Observation-execution matching and action inhibition in human primary motor cortex during viewing of speech-related lip movements or listening to speech

The effect of speech distortion on the excitability of articulatory motor cortex

“…MEPs recorded from M1 hand were not modulated by any dimension of the speech stimuli, in line with previous studies that have shown that speech modulates excitability of the motor representation of the lip specifically (Möttönen and Watkins, 2009;Swaminathan et al, 2013). Our finding of increased motor excitability during perception of distorted relative to natural speech is consistent with predictions made by Wilson & Knoblich (Wilson and Knoblich, 2005), who propose that activity in motor areas is maximal when perception is challenging, and complements and extends previous findings from Murakami and colleagues (Murakami et al, 2011).This contrasts with Pickering and Garrod's (Pickering and Garrod, 2013a) integrated account of perception and production, which postulates that motor activity is greatest when the observer is more familiar with the perceived action (for further detail about simulation accounts and their distinctions, see Pickering and Garrod 2013b).…”

“…In turn, this would suggest that articulator-specific effects would be maximally dissociable in terms of M1-activation when listening is difficult. Indeed, TMS in combination with motor evoked potentials (MEPs) has been found to suggest increased motor processing when perceiving spoken sentences in noise (Murakami et al, 2011), although importantly the effect of speech-internal distortion, and somatotopic responsiveness, are unknown. In addition, it has also been shown that TMS to motor areas can significantly affect accuracy (Meister et al, 2007) , 2012).…”

Listening to speech recruits specific tongue motor synergies as revealed by transcranial magnetic stimulation and tissue-Doppler ultrasound imaging

“…In fact, previous TMS recording of corticobulbar excitability could only show a rather coarse picture of the activation in the motor system [3][4][5][6]26,27]. UTDI, instead, can visualize local tongue motion with great spatial detail.…”

Noninvasive Determination of Speech Dominance by Single Magnetic Stimulation of the Bilateral Hand Motor Cortex

“…13,14,22) Recent studies demonstrated that the specific involvement of hand motor circuits in counting, 1) and observation of speech-related lip movements or listening to speech increases the excitability of the corresponding motor cortex. 16) These studies suggest that speech and the motor cortex have close functional connections. At present, the specific mechanism(s) involved remain unclear, but time course analysis may yield H. Tokimura et al…”