PsyPost reports:

New research provides evidence that the brain’s ability to process signals and adapt to new information fluctuates rhythmically over a 24-hour cycle. A study published in Neuroscience Research reveals that while fatigue appears to suppress immediate neural activity at the end of the active phase, this same period may heighten the brain’s capacity for learning and memory formation. These findings suggest that the brain creates specific temporal windows that are optimized for different types of neural processing.

Biological systems differ significantly from mechanical circuit boards because they do not always produce the same output from the same input. An electrical circuit is hard-wired to respond consistently. A brain, however, operates within a constantly changing internal environment. Factors such as metabolism, hormonal cycles, and sleep pressure shift throughout the day and night.

“Neural circuits do not operate like fixed electronic systems,” explained study authors Yoko Ikoma and Ko Matsui, who are both professors at Tohoku University. “Even when viewing the same scene, what we perceive or remember depends strongly on our internal state at that moment. These fluctuations in responsiveness and metaplasticity are thought to arise from daily shifts in ions and neuromodulatory molecules surrounding neurons.”

“Among the factors shaping this internal environment are physiological rhythms that follow a 24-hour cycle, controlled by the interplay between the circadian clock and the external light–dark cycle. Although these rhythms are known to affect many biological processes, how they influence brain chemistry, neuronal excitability, and plasticity has remained largely unclear.”

“Our study directly examined how time of day alters neural responsiveness in the brains of nocturnal rats. These findings help explain why perception, learning, and fatigue vary across the day in both animals and humans.” [Continue reading…]