Evolution of the speech‐ready brain: The voice/jaw connection in the human motor cortex

Brown, Steven; Yuan, Ye; Belyk, Michel

doi:10.1002/cne.24997

Cited by 32 publications

(33 citation statements)

References 57 publications

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“…A final point of discussion regarding left dPM is the issue of hemispheric laterality. In terms of speech production, it is well established that dLMC is represented bilaterally (Simonyan, 2014), and it has been further suggested that, if anything, activation during phonation is right dominant in the gyral dLMC (Brown et al, 2020). In the present study, significant STRF tuning was observed only in the left dPM.…”

Section: Left Dpm: Encoding Of Vocal Pitch In the Dorsal Laryngeal Motor Cortexsupporting

confidence: 54%

“…Among primates, the dLMC is unique to humans and likely evolved to provide voluntary control of the larynx (Belyk & Brown, 2017;Dichter et al, 2018;Simonyan, 2014). It has been suggested that the dLMC contains sulcal (BA 4) and gyral (BA 6) components (Brown, Yuan, & Belyk, 2020). The seminal study by Brown and colleagues (2008) puts the left-hemisphere peak of the gyral component at MNI coordinate [-54, -2, 46] (see Figure 6, Discussion).…”

Section: Introductionmentioning

confidence: 98%

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Speech-Driven Spectrotemporal Receptive Fields Beyond the Auditory Cortex

Venezia¹,

Richards²,

Hickok³

2021

Preprint

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We recently developed a method to estimate speech-driven spectrotemporal receptive fields (STRFs) using fMRI. The method uses spectrotemporal modulation filtering, a form of acoustic distortion that renders speech sometimes intelligible and sometimes unintelligible. Using this method, we found significant STRF tuning only in classic auditory regions throughout the superior temporal lobes. However, our analysis was not optimized to detect small clusters of tuned STRFs as might be expected in non-auditory regions. Here, we re-analyze our data using a more sensitive multivariate procedure, and we identify STRF tuning in non-auditory regions including the left dorsal premotor cortex (left dPM), left inferior frontal gyrus (LIFG), and bilateral calcarine sulcus (calcS). All three regions responded more to intelligible than unintelligible speech, but left dPM and calcS responded significantly to vocal pitch and demonstrated strong functional connectivity with early auditory regions. However, only left dPM’s STRF predicted activation on trials rated as unintelligible by listeners, a hallmark auditory profile. LIFG, on the other hand, responded almost exclusively to intelligible speech and was functionally connected with classic speech-language regions in the superior temporal sulcus and middle temporal gyrus. LIFG’s STRF was also (weakly) able to predict activation on unintelligible trials, suggesting the presence of a partial ‘acoustic trace’ in the region. We conclude that left dPM is part of the human dorsal laryngeal motor cortex, a region previously shown to be capable of operating in an ‘auditory mode’ to encode vocal pitch. Further, given previous observations that LIFG is involved in syntactic working memory and/or processing of linear order, we conclude that LIFG is part of a higher-order speech circuit that exerts a top-down influence on processing of speech acoustics. Finally, because calcS is modulated by emotion, we speculate that changes in the quality of vocal pitch may have contributed to its response.

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Section: Left Dpm: Encoding Of Vocal Pitch In the Dorsal Laryngeal Motor Cortexsupporting

