Biology subjects

Vieweg, P.

Publications and source records attributed to Vieweg, P..

3 recordsLinked to original sources

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↗

bioRxiv2018

The Human Hippocampus Contributes to Egocentric Coding of Distance to a Local Landmark

Spatial navigation can depend on path integration or environmental cues (e.g., landmarks), which are thought to be integrated in hippocampal and entorhinal circuits. This study investigates the anatomical basis of path integration and navigation based on a single local landmark using an individual differences approach, since people vary substantially in their ability to navigate with path integration cues and landmarks. In two experiments, we dissociated the use of path integration and a local landmark in the same navigation task, and investigated whether morphological variability in the hippocampus and entorhinal cortex could explain behavioral variability in young healthy humans. In Experiment 1, participants navigated in a fully immersive virtual reality environment, with body-based cues available for path integration. The participants first walked through a series of posts before attempting to walk back to the remembered location of the first post. We found that gray matter volume of the hippocampus positively predicted behavioral accuracy of retrieving the targets distance in relation to the local landmark. Hippocampus also positively predicted path integration performance in terms of walking-distance to the target location. Experiment 2 was conducted in a desktop virtual environment, with no body-based cues available. Optic flow served as path integration cues, and participants were tested on their memory of a learned target location along a linear track. Consistent with Experiment 1, the results showed that hippocampal volume positively predicted performance on the targets distance in relation to the local landmark. In contrast to Experiment 1, there was no correlation between hippocampal volume and path integration performance. Together, our two experiments provide novel and converging evidence that the hippocampus plays an important role in encoding egocentric distance to a single local landmark during navigation, and they suggest a stronger hippocampal involvement when path integration is based on body-based compared to optic flow cues.

neuroscience↗

bioRxiv2018

Memory Image Completion (MIC): Establishing a task to behaviorally assess pattern completion in humans

For memory retrieval, pattern completion is a crucial process that restores memories from partial or degraded cues. Neurocognitive aging models suggest that the aged memory system is biased toward pattern completion, resulting in a behavioral preference for retrieval over encoding of memories. While there are behavioral tasks to assess the encoding side of these memory differences, pattern completion has received less attention in the literature. Here, we built on our previously developed behavioral recognition memory paradigm - the Memory Image Completion task (MIC) - a task to specifically target pattern completion. First, we used the original design with concurrent eye-tracking in order to rule out perceptual confounds that could interact with recognition performance. Second, we developed parallel versions of the task to accommodate test settings in clinical environments or longitudinal studies. The results show that older adults have a deficit in pattern completion ability with a concurrent bias toward pattern completion - a replication of previously found effects. Importantly, eye-tracking data during encoding could not account for age-related performance differences. At retrieval, spatial viewing patterns for both age groups were more driven by stimulus identity than by response choice, but compared to young adults, older adults fixation patterns overlapped more between stimuli that they (wrongly) thought had the same identity. This supports the observation that when making errors older adults choose responses perceived as similar to the correct stimulus, which is interpreted as a bias toward pattern completion. Additionally, two shorter versions of the task yielded comparable results, and no general learning effects were observed for repeated testing. Together, we present evidence that the MIC is a reliable behavioral task that targets pattern completion, that is easily and repeatedly applicable, and that is made freely available online.

animal behavior and cognition↗