A local circadian clock for memory?

• Published in: Neuroscience and biobehavioral reviews Vol. 127; pp. 946 - 957
• Main Authors: Lehr, Andrew B., McDonald, Robert J., Thorpe, Christina M., Tetzlaff, Christian, Deibel, Scott H.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 01.08.2021
• Subjects: Circadian rhythms; Hippocampus; Learning and memory; Peripheral oscillator; SCN; Semi-autonomous; Circadian rhythms; Learning and memory; Peripheral oscillator; Semi-autonomous; Hippocampus; SCN; semi-autonomous; hippocampus; peripheral oscillator
• ISSN: 0149-7634; 1873-7528
• DOI: 10.1016/j.neubiorev.2020.11.032

•Exactly how circadian rhythms modulate learning and memory is unclear•Focusing on oscillators in brain areas such as the hippocampus is key•A semi-autonomous oscillator involved in memory was recently discovered•We present a novel framework delineating entrainment of this oscillator•Past and future experiments related to this framework are discussed The master clock, suprachiasmatic nucleus, is believed to control peripheral circadian oscillators throughout the brain and body. However, recent data suggest there is a circadian clock involved in learning and memory, potentially housed in the hippocampus, which is capable of acting independently of the master clock. Curiously, the hippocampal clock appears to be influenced by the master clock and by hippocampal dependent learning, while under certain conditions it may also revert to its endogenous circadian rhythm. Here we propose a mechanism by which the hippocampal clock could locally determine the nature of its entrainment. We introduce a novel theoretical framework, inspired by but extending beyond the hippocampal memory clock, which provides a new perspective on how circadian clocks throughout the brain coordinate their rhythms. Importantly, a local clock for memory would suggest that hippocampal-dependent learning at the same time every day should improve memory, opening up a range of possibilities for non-invasive therapies to alleviate the detrimental effects of circadian rhythm disruption on human health.