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Edward F. Chang - One of the best experts on this subject based on the ideXlab platform.
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corrigendum functional organization of human sensorimotor cortex for Speech Articulation
2013Co-Authors: Kristofer E Bouchard, Keith A Johnson, Nima Mesgarani, Edward F. ChangAbstract:Nature 495, 327–332 (2013); doi:10.1038/nature11911 In this Article, the referral to the subcentral gyrus as ‘guenon’ was incorrect. As stated, the central sulcus does not terminate at the Sylvian fissure, but instead at the ventral-most U-shaped gyral area1 (as shown in Fig. 1 of the original Article), which should be labelled ‘subcentral gyrus’.
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functional organization of human sensorimotor cortex for Speech Articulation
2013Co-Authors: Kristofer E Bouchard, Keith A Johnson, Nima Mesgarani, Edward F. ChangAbstract:Speaking is one of the most complex actions we perform, yet nearly all of us learn to do it effortlessly. Production of fluent Speech requires the precise, coordinated movement of multiple articulators (e.g., lips, jaw, tongue, larynx) over rapid time scales. Here, we used high-resolution, multi-electrode cortical recordings during the production of consonant-vowel syllables to determine the organization of Speech sensorimotor cortex in humans. We found Speech articulator representations that were somatotopically arranged on ventral pre- and post-central gyri and partially overlapping at individual electrodes. These representations were temporally coordinated as sequences during syllable production. Spatial patterns of cortical activity revealed an emergent, population-level representation, which was organized by phonetic features. Over tens of milliseconds, the spatial patterns transitioned between distinct representations for different consonants and vowels. These results reveal the dynamic organization of Speech sensorimotor cortex during the generation of multi-articulator movements underlying our ability to speak.
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functional organization of human sensorimotor cortex for Speech Articulation
2013Co-Authors: Kristofer E Bouchard, Keith A Johnson, Nima Mesgarani, Edward F. ChangAbstract:Speaking is one of the most complex actions that we perform, but nearly all of us learn to do it effortlessly. Production of fluent Speech requires the precise, coordinated movement of multiple articulators (for example, the lips, jaw, tongue and larynx) over rapid time scales. Here we used high-resolution, multi-electrode cortical recordings during the production of consonant-vowel syllables to determine the organization of Speech sensorimotor cortex in humans. We found Speech-articulator representations that are arranged somatotopically on ventral pre- and post-central gyri, and that partially overlap at individual electrodes. These representations were coordinated temporally as sequences during syllable production. Spatial patterns of cortical activity showed an emergent, population-level representation, which was organized by phonetic features. Over tens of milliseconds, the spatial patterns transitioned between distinct representations for different consonants and vowels. These results reveal the dynamic organization of Speech sensorimotor cortex during the generation of multi-articulator movements that underlies our ability to speak.
Ludo Max - One of the best experts on this subject based on the ideXlab platform.
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feedback delays eliminate auditory motor learning in Speech production
2015Co-Authors: Ludo Max, Derek G MaffettAbstract:Abstract Neurologically healthy individuals use sensory feedback to alter future movements by updating internal models of the effector system and environment. For example, when visual feedback about limb movements or auditory feedback about Speech movements is experimentally perturbed, the planning of subsequent movements is adjusted – i.e., sensorimotor adaptation occurs. A separate line of studies has demonstrated that experimentally delaying the sensory consequences of limb movements causes the sensory input to be attributed to external sources rather than to one’s own actions. Yet similar feedback delays have remarkably little effect on visuo-motor adaptation (although the rate of learning varies, the amount of adaptation is only moderately affected with delays of 100–200 ms, and adaptation still occurs even with a delay as long as 5000 ms). Thus, limb motor learning remains largely intact even in conditions where error assignment favors external factors. Here, we show a fundamentally different result for sensorimotor control of Speech Articulation: auditory-motor adaptation to formant-shifted feedback is completely eliminated with delays of 100 ms or more. Thus, for Speech motor learning, real-time auditory feedback is critical. This novel finding informs theoretical models of human motor control in general and Speech motor control in particular, and it has direct implications for the application of motor learning principles in the habilitation and rehabilitation of individuals with various sensorimotor Speech disorders.
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detecting anticipatory effects in Speech Articulation by means of spectral coefficient analyses
2011Co-Authors: Yongqiang Feng, Grace Hao, Steve An Xue, Ludo MaxAbstract:Few acoustic studies have attempted to examine anticipatory effects in the earliest part of the release of stop consonants. We investigated the ability of spectral coefficients to reveal anticipatory coArticulation in the burst and early aspiration of stops in monosyllables. Twenty American English speakers produced stop (/k,t,p/) - vowel (/ae,i,o/) - stop (/k,t,p/) sequences in two phrase positions. The first four spectral coefficients (mean, standard deviation, skewness, kurtosis) were calculated for one window centered on the burst of the onset consonant and two subsequent, non-overlapping windows. All coefficients showed an influence of vowel-to-consonant anticipatory coArticulation. Which onset consonant showed the strongest vowel effect depended on the specific coefficient under consideration. A context-dependent consonant-to-consonant anticipatory effect was observed for onset /p/. Findings demonstrate that spectral coefficients can reveal subtle anticipatory adjustments as early as the burst of stop consonants. Different results for the four coefficients suggest that comprehensive spectral analyses offer advantages over other approaches. Studies using these techniques may expose previously unobserved articulatory adjustments among phonetic contexts or speaker populations.
