Biology subjects

Balasubramaniam, R.

Publications and source records attributed to Balasubramaniam, R..

7 recordsLinked to original sources

bioRxiv2025

The Effect of Musical Groove on Sensorimotor Network Cortical Dynamics during Active Tapping and Passive Listening

Musical groove, defined as the urge to move in response to rhythmic stimuli, drives spontaneous entrainment and engagement with music. Recent studies have investigated the activation of the sensorimotor network (SMN), focusing on the {micro} rhythm, an oscillatory activity in the alpha (8-12 Hz) and beta (16-24 Hz) ranges that reflects motor system engagement. While {micro} modulation differs between passive listening and active movement, it remains unclear whether these responses are shaped by the level of musical groove. Clarifying this relationship is crucial for understanding how neural oscillations transform rhythmic perception into embodied movement and how auditory and motor systems interact to generate the spontaneous urge to move. The present study investigates SMN dynamics by examining {micro} modulation across two factors: mode of engagement - active motor entrainment (finger tapping) versus passive listening, and groove level - low versus high. Electroencephalography (EEG) recordings were used to assess SMN activity, with a focus on {micro} rhythm modulation in the alpha and beta frequency bands. Channel and cluster-based EEG analyses revealed stronger {micro} suppression during active tapping compared to passive listening, as well as an effect of musical groove. Self-reported groove ratings were not affected by the tapping task. Together, these findings highlight the modulation of the {micro} rhythm in the SMN, describing distinctive patterns of neural engagement during the experience of musical groove.

neuroscience↗

bioRxiv2025

The Influence of Force Field Perturbations on Symmetric and Asymmetric Bimanual Reaching

Bimanual symmetric and asymmetric reaching movements require the motor system to coordinate the two limbs under varying spatial and physical demands. While prior research has shown a strong tendency for temporal synchronization between the hands, little is known about how bimanual reaching is organized when each limb is subjected to distinct types of force fields, such as viscous or elastic loads. This study systematically investigated how matched (viscous/viscous, elastic/elastic) and mismatched (e.g., viscous/no load, elastic/no load, viscous/elastic) load conditions influence key timing and kinematic parameters during bimanual reaching tasks across different spatial configurations and force magnitudes. Results show that kinematic measures for each arm, including peak velocity, peak acceleration, and peak deceleration, exhibit significant differences across both matched and mismatched load conditions, reflecting clear adaptations in limb behavior. In contrast, temporal aspects of movement--specifically the timepoints of peak velocity, peak acceleration, peak deceleration, and movement end time--remain coupled under matched loads but become decoupled under mismatched loads, with each limb operating more independently regardless of the spatial configuration of the task. Together, these findings clarify how the motor system balances the need for coordinated bimanual performance with the flexibility required to adapt to varying load conditions. This study extends prior work by demonstrating that not all bimanual reaches are temporally synchronized; instead, task-specific factors such as load type and symmetry critically shape how the limbs coordinate, revealing the motor systems capacity for flexible, context-dependent control.

neuroscience↗

bioRxiv2024

Influence of Cognitive Demand and Auditory Noise on Postural Dynamics

The control of human balance involves an interaction between the human motor, cognitive, and sensory systems. The dynamics of this interaction are yet to be fully understood, however, work has shown the performance of cognitive tasks to have a hampering effect on motor performance, while additive sensory noise to have a beneficial effect. The current study aims to examine whether postural control will be impacted by a concurrent working memory task, and similarly, if additive noise can counteract the expected negative influence of the added cognitive demand. Postural sway of healthy young adults was collected during the performance of a modified N-back task with varying difficulty, in the presence and absence of auditory noise. Our results show a reduction in postural stability scaled to the difficulty of the cognitive task, but this effect is less prominent in the presence of additive noise. Additionally, by separating postural sway into different frequency bands, typically used to assess the exploratory vs feedback-driven stabilizing dynamics of sway, we found a differential effect between the cognitive task and additive noise, thus demonstrating that both frequency regimes of postural sway are sensitive to high cognitive load and increased sensory information.

