Molecular, Chronobiological and Behavioural Regulation of Memory and Synaptic Plasticity

Circadian rhythms significantly influence memory, cognition, and synaptic plasticity. The core circadian regulator's CLOCK protein regulates cognitive functions by controlling hippocampal plasticity and memory processes. PERIOD proteins play a principal role in the diurnal regulation of memory consolidation, aligning cognitive performance with the time of day. TIMELESS and BMAL1 synergistically upregulate synaptic plasticity and cognition by regulating gene expression associated with neuronal function. The suprachiasmatic nucleus (SCN), as the master circadian pacemaker, calibrates hippocampal-mediated cognitive processes, synchronizing memory performance with chronobiological activity. Individual chronotypes, dictated by circadian clock genes, display variable influences on brain function involving learning efficacy and retrieval of memory. The hippocampus emerges as a central vertex, linking circadian rhythms with memory via neuroplasticity. The AVLT (Auditory Verbal Learning Test) provides a robust framework to examine circadian effects on human memory performance. Environmental factors such as artificial light at night (ALAN) raise neuronal activity in the ventricular zone, potentially impairing natural circadian cycles. Animal models, particularly mice, manifest that light/dark cycles affect memory formation and synaptic plasticity. Molecular mechanisms supporting circadian cognition comprise BDNF and SIRT1, which underpins neuroplasticity and learning. Proteomic studies identify seven circadian-regulated proteins enriched in processes associated with BDNF and NPAS4, highlighting their roles in memory. Melatonin and MAPK oscillations further improve cognitive outcomes by facilitating chronobiological regulation. These findings emphasize the complex collaboration between circadian rhythms and neuronal mechanisms, providing insights into optimizing cognitive health and therapeutic interventions.