Evelina Fedorenko - One of the best experts on this subject based on the ideXlab platform.
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functional characterization of the human Speech Articulation network
2018Co-Authors: Alexandra Basilakos, Evelina Fedorenko, Paul Fillmore, Kimberly G Smith, Julius FridrikssonAbstract:A number of brain regions have been implicated in Articulation, but their precise computations remain debated. Using functional magnetic resonance imaging, we examine the degree of functional specificity of Articulation-responsive brain regions to constrain hypotheses about their contributions to Speech production. We find that Articulation-responsive regions (1) are sensitive to articulatory complexity, but (2) are largely nonoverlapping with nearby domain-general regions that support diverse goal-directed behaviors. Furthermore, premotor Articulation regions show selectivity for Speech production over some related tasks (respiration control), but not others (nonSpeech oral-motor [NSO] movements). This overlap between Speech and nonSpeech movements concords with electrocorticographic evidence that these regions encode articulators and their states, and with patient evidence whereby articulatory deficits are often accompanied by oral-motor deficits. In contrast, the superior temporal regions show strong selectivity for Articulation relative to nonSpeech movements, suggesting that these regions play a specific role in Speech planning/production. Finally, Articulation-responsive portions of posterior inferior frontal gyrus show some selectivity for Articulation, in line with the hypothesis that this region prepares an articulatory code that is passed to the premotor cortex. Taken together, these results inform the architecture of the human Articulation system.
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the superior precentral gyrus of the insula does not appear to be functionally specialized for Articulation
2015Co-Authors: Evelina Fedorenko, Paul Fillmore, Kimberly G Smith, Leonardo Bonilha, Julius FridrikssonAbstract:Broca (Broca P. Bull Soc Anat Paris 36: 330–357, 1861) influentially argued that posterior left inferior frontal gyrus supports Speech Articulation. According to an alternative proposal (e.g., Dron...
Kristofer E Bouchard - One of the best experts on this subject based on the ideXlab platform.
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corrigendum functional organization of human sensorimotor cortex for Speech Articulation
2013Co-Authors: Kristofer E Bouchard, Keith A Johnson, Nima Mesgarani, Edward F. ChangAbstract:Nature 495, 327–332 (2013); doi:10.1038/nature11911 In this Article, the referral to the subcentral gyrus as ‘guenon’ was incorrect. As stated, the central sulcus does not terminate at the Sylvian fissure, but instead at the ventral-most U-shaped gyral area1 (as shown in Fig. 1 of the original Article), which should be labelled ‘subcentral gyrus’.
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functional organization of human sensorimotor cortex for Speech Articulation
2013Co-Authors: Kristofer E Bouchard, Keith A Johnson, Nima Mesgarani, Edward F. ChangAbstract:Speaking is one of the most complex actions we perform, yet nearly all of us learn to do it effortlessly. Production of fluent Speech requires the precise, coordinated movement of multiple articulators (e.g., lips, jaw, tongue, larynx) over rapid time scales. Here, we used high-resolution, multi-electrode cortical recordings during the production of consonant-vowel syllables to determine the organization of Speech sensorimotor cortex in humans. We found Speech articulator representations that were somatotopically arranged on ventral pre- and post-central gyri and partially overlapping at individual electrodes. These representations were temporally coordinated as sequences during syllable production. Spatial patterns of cortical activity revealed an emergent, population-level representation, which was organized by phonetic features. Over tens of milliseconds, the spatial patterns transitioned between distinct representations for different consonants and vowels. These results reveal the dynamic organization of Speech sensorimotor cortex during the generation of multi-articulator movements underlying our ability to speak.
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functional organization of human sensorimotor cortex for Speech Articulation
2013Co-Authors: Kristofer E Bouchard, Keith A Johnson, Nima Mesgarani, Edward F. ChangAbstract:Speaking is one of the most complex actions that we perform, but nearly all of us learn to do it effortlessly. Production of fluent Speech requires the precise, coordinated movement of multiple articulators (for example, the lips, jaw, tongue and larynx) over rapid time scales. Here we used high-resolution, multi-electrode cortical recordings during the production of consonant-vowel syllables to determine the organization of Speech sensorimotor cortex in humans. We found Speech-articulator representations that are arranged somatotopically on ventral pre- and post-central gyri, and that partially overlap at individual electrodes. These representations were coordinated temporally as sequences during syllable production. Spatial patterns of cortical activity showed an emergent, population-level representation, which was organized by phonetic features. Over tens of milliseconds, the spatial patterns transitioned between distinct representations for different consonants and vowels. These results reveal the dynamic organization of Speech sensorimotor cortex during the generation of multi-articulator movements that underlies our ability to speak.
