Motor cortex maps articulatory features of speech sounds

Abstract

The processing of spoken language has been attributed to areas in the superior temporal lobe, where speech stimuli elicit the greatest activation. However, neurobiological and psycholinguistic models have long postulated that knowledge about the articulatory features of individual phonemes has an important role in their perception and in speech comprehension. To probe the possible involvement of specific motor circuits in the speech-perception process, we used event-related functional MRI and presented experimental subjects with spoken syllables, including [p] and [t] sounds, which are produced by movements of the lips or tongue, respectively. Physically similar nonlinguistic signal-correlated noise patterns were used as control stimuli. In localizer experiments, subjects had to silently articulate the same syllables and, in a second task, move their lips or tongue. Speech perception most strongly activated superior temporal cortex. Crucially, however, distinct motor regions in the precentral gyrus sparked by articulatory movements of the lips and tongue were also differentially activated in a somatotopic manner when subjects listened to the lip-or tongue-related phonemes. This sound-related somatotopic activation in precentral gyrus shows that, during speech perception, specific motor circuits are recruited that reflect phonetic distinctive features of the speech sounds encountered, thus providing direct neuroimaging support for specific links between the phonological mechanisms for speech perception and production.cell assembly ͉ functional MRI ͉ perception-action cycle ͉ mirror neurons ͉ phonetic distinctive featue N eurological theories of language have a long-standing tradition of distinguishing specialized modular centers for speech perception and speech production in left superior temporal and inferior frontal lobes, respectively (1-3). Such separate speech-production and -perception modules are consistent with a number of neuroimaging studies, especially the observations that frontal circuits become most strongly active during speech production and that speech input primarily activates the left superior temporal gyrus and sulcus (4-6). Superior temporal speech-perception mechanisms in humans may be situated in areas homologous to the auditory belt and parabelt areas in monkeys (5,7,8). In macaca, this region includes neurons specialized for species-specific calls (9, 10). Therefore, it appeared to be reasonable to postulate a speech-perception module confined to temporal cortex specifically processing acoustic information that is immanent to speech.In contrast to this view, neurobiological models have long claimed that speech perception is connected to production mechanisms (11-16). Similar views have been proposed in psycholinguistics. For example, the direct realist theory of speech perception (17, 18) postulates a link between motor and perceptual representations of speech. According to the motor theory of Liberman et al. (19,20), speech perception requires access to phoneme representations that are c...

Global familiarity of visual stimuli affects repetition-related neural plasticity but not repetition priming

“…Thus, the superior temporal cortex has been shown to be involved in the perception and production of language (Buchsbaum et al, 2001) and object naming (Hirsch, Moreno, & Kim, 2001). Similarly, the area in left inferior precentral gyrus (BA 6), extending into the inferior frontal gyrus (BA 9) has been proposed to be involved in ariculatory processes (Pulvermüller, et al, 2006) and sub-vocalization activity (Dietz, et al, 2005), as well as in certain naming and word-retrieval tasks (Etard, et al, 2000;Grabowski, et al, 1998). Therefore, like the left insula, these regions may be involved in lexical retrieval or covert naming of the F and U objects.…”

Parieto-frontal gamma band activity during the perceptual emergence of speech forms

“…Actually, in past studies, the inferior frontal gyrus has been repeatedly found to be activated during phonological processing, in phoneme monitoring, syllable counting and rhyming tasks (e.g., Démonet et al, 1992Démonet et al, , 1994Paulesu et al, 1993;see Poldrack et al, 1999;Démonet, Thierry and Cardébat, 2005;Vigneau et al, 2006, for a review), as well as during auditory speech perception (e.g., Wilson et al, 2004;Watkins and Paus, 2004;Pulvermuller et al, 2006;Wilson and Iacoboni, 2006). This region thus appears well adapted to syllable parsing process in the present verbal transformation task (Sato et al, 2004), and to speech segmentation in general (Burton and Small, 2006).…”

Interaction between auditory and motor systems in speech perception

“…In addition to the well-known fact that speech production is tightly related to the motor cortex, some studies have shown that the motor cortex is activated in speech perception tasks [24][25][26][27][28][29][30] . For example, when listeners [26,27] , suggesting that different speech stimuli activate motor cortical regions with different patterns.…”

“…For example, when listeners [26,27] , suggesting that different speech stimuli activate motor cortical regions with different patterns. In other words, listening to various verbal stimuli may cause differential automatic activations of cortical regions involved in speech production.…”