Please join us at the next MCA for a presentation from Dr. Neil Todd
Speaker: Dr. Neil Todd
Title: Effects of stimulus intensity and frequency on the force and timing of sensory-motor synchronisation: Evidence for a vestibular cerebellar contribution?Abstract:
Sensorimotor synchronisation (SMS) in the form of tapping to a regular auditory metronome has been common paradigm to investigate mechanisms of human motor timing (Repp 2005; Repp and Su 2013). Recently there has been an interest in the possible contribution of the vestibular system to timing, with suggestions that it may play an important role in synchronisation, especially given its unique connectivity with the cerebellum (Todd and Lee 2015ab; Todd et al 2016). Here we report the result of an experiment to investigate possible vestibular effects on the kinematics, dynamics and electromyography of finger tapping to a simple anapaest rhythm. In a sample of 10 subjects, index finger acceleration and tapping force were recorded along with extensor/flexor activity and the associated electroencephalographic (EEG) signals measured at central and cerebellar surface electrodes to allow measurement of both evoked and spontaneous activity. In a prior session, using air-conducted sound stimulation with a standard short 2 ms, 500 Hz tone pip, vestibular evoked myogenic potential (VEMP) thresholds were measured and these thresholds were used to set the intensity of the stimuli, at - 3 dB vs + 18 dB relative to the threshold. During the main experiment subjects were asked to synchronise tapping to the pips arranged in the anapaest at two different frequencies, 500 Hz vs 5 kHz, so that only the low-frequency high-intensity condition was a vestibular, as well as an auditory stimulus. We hypothesised that a vestibular effect would manifest in an interaction between the frequency and intensity factors for any dependent measures of tapping performance. The data showed evidence for two distinct timing processes for the flexion and extension stages of a tap cycle and two distinct timing strategies, which we refer to as “staccato” and “legato”, which deploy different use of force and extension. Some evidence was found for vestibular effects in the form of a frequency/intensity interaction, especially for the “legato” timers, but this was likely confounded by an independent intensity effect at both frequencies. Improvements in experimental design in order to increase vestibular effects and reduce confounds will be discussed.
Please join us at 1pm in 3.G.55 or via zoom ID 627 146 998. Link to zoom https://uws.zoom.us/j/627146998
Repp BH (2005) Sensorimotor synchronization: A review of the tapping literature. Psychon. Bull. Rev. 12, 969-992.
Repp BH, Su YH (2013) Sensorimotor synchronization: a review of recent research (2006-2012). Psychon. Bull. Rev. 20, 403-52.
Todd NPM, Lee CS (2015a) The sensory-motor theory of rhythm and beat induction 20 years on: A new synthesis and future perspectives. Front. Hum. Neurosci. 9, 444.
Todd NPM, Lee CS (2015b) Source analysis of electrophysiological correlates of beat induction as sensory-guided action. Front. Psychol. 6, 1178.
Todd NPM , Govender S, Colebatch JG (2016) Vestibular-dependent inter-stimulus interval effects on sound evoked potentials of central origin. Hear. Res. 341, 190-201