Biology subjects

Buch, E. R.

Publications and source records attributed to Buch, E. R..

7 recordsLinked to original sources

bioRxiv2026

Constricted pupil states index neural replay during wakeful rest in humans

Neural replay has been linked to skill consolidation during wakeful rest, yet its physiological context in humans remains poorly understood. In animals, hippocampal ripples and associated replay occur more frequently within intrinsically oriented brain states associated with constricted pupils, suggesting that pupil dynamics may index neural replay events in humans. We combined magnetoencephalography-derived sequence replay with pupillometry in 25 participants learning a motor sequence across alternating intervals of practice and rest. Replay was indexed by smaller-pupil states, and replay timing clustered on the constricting phase of slow pupil fluctuations. More frequent replay accompanied larger cumulative offline gains during early learning, while smaller rest pupil was associated with better performance when practice resumed. Multivariate pupil features predicted replay-associated states across and within individuals while preceding pupil dynamics showed modest predictive ability to identify the precise onset of individual replay events. Here, we show that constricted-pupil states index neural replay during wakeful rest in humans, linking replay-associated physiology with early motor learning.

neuroscience↗

bioRxiv2026

Expert Motor Synergies Emerge Predominantly Offline During Early Skill Learning

Everyday skilled actions depend on the formation of coordinated motor synergies that integrate multiple digits into stable, low-dimensional control units. Although initial practice of a new skill leads to rapid performance improvements, it is unclear whether the underlying movement kinematics reorganize on a similar timescale and in a way that directly relates to these gains. It also remains uncertain whether such reorganization occurs mainly during active practice or instead during brief rest breaks. Here, we tracked the temporal evolution of multi-digit synergy formation during early learning of a naturalistic keypress skill. Initial practice rapidly sculpted the motor repertoire toward higher-order, temporally compressed and overlapping multi-digit synergies. These synergies emerged after only minutes of practice and continued to be expressed along the full training session. Notably, they were primarily shaped across brief rest breaks and robustly predicted individual skill proficiency. Across learning, distinct synergy subtypes emerged, differing in their heuristic prevalence. Rarely expressed synergies reflected transient novice patterns, synergies expressed at intermediate levels could index exploratory and trial-initiation strategies, and highly expressed synergies emerged later to dominate performance, reflecting the consolidation and expansion of skilled motor control. Together, these findings indicate that skilled performance is supported by the early formation of a compact repertoire of expert multi-digit synergies that emerge preferentially across rest periods and predict subsequent skill gains. They further raise the hypothesis that explicitly training such expert synergies alongside task goals could enhance learning in domains such as the arts, sport, and neurorehabilitation. HighlightsExpert multi-digit synergies form during early skill learning Higher-order synergies emerge across brief rest breaks Fatigue spares expert synergy use during early learning Skill gains mirror multi-digit synergy expression eTOC blurb"Expert multi-digit synergies emerge early in motor learning, strengthen across brief rest breaks, track skill gains, and resist fatigue"

neuroscience↗

bioRxiv2025

Expansion of Working Memory Capacity Supports Early Skill Learning

Motor skill learning depends on refining action sequences through practice, yet how learning unfolds moment-to-moment within trials remains unclear. Here, healthy participants learned generative sequential keypress skills at different speeds. Within trials, we identified reproducible high initial skill (HIS) segments, brief epochs of elevated performance followed by decline, that emerged only during learning of repeating sequences and were absent during practice of pseudo-randomized, non-repeating sequences. HIS keypress content scaled with execution speed and increased with practice. This expansion of HIS segment content continued after overall performance plateaued. Neural analyses showed increased theta-gamma phase-amplitude coupling ({theta}/{gamma} PAC) and beta-band bursts during HIS segments. Hippocampal {theta}/{gamma} PAC predicted HIS content, suggesting a mechanism for binding successive actions into progressively larger skill-memory representations during early learning. Together, these findings identify expansion of skill memory, rather than fatigue, as a key driver of early skill learning.

