Experimental Brain Research

Desrochers, Phillip C.; Brunfeldt, Alexander T.; Kagerer, Florian A.

doi: 10.1007/s00221-026-07270-5pmid: 41838111

During complex bimanual movements, interference can occur in the form of one hand influencing the action of the contralateral hand. Interference likely results from conflicting sensorimotor information shared between brain regions controlling hand movements via neural crosstalk. However, how visual and force-related feedback processes interact with each other during bimanual reaching is not well understood. In this study, four groups experienced either a visuomotor perturbation, dynamic perturbation, combined visuomotor and dynamic perturbation, or no perturbation in their right hand during bimanual reaches, with each hand controlling its own cursor. The left hand was examined for interference as a consequence of the right-hand perturbation. The results indicated that the visuomotor and combined perturbations showed greater interference in the left hand than the dynamic perturbation. However, the combined perturbation did not show greater interference than the visuomotor perturbation. This suggests that dynamic sensorimotor and visuomotor processes do not interact between hemisphere-hand systems, and that primarily visuomotor processes lead to interference between the hands.

Le, Tri Nghia; Chouinard, Philippe A.; Abou-Sinna, Adam; Sperandio, Irene; Unwin, Katy L.

doi: 10.1007/s00221-026-07246-5pmid: 41733659

The present study investigated the impact of acute technostress (i.e., stress induced by technology – here, computer glitches) and schizotypy on visual illusions, including the Müller-Lyer, Ebbinghaus, Poggendorff, and Ponzo illusions. While previous research has examined perceptual anomalies in schizophrenia and schizotypy, the role of stress in perceptual distortions has been overlooked until recently. In particularly, its acute effects are unknown. Healthy participants completed four visual illusion tasks under two conditions: a standard condition and a technostress-inducing condition involving unpredictable computer glitches. The Galvanic Skin Response (GSR) was recorded as a physiological measure of stress and levels of schizotypy were assessed using the Schizotypal Personality Questionnaire (SPQ). The interpersonal schizotypal subscale was negatively associated with the strength of the Ponzo and Ebbinghaus illusions in both stress conditions while the strength of Poggendorff illusion decreased in both stress conditions with the cognitive-perceptual schizotypy subscale. In addition, a positive relationship emerged between the Müller-Lyer illusion and GSR under the technostress condition. This relationship was not present in the condition without technostress. Conversely, there was a trend for the Poggendorff illusion to increase with GSR in the condition without technostress. This relationship was not present in the condition with technostress. These findings reveal how acute technostress and different components of schizotypy can exert different effects on different illusions, presumably because different mechanisms underlie the different illusions. Our study highlights the relevance of everyday technological stressors for visual perception and underscore the need for future studies to clarify further how stress, schizotypal traits, and perceptual inference are linked mechanistically.

Luo, Yuxuan; Wei, Kunlin

doi: 10.1007/s00221-026-07268-zpmid: 41801402

Motor adaptation arises from multiple learning mechanisms, including use-dependent learning (UDL) driven by repetition and implicit error-based learning (EBL) driven by motor prediction errors. Although both mechanisms contribute implicitly to shaping movement execution, whether these two mechanisms interact remains unclear. The present study used an error-clamp (EC) task to isolate implicit EBL and directly examined whether UDL affects subsequent implicit adaptation. Participants first performed extensive single-target repetitive reaches to induce use-dependent biases and then immediately transitioned to an EC task. We manipulated whether the UDL bias was aligned with, opposed to, or neutral toward the to-be-adapted direction in three separate groups of participants. Results demonstrate that UDL robustly shifted the initial state of adaptation, but did not alter the learning dynamics: all groups showed comparable trial-by-trial adaptation and converged to similar asymptotic levels despite their different initial states. These findings support an independent rather than an interactive relationship between UDL and implicit EBL, highlighting that execution-level motor learning components are additive.

Xie, Liu; Liu, Lian; Wang, Xutao; Wang, Xiao; He, Bolin; Wang, Tiantian; Xu, Honghao; Li, Zhilin; Lei, Shuisheng; Zhu, Xiaoqin

doi: 10.1007/s00221-026-07260-7pmid: 41801405

Epilepsy is a prevalent neurological disorder characterized by recurrent seizures, chronic neuroinflammation, and progressive neurodegeneration. While neuronal hyperexcitability has been extensively studied, the contribution of glial interactions-particularly between astrocytes and microglia-remains poorly understood. Here, we identify the astrocyte–microglia IL-3–IL-3Rα signaling axis as a critical mediator of neuroinflammatory and neurodegenerative responses following status epilepticus (SE). In a pilocarpine-induced SE mouse model, we observed increased expression of interleukin-3 (IL-3) in astrocytes and its receptor IL-3Rα in microglia within the hippocampus. In vitro, IL-3 stimulation induced robust production of pro-inflammatory cytokines (IL-1β, TNF-α, and iNOS) in BV-2 microglia via the JAK2/STAT5 signaling pathway, an effect significantly attenuated by the selective JAK2 inhibitor AG490. In vivo, AG490 treatment reduced seizure severity, suppressed epileptiform EEG discharges, alleviated hippocampal inflammation, and importantly, mitigated SE-induced neuronal loss and nuclear damage in the hippocampus. Collectively, our data demonstrate that the IL-3-IL-3Rα-JAK2/STAT5 signaling axis, while known in other contexts, is a critical mediator of glial communication and pathology in the post-seizure brain, offering a promising target for therapeutic intervention in epilepsy.