Shrikanth S Narayanan - One of the best experts on this subject based on the ideXlab platform.
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speed accuracy tradeoffs in human Speech production
2018Co-Authors: Adam C Lammert, Shrikanth S Narayanan, Christine H Shadle, Thomas F QuatieriAbstract:Speech motor actions are performed quickly, while simultaneously maintaining a high degree of accuracy. Are speed and accuracy in conflict during Speech production? Speed-accuracy tradeoffs have been shown in many domains of human motor action, but have not been directly examined in the domain of Speech production. The present work seeks evidence for Fitts’ law, a rigorous formulation of this fundamental tradeoff, in Speech Articulation kinematics by analyzing USC-TIMIT, a real-time magnetic resonance imaging data set of Speech production. A theoretical framework for considering Fitts’ law with respect to models of Speech motor control is elucidated. Methodological challenges in seeking relationships consistent with Fitts’ law are addressed, including the operational definitions and measurement of key variables in real-time MRI data. Results suggest the presence of speed-accuracy tradeoffs for certain types of Speech production actions, with wide variability across syllable position, and substantial variability also across subjects. Coda consonant targets immediately following the syllabic nucleus show the strongest evidence of this tradeoff, with correlations as high as 0.72 between speed and accuracy. A discussion is provided concerning the potentially limited applicability of Fitts’ law in the context of Speech production, as well as the theoretical context for interpreting the results.
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on short time estimation of vocal tract length from formant frequencies
2015Co-Authors: Adam C Lammert, Shrikanth S NarayananAbstract:Vocal tract length is highly variable across speakers and determines many aspects of the acoustic Speech signal, making it an essential parameter to consider for explaining behavioral variability. A method for accurate estimation of vocal tract length from formant frequencies would afford normalization of interspeaker variability and facilitate acoustic comparisons across speakers. A framework for considering estimation methods is developed from the basic principles of vocal tract acoustics, and an estimation method is proposed that follows naturally from this framework. The proposed method is evaluated using acoustic characteristics of simulated vocal tracts ranging from 14 to 19 cm in length, as well as real-time magnetic resonance imaging data with synchronous audio from five speakers whose vocal tracts range from 14.5 to 18.0 cm in length. Evaluations show improvements in accuracy over previously proposed methods, with 0.631 and 1.277 cm root mean square error on simulated and human Speech data, respectively. Empirical results show that the effectiveness of the proposed method is based on emphasizing higher formant frequencies, which seem less affected by Speech Articulation. Theoretical predictions of formant sensitivity reinforce this empirical finding. Moreover, theoretical insights are explained regarding the reason for differences in formant sensitivity.
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motor control primitives arising from a learned dynamical systems model of Speech Articulation
2014Co-Authors: Vikram Ramanarayanan, Louis Goldstein, Shrikanth S NarayananAbstract:We present a method to derive a small number of Speech motor control “primitives” that can produce linguisticallyinterpretable articulatory movements. We envision that such a dictionary of primitives can be useful for Speech motor control, particularly in finding a low-dimensional subspace for such control. First, we use the iterative Linear Quadratic Gaussian with Learned Dynamics (iLQG-LD) algorithm to derive (for a set of utterances) a set of stochastically optimal control inputs to a learned dynamical systems model of the vocal tract that produces desired movement sequences. Second, we use a convolutive Nonnegative Matrix Factorization with sparseness constraints (cNMFsc) algorithm to find a small dictionary of control input primitives that can be used to reproduce the aforementioned optimal control inputs that produce the observed articulatory movements. The method performs favorably on both qualitative and quantitative evaluations conducted on synthetic data produced by an articulatory synthesizer. Such a primitivesbased framework could help inform theories of Speech motor control and coordination. Index Terms: Speech motor control, motor primitives, synergies, dynamical systems, iLQG, NMF.
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a study of emotional Speech Articulation using a fast magnetic resonance imaging technique
2006Co-Authors: Sungbok Lee, Erik Bresch, Jason Adams, Abe Kazemzadeh, Shrikanth S NarayananAbstract:A recently developed fast MR imaging system is utilized for a study of emotional Speech production. Speech utterances and corresponding mid-sagittal vocal tract images are simultaneously acquired by the MRI system. Neutral, angry, sad and happy emotions are simulated by a male American English speaker. The MRI system and analysis results are described in this report. In general Articulation is found to be more active in terms of the rate of vocal tract shaping and the ranges of spectral parameter values in emotional Speech. It is confirmed that angry Speech is characterized by wider and faster vocal tract shaping. Moreover, angry Speech shows the more prominent usage of the pharyngeal region than any other emotions. It is also observed that the average vocal tract length above the false vocal folds varies as a function of emotion and that happy Speech exhibit relatively shorter length than other emotions. It is likely that this is due to the elevation of the larynx and that may facilitate the higher pitch and larger pitch range manipulation to encode happy emotional quality by the speaker.
