Biology subjects

Burgalossi, A.

Publications and source records attributed to Burgalossi, A..

3 recordsLinked to original sources

bioRxiv2026

Hippocampal CA1 neurons are crucial for sleep-associated memory formation in humans: The role of theta power during NREM sleep

The formation of long-term memory during sleep depends on the reactivation and redistribution of recently acquired mnemonic information during non-rapid eye movement (NREM) sleep. Animal studies suggest that hippocampal memory replay during slow-wave sleep is coordinated through the interaction of sharp-wave ripples, thalamocortical sleep spindles, and neocortical slow oscillations (SOs). However, direct evidence for the contribution of hippocampal network dynamics to sleep-dependent memory consolidation in humans remains limited. Here, we investigated sleep-dependent memory consolidation in patients (n=13) with transient global amnesia (TGA), a clinical syndrome associated with focal and transient lesions of the hippocampal CA1 region. Patients completed a verbal paired-associative learning task followed by nocturnal polysomnography and subsequent memory retrieval during the acute phase of TGA (acute condition) and again after clinical recovery (follow-up condition). Overnight memory consolidation was significantly impaired during the acute phase compared with the follow-up session. NREM EEG theta power (4-8 Hz) was reduced during the acute phase of TGA. Importantly, increases in theta power from the acute to the follow-up session predicted corresponding improvements in memory consolidation within individuals. In contrast, established NREM markers of sleep-dependent memory consolidation, including sleep spindle density, SO density, and SO-spindle coupling, did not differ between the acute and follow-up conditions. These findings suggest that transient hippocampal CA1 dysfunction disrupts sleep-related hippocampal network dynamics reflected in reduced NREM theta activity, which in turn is associated with impaired memory consolidation. Sleep-related theta oscillations may therefore represent a functional marker of hippocampal network integrity during sleep-dependent memory consolidation in humans.

neuroscience↗

bioRxiv2026

Post-encoding slow-wave amplitude during a daytime nap predicts pattern completion from sparse visual cues

Pattern completion refers to the reinstatement of a stored memory representation from partial or degraded cues. In this sense, it enables a form of cue-based generalization: the same memory representation can be retrieved across different, incomplete versions of the original input. Sleep supports hippocampus-dependent memory consolidation and may facilitate such flexible retrieval, but it remains unclear whether post-encoding sleep improves visual pattern completion from degraded cues. Previous sleep studies have mainly examined mnemonic discrimination or relational memory, leaving open whether sleep directly enhances the recovery of learned visual scenes from sparse perceptual information. We tested this question using the Memory Image Completion (MIC) task in a polysomnographic within-subject sleep-wake design. Twenty-eight healthy young adults (14 female; mean age 23.4 {+/-} 3.1 years) encoded scene-label associations and were tested immediately and after either a 90-min daytime nap or a matched wake interval. During retrieval, learned and new scenes were presented at five levels of visual completeness. A separate pre-encoding baseline nap assessed individual sleep physiology without prior learning. Sleep did not generally improve performance across all retrieval conditions. Instead, it selectively enhanced consolidation of learned scenes when visual cues were maximally degraded (p = .001) indicating increased pattern completion. No corresponding sleep effect was found for new scenes (all p > .31), suggesting that the benefit was specific to the recovery of previously encoded scene representations. Slow-wave amplitude during the post-encoding nap predicted consolidation of learned scenes under the most degraded condition (p = .011; FDR-corrected p = .042), whereas baseline slow-wave amplitude did not (p > .11). These findings suggest that post-encoding sleep facilitates cue-based recovery of learned visual representations from strongly degraded input, and that this benefit is linked to slow-wave amplitude during post-encoding sleep. Together, these results link sleep-dependent consolidation to visual pattern-completion-like retrieval and extend previous work on sleep-related memory transformation from verbal and relational paradigms to the recovery of learned scene representations from degraded cues.

neuroscience↗

bioRxiv2024

Aversion encoding and behavioral state modulation of lateral habenula neurons

AO_SCPLOWBSTRACTC_SCPLOWThe lateral habenula (LHb) integrates aversive information to regulate motivated behaviors. Despite recent advances in identifying neuronal diversity at the molecular level, in vivo electrophysiological diversity of LHb neurons remains poorly understood. Understanding this diversity is essential for deciphering how information is processed in the LHb. To address this gap, we conducted in vivo electrophysiological recordings in mice and applied unsupervised clustering algorithm to analyze firing patterns. This analysis identified four distinct spontaneous firing patterns of LHb neurons, which were consistent across both anesthetized and awake states. To determine whether these firing patterns correlate with function, we recorded neuronal responses to foot shock stimulation in anesthetized mice and monitored spontaneous behavior in awake mice. We found that low-firing, bursting neurons were preferentially modulated by foot shocks in anesthetized mice and also tracked behavioral states in awake mice. Collectively, our findings indicate significant electrophysiological diversity among LHb neurons, which is associated with their modulation by aversive stimuli and behavioral state.

neuroscience↗