Sagehorn, Merle; Johnsdorf, Marike; Kisker, Joanna; Gruber, Thomas; Schöne, Benjamin

doi: 10.1007/s00221-026-07266-1pmid: 41801457

In psychophysiological research on memory encoding and retrieval, Virtual Reality (VR) allows for meaningful insights into mnemonic processing under realistic conditions, yet its effects on working memory (WM) processing and performance remain inconclusive. The present study investigates how information search processes in WM differ when stimulus material is encoded in a conventional monitor-based context or in a more realistic virtual setting, and whether complex, naturalistic stimulus properties facilitate or challenge WM processing and task performance. Participants performed a modified Sternberg task with everyday objects presented either on a 2D monitor or in photorealistic VR. To investigate the search mechanism and WM load, response times, accuracy, and parietal induced alpha activity during retention were analyzed. Across both modalities, response times, error rates, and parietal alpha activity increased with setsize, consistent with serial WM search up to capacity limits. Reaction times were faster for target than non-target probes, suggesting that complex object stimuli engage familiarity- or priming-based components in WM search, particularly in VR. Critically, 3D presentation yielded faster response times across setsizes and lower WM load, reflected by reduced parietal alpha activity during retention, while accuracy was preserved. Moreover, response times in the 2D condition deviated earlier from linearity at higher setsizes, whereas 3D presentation resulted in a more gradual increase, indicating delayed capacity-related saturation. Together, the behavioral and electrophysiological findings indicate that more realistic presentation in VR supports more efficient utilization of WM capacity, likely by facilitating access to stored representations, without altering the fundamental serial nature of WM search.

Hashizoe, Kenya; Nakai, Akio; Nobusako, Satoshi

doi: 10.1007/s00221-026-07265-2pmid: 41843146

Motor imagery (MI) ability has traditionally been assessed using the Hand Laterality Recognition (HLR) task; however, no studies have examined MI ability in children with Developmental Coordination Disorder (DCD) using the Bimanual Coupling (BC) task. This study aimed to clarify MI ability in children with DCD by using both BC and HLR tasks. Fifteen children with DCD and fifteen typically developing (TD) children participated. Motor coordination skills were evaluated using the Movement Assessment Battery for Children-2 (MABC-2), and neurodevelopmental traits were assessed using the ADHD Rating Scale-IV (ADHD-RS-IV) and Social Communication Questionnaire (SCQ).In the BC task, TD children showed a significant increase in the Ovalization Index (OI) in the motor imagery (MI) condition compared to the unimanual (UM) condition, whereas DCD children did not show this increase. Furthermore, the Imagery Coupling Effect (ICE) was significantly lower in the DCD group than in the TD group. In the HLR task, the DCD group demonstrated significantly lower accuracy and efficiency compared to the TD group. Evidence of the biomechanical constraints effect and the hand posture effect was also limited in children with DCD. Additionally, significant correlations were found between ICE and SCQ scores in the BC task, and between HLR accuracy, DCDQ scores, and ADHD traits. These findings suggest that children with DCD experience difficulties in generating MI, regardless of the type of task used for assessment.

Seveso, Martina A.; Hirst, Rebecca J.; O’Dowd, Alan; Camponogara, Ivan; Newell, Fiona N.

doi: 10.1007/s00221-026-07238-5pmid: 41721840

Object categorisation is a fundamental cognitive process, involving the integration of information across the senses. We investigated, using smartphones, whether visual and tactile motion cues could enhance object category learning and generalisation to novel object shapes. Two categories of similar shapes were associated with specific correlated visual and tactile vibration motion cues. After learning object categories, participants were assessed on categorisation of learned and novel objects across four cue conditions: shape-only, shape-visual motion, shape-tactile motion, and shape-visual and tactile motion. We also assessed if accuracy was influenced by blocked versus interleaved cue-conditions at test. In Experiment 1, we found more accurate categorisation and generalisation when all cues were available at test. In Experiment 2 we replicated this effect even when the reliability of the shape-only cue for predicting category membership was reduced. In Experiment 3, we found that the absence of motion cues during learning removed the benefit of motion cues at test. Overall, our findings suggest that multisensory motion cues benefit the formation of novel object categories and allow for better generalisation. The results have implications for our understanding of the underlying dynamic and multisensory nature of object categories and the predictive role of multisensory features on category formation.

