The defects of the hippocampal ripples and theta rhythm in depression, and the effects of physical exercise on their amelioration

Koketsu, Shinnosuke; Matsubara, Kazuki; Ueki, Yoshino; Shinohara, Yuta; Inoue, Kōichi; Murakami, Satona; Ueki, Takatoshi

doi:10.1101/2023.01.30.526359

Cited by 1 publication

(1 citation statement)

References 45 publications

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“…63) Moreover, chronic restraint stress depresses the occurrence and magnitude of hippocampal ripples, but this attenuation is rescued by physical exercise in a cage with running wheels. 68) Surprisingly, we demonstrated that short-term preexposure to the novel EE increased the frequency of ripple events in urethane-anesthetized mice, although most hippocampal ripples are likely to be abolished under anesthesia. Chronic exposure of mice to the EE modulates sharp wave-ripple complexes under in vitro conditions, 69) but few studies have explicitly reported an effect of short-term EE-exposure on hippocampal ripples; note that acute EEexposure adds to ripples during subsequent recording in the awake state.…”

Section: Discussionmentioning

confidence: 72%

Short-Term Preexposure to Novel Enriched Environment Augments Hippocampal Ripples in Urethane-Anesthetized Mice

Okada,

Ikegaya,

Matsumoto

2024

Biological & Pharmaceutical Bulletin

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Learning and memory are affected by novel enriched environment, a condition where animals play and interact with a variety of toys and conspecifics. Exposure of animals to the novel enriched environments improves memory by altering neural plasticity during natural sleep, a process called memory consolidation. The hippocampus, a pivotal brain region for learning and memory, generates high-frequency oscillations called ripples during sleep, which is required for memory consolidation. Naturally occurring sleep shares characteristics in common with general anesthesia in terms of extracellular oscillations, guaranteeing anesthetized animals suitable to examine neural activity in a sleep-like state. However, it is poorly understood whether the preexposure of animals to the novel enriched environment modulates neural activity in the hippocampus under subsequent anesthesia. To ask this question, we allowed mice to freely explore the novel enriched environment or their standard environment, anesthetized them, and recorded local field potentials in the hippocampal CA1 area. We then compared the characteristics of hippocampal ripples between the two groups and found that the amplitude of ripples and the number of successive ripples were larger in the novel enriched environment group than in the standard environment group, suggesting that the afferent synaptic input from the CA3 area to the CA1 area was higher when the animals underwent the novel enriched environment. These results underscore the importance of prior experience that surpasses subsequent physical states from the neurophysiological point of view.

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Section: Discussionmentioning

confidence: 72%