Biology subjects

Emerick, M.

Publications and source records attributed to Emerick, M..

2 recordsLinked to original sources

bioRxiv2023

Investigating the Causal Role of Motor Brain Areas in Rhythm Reproduction: A Transcranial Direct Current Stimulation Study

Humans have an intrinsic tendency to move to music. However, our understanding of the neural mechanisms underlying the music-movement connection remains limited, and most studies have used correlational methods. Here, we used transcranial direct current stimulation (tDCS) to investigate the causal role of four brain regions commonly involved in movement timing and beat perception: the supplementary motor area (SMA), left and right premotor cortices (PMC), and the right cerebellum. On three different days, subjects received anodal, cathodal, or sham stimulation while reproducing strong-beat, weak-beat, and non-beat rhythms via finger tapping. Each subject only received stimulation in one of the four brain regions. As the SMA appears to play a primary role in beat perception, while the premotor cortex and cerebellum appear to have a more general role in timing, we predicted that the SMA stimulation would affect reproduction of rhythms with a beat, whereas premotor and cerebellar stimulation would affect reproduction of sequences with no beat. As expected, reproduction accuracy depended on beat strength; strong-beat rhythms were more accurately reproduced than weak and non-beat rhythms. Unexpectedly, tDCS had no effect on reproduction accuracy in any brain region. Thus, we found no evidence that modulating brain excitability in SMA, PMC, or cerebellum altered accuracy of rhythm reproduction. We discuss the implications of these results and future perspectives for this research.

neuroscience↗

bioRxiv2021

Supplementary motor area contributions to rhythm perception

Timing is everything, but our understanding of the neural mechanisms of timing remains limited, particularly for timing of sequences. Temporal sequences can be represented relative to a recurrent beat (beat-based or relative timing), or as a series of absolute durations (non-beat-based or absolute timing). Neuroimaging work suggests involvement of the basal ganglia, supplementary motor area (SMA), the premotor cortices, and the cerebellum in both beat- and non-beat-based timing. Here we examined how beat-based timing and non-beat-based sequence timing were affected by modulating excitability of the supplementary motor area, the right cerebellum, and the bilateral dorsal premotor cortices, using transcranial direct current stimulation (tDCS). Participants were subjected to a sham stimulation session, followed an active stimulation session where anodal or cathodal 2mA tDCS was applied to the SMA, right premotor cortex, left premotor cortex, or the cerebellum. During both sessions, participants discriminated changes in rhythms which differentially engage beat-based or non-beat-based timing. Rhythm discrimination performance was improved by increasing SMA excitability, and impaired by decreasing SMA excitability. This polarity-dependent effect on rhythm discrimination was absent for cerebellar or premotor cortex stimulation, suggesting a crucial role of the SMA and/or its functionally connected networks in rhythmic timing mechanisms.

neuroscience↗