Biology subjects

Oprea, L.

Publications and source records attributed to Oprea, L..

2 recordsLinked to original sources

bioRxiv2026

Closed-Loop Auditory Stimulation Reveals Differential Sleep Oscillatory Contributions to Memory in Healthy Older Adults

Sleep oscillations during non-rapid eye movement (NREM) sleep support memory consolidation but decline with age. Phase-locked auditory stimulation (PLAS) enhances slow-wave activity, yet its effects on distinct oscillatory components and memory in older adults remain unclear. Sixteen healthy older adults (60 years or older; mean age = 65.06 +/- 3.53 years) participated in a randomized, single-blind, sham-controlled crossover study. Participants completed two stimulation nights and two sham nights in a sleep laboratory. Changes in slow oscillations (0.5-1.25 Hz), frontal theta (4-8 Hz), centrofrontal slow spindles (12-14 Hz), and centroparietal fast spindles (14-16 Hz) were compared between stimulation and sham conditions. Declarative memory was assessed using a word-pair recall task that required overnight retention, and broader cognitive performance was evaluated using the Creyos cognitive assessment battery. PLAS enhanced sleep oscillatory activity without altering sleep architecture. Compared with sham, stimulation increased slow oscillation, frontal theta, centrofrontal slow spindle, and centroparietal fast spindle power across both stimulation nights. Although word-pair recall did not improve at the group level, individual differences in stimulation-induced increases in fast spindle power were positively associated with individual differences in overnight memory improvement. Closed-loop auditory stimulation enhances multiple NREM oscillations in healthy older adults while preserving sleep architecture. Moreover, stimulation-induced increases in fast spindle activity track individual differences in overnight memory improvement, suggesting fast spindles as a physiological marker of successful sleep-dependent memory consolidation and a potential target for sleep-based neuromodulation in aging.

neuroscience↗

bioRxiv2022

Characterizing the role of Ca2+ fluxes in defining fast and slow components of spontaneous Ca2+ local transients in OPCs using computational modeling

1Spontaneous Ca2+ local transients (SCaLTs) in isolated oligodendrocyte precursor cells (OPCs) are largely regulated by the following fluxes: store-operated Ca2+ entry (SOCE), Na+/Ca2+ exchange (NCX), Ca2+ pumping through Ca2+-ATPases, and Ca2+-induced Ca2+-release through Ryanodine receptors (RyR) and inositoltriphosphate receptors (IP3R). However, the relative contributions of these fluxes in mediating fast spiking and slow baseline oscillations seen in SCaLTs remain incompletely understood. Here, we developed a stochastic spatiotemporal computational model to simulate SCaLTs in a homogeneous medium with ion flow between the extracellular, cytoplasmic and endoplasmic-reticulum compartments. By simulating the model and plotting both the histograms of SCaLTs obtained experimentally and from the model as well as the standard deviation of interspike intervals (ISI) against ISI averages of multiple model and experimental realizations we revealed that: SCaLTs exhibit very similar characteristics between the two datasets, they are mostly random, they encode information in their frequency, and the slow baseline oscillations could be due to the stochastic slow clustering of IP3R (modeled as an Ornstein-Uhlenbeck noise process). Bifurcation analysis of a deterministic temporal version of the model shows that the contribution of fluxes to SCaLTs depends on the parameter regime and that the combination of excitability, stochasticity, and mixed-mode oscillations are responsible for irregular spiking and doublets in SCaLTs. Additionally, our results demonstrate that blocking each flux reduces SCaLTs frequency and that the reverse (forward) mode of NCX decreases (increases) SCaLTs. Taken together, these results provide a quantitative framework for SCaLT formation in OPCs.

neuroscience↗