neuroscience↗

bioRxiv2023

Effects of auditory noise intensity and color on the dynamics of upright stance

Previous work assessing the effect of additive noise on the postural control system has found a positive effect of white noise on postural dynamics. This study covers two separate experiments that were run sequentially to better understand how the structure of the additive noise signal affects postural dynamics, while also furthering our knowledge of how the intensity of auditory stimulation of noise may elicit this phenomenon. Across the two experiments, we introduced three auditory noise stimulations of varying structure (white, pink, and brown noise). Experiment 1 presented the stimuli at 35 dB while Experiment 2 was presented at 75 dB. Our findings demonstrate a decrease in variability of the postural control system regardless of the structure of the noise signal presented, but only for high intensity auditory stimulation.

neuroscience↗

bioRxiv2023

cTBS Over the Left Supplementary Motor Area (lSMA) Does Not Modulate Rhythmic Bimanual Coordination in the Presence and Absence of Visual Cues

Bimanual coordination modes, namely in-phase and anti-phase, represent two distinct movement patterns characterized by simultaneous & symmetrical movements of both hands and alternating complementary actions, respectively. These coordination modes are integral in various activities, such as playing musical instruments, typing, and participating in sports that demand precise hand-eye coordination. The objective of the present experiment was to investigate the impact of continuous theta burst stimulation (cTBS) targeting the left supplementary motor area (lSMA) on bimanual coordination during in/anti-phase coordination modes. To explore this, we utilized a steady-state system of coordination dynamics and evaluated the continuous relative phase ({phi}) and variability of relative phase (SD{phi}) during cued and non-cued trials in both pre- and post-transcranial magnetic stimulation (TMS) conditions. The results revealed that visual cues (cued trials) significantly enhanced bimanual coordination performance in both in/anti-phase coordination modes. However, contrary to expectations, the downregulation of lSMA through cTBS did not lead to significant disruptions in movement during in/anti-phase bimanual coordination in pre- and post-TMS stimulation. Potential factors for the lack of observed effects include methodological limitations, individual differences, and functional redundancy within the motor system. Further research is needed to optimize stimulation parameters, increase sample sizes, and explore the interactions between the lSMA, and other brain regions involved in motor control to gain a comprehensive understanding of the contributions of the lSMA in bimanual coordination.

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bioRxiv2020

Modality-specific frequency band activity during neural entrainment to auditory and visual rhythms

Rhythm perception depends on the ability to predict the onset of rhythmic events. Previous studies indicate beta band modulation is involved in predicting the onset of auditory rhythmic events (Snyder & Large, 2005; Fujioka et al., 2009, 2012). We sought to determine if similar processes are recruited for prediction of visual rhythms by investigating whether beta band activity plays a role in a modality dependent manner for rhythm perception. We looked at source-level EEG time-frequency neural correlates of prediction using an omission paradigm with auditory and visual rhythms. By using omissions, we can separate out predictive timing activity from stimulus driven activity. We hypothesized that there would be modality specific markers of rhythm prediction in induced beta band oscillatory activity, characterized primarily by activation in the motor system specific to auditory rhythm processing. Our findings suggest the existence of overlapping networks of predictive beta activity based on common activation in the parietal and right frontal regions, auditory specific predictive beta in bilateral sensorimotor regions, and visually specific predictive beta in midline central, and bilateral temporal/parietal regions. We also found evidence for evoked predictive beta activity in the left sensorimotor region specific to auditory rhythms. These findings implicate modality dependent networks for auditory and visual rhythm perception. The results further suggest that auditory rhythm perception may have left hemispheric specific mechanisms.

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bioRxiv2018

Multimodal music perception engages motor prediction: a TMS study

Cortico-spinal excitability (CSE) in humans measured with Transcranial Magnetic Stimulation (TMS) is generally increased by the perception of other peoples actions. This perception can be unimodal (visual or auditory) or multimodal (visual and auditory). The increase in TMS-measured CSE is typically prominent for muscles involved in the perceived action (muscle specificity). There are two main classes of accounts for this phenomenon. One suggests that the motor system mirrors the actions that the observer perceives (the resonance account). The other suggests that the motor system predicts the actions that the observer perceives (the predictive account). To test these accounts (which need not be mutually exclusive), subjects were presented with four versions of three-note piano sequences: sound only, sight only, audiovisual, and audiovisual with sound lagging behind while CSE was measured in two hand muscles. Muscle specificity did not interact with modality in the flexor digiti minimi (FDM), but was reliably higher for the first dorsal interosseous (FDI) while subjects perceived the audiovisual version of the three-note piano sequences with sound lagging behind. Since this version of the three-note piano sequences is the only one that overtly violates experience-based expectations, this finding supports predictive coding accounts of motor facilitation during action perception.

neuroscience↗