confidence: 54%

Section: Introductionmentioning

confidence: 98%

Speech-Driven Spectrotemporal Receptive Fields Beyond the Auditory Cortex

Venezia¹,

Richards²,

Hickok³

2021

Preprint

View full text Add to dashboard Cite

show abstract

Section: Introductionmentioning

confidence: 98%

Speech-Driven Spectrotemporal Receptive Fields Beyond the Auditory Cortex

2021

View full text Add to dashboard Cite

We recently developed a method to estimate speech-driven spectrotemporal receptive fields (STRFs) using fMRI. The method uses spectrotemporal modulation filtering, a form of acoustic distortion that renders speech sometimes intelligible and sometimes unintelligible. Using this method, we found significant STRF responses only in classic auditory regions throughout the superior temporal lobes. However, our analysis was not optimized to detect small clusters of STRFs as might be expected in nonauditory regions. Here, we re-analyze our data using a more sensitive multivariate statistical test for crosssubject alignment of STRFs, and we identify STRF responses in non-auditory regions including the left dorsal premotor cortex (dPM), left inferior frontal gyrus (IFG), and bilateral calcarine sulcus (calcS). All three regions responded more to intelligible than unintelligible speech, but left dPM and calcS responded significantly to vocal pitch and demonstrated strong functional connectivity with early auditory regions. Left dPM's STRF generated the best predictions of activation on trials rated as unintelligible by listeners, a hallmark auditory profile. IFG, on the other hand, responded almost exclusively to intelligible speech and was functionally connected with classic speech-language regions in the superior temporal sulcus and middle temporal gyrus. IFG's STRF was also (weakly) able to predict activation on unintelligible trials, suggesting the presence of a partial 'acoustic trace' in the region. We conclude that left dPM is part of the human dorsal laryngeal motor cortex, a region previously shown to be capable of operating in an 'auditory mode' to encode vocal pitch. Further, given previous observations that IFG is involved in syntactic working memory and/or processing of linear order, we conclude that IFG is part of a higherorder speech circuit that exerts a top-down influence on processing of speech acoustics. Finally, because calcS is modulated by emotion, we speculate that changes in the quality of vocal pitch may have contributed to its response.

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“…Both LMC regions were involved during singing as well as whistling, suggesting their functional contribution to voicing and expiration. A different study from the same group tested the somatotopic representation of larynx and jaw muscles, demonstrating again a proximity in both pre-central sites ( Brown et al ., 2020 ), but no functional segregation.…”

Section: Introductionmentioning

confidence: 90%

Two cortical representations of voice control are differentially involved in speech fluency

Neef

Primaßin

Gudenberg

et al. 2021

Brain Communications

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Recent studies have identified two distinct cortical representations of voice control in humans, the ventral and the dorsal laryngeal motor cortex. Strikingly, while persistent developmental stuttering has been linked to a white matter deficit in the ventral laryngeal motor cortex, intensive fluency shaping intervention modulated the functional connectivity of the dorsal laryngeal motor cortical network. Currently, it is unknown whether the underlying structural network organization of these two laryngeal representations is distinct or differently shaped by stuttering intervention. Using probabilistic diffusion tractography in 22 individuals who stutter and participated in a fluency shaping intervention, in 18 individuals who stutter and did not participate in the intervention, and in 28 control participants, we here compare structural networks of the dorsal laryngeal motor cortex and the ventral laryngeal motor cortex and test intervention-related white matter changes. We show (i) that all participants have weaker ventral laryngeal motor cortex connections compared to the dorsal laryngeal motor cortex network, regardless of speech fluency, (ii) connections of the ventral laryngeal motor cortex were stronger in fluent speakers, (iii) the connectivity profile of the ventral laryngeal motor cortex predicted stuttering severity, (iv) but the ventral laryngeal motor cortex network is resistant to a fluency shaping intervention. Our findings substantiate a weaker structural organization of the ventral laryngeal motor cortical network in developmental stuttering and imply that assisted recovery supports neural compensation rather than normalization. Moreover, the resulting dissociation provides evidence for functionally segregated roles of the ventral laryngeal motor cortical and dorsal laryngeal motor cortical networks.

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Evolution of the speech‐ready brain: The voice/jaw connection in the human motor cortex

Cited by 32 publications

References 57 publications

Speech-Driven Spectrotemporal Receptive Fields Beyond the Auditory Cortex

Speech-Driven Spectrotemporal Receptive Fields Beyond the Auditory Cortex

Speech-Driven Spectrotemporal Receptive Fields Beyond the Auditory Cortex

Two cortical representations of voice control are differentially involved in speech fluency

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