The hearing ear is always found close to the speaking tongue : Review of the role of the motor system in speech perception

Abstract

Does "the motor system" play "a role" in speech perception? If so, where, how, and when? We conducted a systematic review that addresses these questions using both qualitative and quantitative methods. The qualitative review of behavioural, computational modelling, non-human animal, brain damage/disorder, electrical stimulation/recording, and neuroimaging research suggests that distributed brain regions involved in producing speech play specific, dynamic, and contextually determined roles in speech perception. The quantitative review employed region and network based neuroimaging meta-analyses and a novel text mining method to describe relative contributions of nodes in distributed brain networks. Supporting the qualitative review, results show a specific functional correspondence between regions involved in non-linguistic movement of the articulators, covertly and overtly producing speech, and the perception of both nonword and word sounds. This distributed set of cortical and subcortical speech production regions are ubiquitously active and form multiple networks whose topologies dynamically change with listening context. Results are inconsistent with motor and acoustic only models of speech perception and classical and contemporary dual-stream models of the organization of language and the brain. Instead, results are more consistent with complex network models in which multiple speech production related networks and subnetworks dynamically self-organize to constrain interpretation of indeterminant acoustic patterns as listening context requires.

Neurocomputational Consequences of Evolutionary Connectivity Changes in Perisylvian Language Cortex

“…Short sensorimotor path length may offer a mechanism not only for verbal working memory, but also for the coupling of auditory and motor information related to speech (for a related computational model, see Westermann and Miranda, 2004). This coupling could also explain why auditory-articulatory interactions are pervasive in speech perception and comprehension (Schomers and Pulvermüller, 2016; Skipper et al, 2017). …”

Language Control and Code-switching

“…In Figure 1, the lower right quarter of the figure indicates that speech production processes can tacitly support speech perception (Halle and Stevens 1962;Skipper et al 2017). The upper right quadrant refers to processes that can determine the meaning of what is said and induce significance.…”

Brain reorganization in anticipation of predictable words

“…The intersection of contrasts 1) and 2) showed activity in sensorimotor regions typically thought to be involved in speech perception and production 22 . These include bilateral posterior superior temporal cortices, inferior parietal lobule (IPL), the pars opercularis (POp; 'Broca's area'), supplementary motor area (SMA), pre-and primary motor cortices and the cerebellum (Figure 3 left column and white outline; Table S1).…”

“…If different patterns of activity are associated with different contexts, and contexts are always changing during real-world language use, it implies that the organization of language and the brain is much less static and more dynamic than existing models can accommodate. Indeed, studies of the network organization supporting resting states, auditory tone processing and natural language all suggest that language and the brain is dynamic and distributed throughout the brain 22,32,[41][42][43] . These studies and our results thus suggest that more research pertaining to how the brain uses context is needed in order to build a more complete and accurate model of the neurobiology of language 12 .…”

“…Furthermore, speech production associated networks seem to play ubiquitous roles in speech perception 22 and more predictable speech results in a decrease in AC activity compared to less predictable speech 11 . However, inferences about the role of prediction in the neurobiology of speech perception have been based entirely on differences between responses to more versus less predictable words once they have been presented.…”