Itoh, Yasushi; Akataki, Kumi; Momoi, Chihiro; Inui, Koji; Mita, Katsumi

doi: 10.1007/s00221-026-07249-2pmid: 41721884

Electromyograms (EMGs) of the orbicularis oculi muscle are commonly used to assess the blink reflex, which provides clinically important information. However, mechanomyograms (MMGs) may serve as a promising alternative. This study aimed to evaluate the utility of MMGs in assessing orbicularis oculi responses to stimulation. Electrical stimulation was applied to the facial nerve axons of 25 healthy adult participants, and MMGs were recorded using an accelerometer. The reliability of amplitude-based parameters (Amax and Ap−p) and time-based parameters (Trise, Tzero, Tfall, and Trec) characterizing MMG waveforms was assessed using the intraclass correlation coefficient (ICC), standard error of measurement (SEM), and coefficient of variation (CV). Additionally, the amplitude and temporal characteristics of MMGs evoked by varying stimulus intensities were compared with simultaneously recorded EMGs. All parameters, except Trec, showed high relative reliability (95% confidence interval of ICC of > 0.75) and high absolute reliability (%SEM and CV < 10%). MMG amplitudes (Amax and Ap−p) and EMG amplitudes (Vmax and Vp−p) increased linearly with stimulus intensity. A strong correlation was found between the amplitudes of both signals (Vmax vs. Amax: r = 0.932, p < 0.0001; Vp−p vs. Ap−p: r = 0.937, p < 0.0001). The first positive MMG peak consistently appeared at a fixed interval (5.52 ± 2.10 ms) after the EMG peak, irrespective of stimulus level. These findings suggest that MMG amplitude and latency (stimulus-to-peak time) are reliable indicators of orbicularis oculi muscle activity and can be effectively used alongside EMG in clinical and research settings.Communicated by Bill Yates.

Syrov, Nikolay; Yakovlev, Lev; Berkmush-Antipova, Artemiy; Morozova, Marina; Kaplan, Alexander; Lebedev, Mikhail

doi: 10.1007/s00221-026-07251-8pmid: 41784816

Visual perception enables goal-directed movement control by mapping sensory input onto motor representations. While neural mechanisms of visuomotor integration have been extensively studied, the temporal dynamics of this process during real and mentally simulated movements remain poorly understood, particularly regarding stimulus-driven versus response-driven motor cortex contributions. We used transcranial magnetic stimulation (TMS) and electroencephalography (EEG) to investigate cortical activity during physical and imagined hand movements in a stimulus-response task. Single-pulse TMS was delivered to the primary motor cortex at 100, 200, and 400 ms following visual stimulus presentation to probe corticospinal excitability. Motor cortex facilitation during early preparation was found to be stimulus-locked rather than motor response-locked, indicating that visual cues drive initial motor cortex activation. Both motor execution (ME) and kinesthetic motor imagery (kMI) showed similar facilitation dynamics during this early stage, supporting functional equivalence during preparatory processing. However, ME and kMI diverged at later response stages: ME showed elevated excitability whereas in kMI it returned to baseline. EEG analyses confirmed this dissociation at later stages. Notably, kMI did not produce significant hemispheric lateralization, whereas ME generated robust lateralized readiness potentials whose duration correlated with pre-response motor excitability and behavioral performance. These findings challenge conventional response-driven conceptualizations of motor imagery and highlight stimulus-driven mechanisms in visuomotor processing during both overt and imagined movements.

Wanner, Philipp; Ostermair, Florian; Cristini, Jacopo; Steib, Simon

doi: 10.1007/s00221-026-07256-3pmid: 41801443

A single bout of cardiovascular exercise (CVE) can promote neuroplasticity in an intensity-dependent manner. Consequently, performing CVE immediately after encoding may enhance motor memory consolidation, with stronger effects reported for high intensities. However, most evidence comes from fine-motor tasks, and data on complex whole-body skills are still scarce. In this pre-registered experiment, 41 neurotypical young adults practiced a balance task used to study gross-motor learning. Immediately after encoding, we randomized participants into three groups: a high-intensity interval CVE group (90/60% Wmax), a moderate-intensity interval CVE group (45/25% Wmax), or a resting group. These CVE protocols have previously been shown to enhance consolidation in fine-motor tasks. To evaluate consolidation, we conducted retention tests 24 h and 7 days later and calculated relative offline changes from the end of encoding to the retention tests. Contrary to our hypothesis, both CVE groups showed reduced offline learning at the 24-hour retention test compared to rest (weighted mean CVE: 2.9%; REST: 12.5%), indicating a large effect. This negative effect was unaffected by biological sex, cardiorespiratory fitness, subjective sleep quality, and post-exercise lactate levels, but was no longer present at the 7-day retention test. Our findings suggest that post-encoding CVE may attenuate early consolidation of complex whole-body motor skills, regardless of intensity. This challenges assumptions derived from fine-motor paradigms and holds relevance for applied sport and rehabilitation contexts, warranting further investigation. We discuss possible mechanisms, including catecholamine-driven reduction of frontal brain processes and interference between overlapping neural circuits engaged by the motor task and CVE.