeuro is an online, open-access journal published by the Society for Neuroscience. Established in 2014, eNeuro publishes a wide variety of content, including research articles, short reports, reviews, commentaries and opinions.

About The Society for Neuroscience

The Society for Neuroscience is the world's largest organization of scientists and physicians devoted to understanding the brain and nervous system. The nonprofit organization, founded in 1969, now has nearly 37,000 members in more than 90 countries and over 130 chapters worldwide.

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