Temporal dynamics of sensorimotor integration in speech perception and production: independent component analysis of EEG data

Abstract

Activity in anterior sensorimotor regions is found in speech production and some perception tasks. Yet, how sensorimotor integration supports these functions is unclear due to a lack of data examining the timing of activity from these regions. Beta (~20 Hz) and alpha (~10 Hz) spectral power within the EEG μ rhythm are considered indices of motor and somatosensory activity, respectively. In the current study, perception conditions required discrimination (same/different) of syllables pairs (/ba/ and /da/) in quiet and noisy conditions. Production conditions required covert and overt syllable productions and overt word production. Independent component analysis was performed on EEG data obtained during these conditions to (1) identify clusters of μ components common to all conditions and (2) examine real-time event-related spectral perturbations (ERSP) within alpha and beta bands. 17 and 15 out of 20 participants produced left and right μ-components, respectively, localized to precentral gyri. Discrimination conditions were characterized by significant (pFDR < 0.05) early alpha event-related synchronization (ERS) prior to and during stimulus presentation and later alpha event-related desynchronization (ERD) following stimulus offset. Beta ERD began early and gained strength across time. Differences were found between quiet and noisy discrimination conditions. Both overt syllable and word productions yielded similar alpha/beta ERD that began prior to production and was strongest during muscle activity. Findings during covert production were weaker than during overt production. One explanation for these findings is that μ-beta ERD indexes early predictive coding (e.g., internal modeling) and/or overt and covert attentional/motor processes. μ-alpha ERS may index inhibitory input to the premotor cortex from sensory regions prior to and during discrimination, while μ-alpha ERD may index sensory feedback during speech rehearsal and production.

Is there a common oscillatory brain mechanism for producing and predicting language?

“…Studies of language production have highlighted the relevant role of beta band in forward modeling future sensory information for articulatory monitoring purposes (Jenson et al, 2014). If such Forward Models are similarly recruited for predicting future sensory inputs (Pickering & Garrod, 2007, 2013, we should observe similar oscillatory effects for processing in language scenarios in which active predictive processing is at work that does not involve any motor or monitoring (of motor) activity.…”

“…By measuring EEG, the authors observed relative power modulation in the beta (and also alpha, ~10 Hz) frequency range before picture presentation in left frontal electrodes, i.e., less beta power while participants read high-constraining contexts (preceding the picture) compared to low-constraining ones. Assuming the prediction is production account (Dell & Chang, 2014; see also Pickering & Garrod, 2007), it is possible that the beta modulation reported by Piai and colleagues (2014) does not only reflect stronger motor preparation of the (to be named) target word in the high constraining context, but also the development of a more detailed internal forward model (i.e., an acoustic representation) of that same word (as suggested by Jenson et al, 2014). Klein et al (2014;Wheat, Cornelissen, Frost, & Hansen, 2010) reported MEG beta desynchronization in left inferior frontal regions during the first 100 ms after presentation of a visual target word in a masked priming paradigm.…”

“…These two studies highlight the important role of beta oscillations in language production, showing both power reduction (desynchronization) and increase of cortical connectivity in this frequency band. Jenson et al (2014) required their participants to produce syllables and words both overtly and covertly. In both conditions they observed reduced beta power before production, with weaker effects in covert production.…”

Multisensory and sensorimotor interactions in speech perception

“…By using magnetoencephalography, Alho et al (2014) demonstrate that connectivity between auditory and motor areas increased from passive listening to clear speech to listening to speech in noise, and that the strength of this connectivity was positively correlated with the accuracy of syllable identification. Moreover, analyses of EEG oscillations revealed that alpha and beta rhythms generated in the sensorimotor and auditory areas were modulated during syllable discrimination tasks Jenson et al, 2014). By using theta-burst transcranial magnetic stimulation, Rogers et al (2014) show that disrupting the lip area of the motor cortex impaired discrimination of lip-articulated speech sounds from sounds not articulated on the lips.…”

Mapping the Spatial and Temporal Dynamics of Sensorimotor Integration During the Perception and Performance of Wallowing

“…Additional studies involving the perception of tactile and somatosensory information have reported mu components localized to the sensorimotor and sensory association areas (Gaetz & Cheyne, 2006;Palva et al, 2005;Quandt, Marshall, Bouquet, Shipley, 2013). Based on recent findings from studies of SMI during speech perception and production processes (e.g., Bowers et al, 2013;Jenson et al, 2014), which are known to also elicit cortical sensorimotor activity in the PMC and primary sensorimotor cortices, it therefore seems reasonable to predict that ICA techniques will provide an effective means to identify and localize SMI during the performance of swallowing. Once mu components are identified via ICA, time-frequency analyses can provide measures of sensorimotor activity across time.…”