neuroscience↗

bioRxiv2024

Cingulate and striatal hubs are linked to early skill learning

Early skill learning develops in the context of activity changes in distributed cortico-subcortical regions. Here, we investigated network hubs--centers of information integration and transmission--within the brain network supporting early skill learning. We recorded magnetoencephalographic (MEG) brain activity in healthy human subjects who learned a moderately difficult sequence skill with their non-dominant left hand. We then computed network hub strength by summing top 10% functional connectivity over 86 parcellated brain regions (AAL3 atlas) and five brain oscillatory frequency bands (alpha, low-, high-beta, low- and high-gamma). Virtually all skill gains developed during rest intervals of early learning (micro-offline gains). MEG hub strength in the alpha band (8-13Hz) in bilateral anterior cingulate (ACC) and caudate and in the low-beta band (13-16Hz) in bilateral caudate and right putamen correlated with micro-offline gains. These regions linked strongly with the hippocampus, parahippocampal cortex, and lingual and fusiform gyri. Thus, alpha and low-beta brain oscillatory activity in cingulate and striatal regions appear to contribute as hubs of information integration and transmission during early skill learning. Significance StatementEarly learning of moderately difficult skill sequences develops over periods of rest interspersed with practice (micro-offline gains). We demonstrate here a link between alpha and low-beta oscillatory activity in a cingulate-hippocampo-striato network hubs and rest intervals of early learning.

neuroscience↗

bioRxiv2023

Generalization of procedural motor sequence learning after a single practice trial

When humans begin learning new motor skills, they typically display early rapid performance improvements. It is not well understood how knowledge acquired during this early skill learning period generalizes to new, related skills. Here, we addressed this question by investigating factors influencing generalization of early learning from a skill A to a different, but related skill B. Early skill generalization was tested over four experiments (N = 2,095). Subjects successively learned two related motor sequence skills (skills A and B) over different practice schedules. Skill A and B sequences shared ordinal (i.e. - matching keypress locations), transitional (i.e. - ordered keypress pairs), parsing rule (i.e., distinct sequence events like repeated keypresses that can be used as a breakpoint for segmenting the sequence into smaller units) structures, or possessed no structure similarities. Results showed generalization for shared parsing rule structure between skills A and B after only a single 10-second practice trial of skill A. Manipulating the initial practice exposure to skill A (1 to 12 trials) and inter-practice rest interval (0 to 30s) between skills A and B had no impact on parsing rule structure generalization. Furthermore, this generalization was not explained by stronger sensorimotor mapping between individual keypress actions and their symbolic representations. In contrast, learning from skill A did not generalize to skill B during early learning when the sequences shared only ordinal or transitional structure features. These results document sequence structure that can be very rapidly generalized during initial learning to facilitate generalization of skill.

neuroscience↗

bioRxiv2021

Consolidation of human skill linked to waking hippocampo-neocortical replay

The introduction of rest intervals interspersed with practice strengthens wakeful consolidation of skill. The mechanisms by which the brain binds discrete action representations into consolidated, highly temporally-resolved skill sequences during waking rest are not known. To address this question, we recorded magnetoencephalography (MEG) during acquisition and rapid consolidation of a sequential motor skill. We report the presence of highly prominent, fast waking neural replay during the same rest periods in which rapid consolidation occurs. The observed replay was temporally compressed by approximately 20x relative to the acquired skill, occurred in both forward and reverse directions, was selective for the trained sequence and predicted the magnitude of skill consolidation. Replay representations extended beyond the hippocampus and entrorhinal cortex to the contralateral sensorimotor cortex. These results document the presence of robust hippocampo-neocortical replay supporting rapid wakeful consolidation of skill.

neuroscience↗

bioRxiv2018

Offline coil position denoising enhances detection of TMS effects

OBJECTIVETranscranial magnetic stimulation (TMS) is extensively used in basic and clinical neuroscience. Previous work has shown substantial residual variability in TMS effects even despite use of on-line visual feedback monitoring of coil position. Here, we aimed to evaluate if off-line denoising of variability induced by neuronavigated coil position and orientation deviations can enhance detection of TMS effects.\n\nMETHODSRetrospective modeling was used to denoise the impact of common neuronavigated coil position and rotation deviations during TMS experimental sessions on motor evoked potentials (MEP) to single pulse TMS.\n\nRESULTSNeuronavigated coil deviations explained approximately 44% of total MEP amplitude variability. Offline denoising led to a 136.71% improvement in the signal to noise ratio (SNR) of corticospinal excitability measurements. CONCLUSIONS: Offline modeling enhanced detection of TMS effects by removing variability introduced by neuronavigated coil deviations.\n\nSIGNIFICANCEThis approach could allow more accurate determination of TMS effects in cognitive and interventional neuroscience.\n\nHIGHLIGHTSO_LICoil deviations impact TMS effects despite use of on-line neuronavigation feedback.\nC_LIO_LIOffline denoising of coil deviation impacts on TMS effects significantly reduced variability at trial level.\nC_LIO_LIOffline denoising also significantly improved overall SNR of TMS effects.\nC_LI

neuroscience↗