Explaining flexible continuous speech comprehension from individual motor rhythms

Abstract

When speech is too fast, the tracking of the acoustic signal along the auditory pathway deteriorates, leading to suboptimal speech segmentation and decoding of speech information. Thus, speech comprehension is limited by the temporal constraints of the auditory system. Here we ask whether individual differences in auditory-motor coupling strength in part shape these temporal constraints. In two behavioural experiments, we characterize individual differences in the comprehension of naturalistic speech as function of the individual synchronization between the auditory and motor systems and the preferred frequencies of the systems. Obviously, speech comprehension declined at higher speech rates. Importantly, however, both higher auditory-motor synchronization and higher spontaneous speech motor production rates were predictive of better speech-comprehension performance. Furthermore, performance increased with higher working memory capacity (digit span) and higher linguistic, model-based sentence predictability—particularly so at higher speech rates and for individuals with high auditory-motor synchronization. The data provide evidence for a model of speech comprehension in which individual flexibility of not only the motor system but also auditory-motor synchronization may play a modulatory role.

A novel method for estimating properties of attentional oscillators reveals an age-related decline in flexibility

“…This finding is in line with the proposal that perception and production of rhythms are governed by a system of multiple coupled oscillators ( Zalta et al, 2020 ; Assaneo et al, 2021 ), with the observed preferred rate in any task being jointly influenced by preferred rate of a perceptual (in this case, auditory) oscillator, preferred rate of a motor oscillator, and the coupling strength between these two nodes. Indeed, similar discrepancies between preferred rates of auditory and motor oscillators were observed in speech comprehension and were attributed to individual differences in auditory-motor coupling ( Lubinus et al, 2023 ). Under this assumption, we propose that the differences between preferred rate estimates from tasks with and without tapping (motor) responses, i.e., the degree of slowing when the motor component is added, will increase with the difference in eigenfrequencies of the perceptual and motor oscillators (their detuning), and decrease with increasing coupling strength.…”

Region-specific endogenous brain rhythms and their role for speech and language

“…Interestingly, a theta-frequency-specific coupling between auditory and motor cortices has been found that matches the average syllabic rate, which has been termed "intrinsic speech-motor rhythm" ; see also: Barchet et al, o. J.;He et al, 2023). Importantly, behavioral studies have related individual intrinsic motor rhythms in the theta band (quantified by the speaking rate) and individual synchronization tendencies (mapping auditory-motor coupling strength) to speech perception skills (Assaneo et al, 2019(Assaneo et al, , 2021Lubinus et al, 2023; see also : Pfordresher et al, 2021). Notably, the relationship between endogenous motor rhythms and perception has also been behaviorally estimated and computationally modelled in the field of music research (Zamm et al, 2018;Roman et al, 2023).…”

“…Using phase-coupling, it has been shown that the brain engages in different states characterized by frequency-specific connectivity patterns, for example posterior alpha and anterior delta/theta (below 4 Hz and 4-8 Hz, respectively) network activity (Vidaurre et al, 2018). Overall, functional connectivity networks highlight long-range frequency-specific activity during rest, but the varied and diverse rhythmic activity of different brain areas can be more granularly captured by taking a closer look at region-specific patterns of brain activity, as captured for example by spectral profiles (Keitel & Gross, 2016;Mellem et al, 2017;Capilla et al, 2022;Komorowski et al, 2023;Lubinus et al, 2023).…”

Rhythmic temporal prediction enhances neural representations of movement intention for brain–computer interface

“…Strikingly, temporal prediction, especially the rhythmic form, is closely related to the motor system [16][17][18]. For example, in daily life, we often observe enhanced performances in beat-based activities such as singing, playing musical instruments, and perceiving emotional changes in opera when rhythmic motion is involved [17,19,20]. This phenomenon can be explained by the dynamic attending theory [21,22], which suggests that the motor system aligns attentional fluctuations with the timing of task-relevant events.…”