Task-Specific Organization of Activity in Human Jaw Muscles

Moore, Christopher A.; Smith, Anne; Ringel, Robert L.

doi:10.1044/jshr.3104.670

Cited by 96 publications

(151 citation statements)

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“…Our finding that monkeys display a similar perceptual sensitivity to lip-smacking rhythmicity as humans do for speech supports an influential theory by MacNeilage, which suggests that speech evolved through the modification of rhythmic facial movements in ancestral primates (19). In the domain of orofacial motor control, speech movements are faster than chewing movements (54)(55)(56)(57)(58), and an X-ray cineradiography study revealed that, during lip-smacking, the lips, tongue, and hyoid are loosely coordinated as in speech and move with a theta-like rhythm (24). Chewing movements, in comparison, were significantly slower and differently coordinated when compared with lip-smacking (as it is for human chewing versus speech).…”

Section: Discussionsupporting

confidence: 72%

Monkeys are perceptually tuned to facial expressions that exhibit a theta-like speech rhythm

Ghazanfar

Morrill

Kayser

2013

Proc. Natl. Acad. Sci. U.S.A.

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Human speech universally exhibits a 3-to 8-Hz rhythm, corresponding to the rate of syllable production, which is reflected in both the sound envelope and the visual mouth movements. Artificial perturbation of the speech rhythm outside the natural range reduces speech intelligibility, demonstrating a perceptual tuning to this frequency band. One theory posits that the mouth movements at the core of this speech rhythm evolved through modification of ancestral primate facial expressions. Recent evidence shows that one such communicative gesture in macaque monkeys, lip-smacking, has motor parallels with speech in its rhythmicity, its developmental trajectory, and the coordination of vocal tract structures. Whether monkeys also exhibit a perceptual tuning to the natural rhythms of lip-smacking is unknown. To investigate this, we tested rhesus monkeys in a preferential-looking procedure, measuring the time spent looking at each of two side-by-side computer-generated monkey avatars lip-smacking at natural versus sped-up or sloweddown rhythms. Monkeys showed an overall preference for the natural rhythm compared with the perturbed rhythms. This lends behavioral support for the hypothesis that perceptual processes in monkeys are similarly tuned to the natural frequencies of communication signals as they are in humans. Our data provide perceptual evidence for the theory that speech may have evolved from ancestral primate rhythmic facial expressions.

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Section: Discussionsupporting

confidence: 72%

Monkeys are perceptually tuned to facial expressions that exhibit a theta-like speech rhythm

Ghazanfar

Morrill

Kayser

2013

Proc. Natl. Acad. Sci. U.S.A.

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“…Despite large intersubject variability (Ahlgren 1966;Dellow and Lund 1971;Møller 1966), a consistent pattern of muscle activation for chewing has emerged. Most prominent in the chewing cycle is the rigid, reciprocal pattern of alternating activity between antagonist muscles (e.g., anterior digastric with masseter) (Ahlgren 1966;Møller 1966;Moore 1993;Moore et al 1988;Vitti and Basmajian 1977). During the opening phase of mastication the jaw depressors are active, and activity in the jaw elevators is inhibited (Møller 1966;Vitti and Basmajian 1975), yielding a relatively rapid jaw opening phase (Josell et al 1984).…”

Section: Introductionmentioning

confidence: 99%

“…Careful observation reveals characteristic asymmetry in movement paths and wide cycle-to-cycle variations. In fact, the jaw muscles form a complex coordinative network that permits the mandible to meet a variety of task demands posed by chewing, sucking, and speech (Moore et al 1988). Muscles primarily associated with mandibular elevation include the masseter, temporalis, and medial pterygoid (Ahlgren 1966;Luschei and Goldberg 1981;Møller 1966), whereas mandibular depression is associated with activation of the digastric, lateral pterygoid, and suprahyoid group (Luschei and Goldberg 1981;Møller 1966).…”

Section: Introductionmentioning

confidence: 99%

“…A large number of descriptive studies has sought to quantify muscle activation patterns characteristic of chewing by humans (Ahlgren 1966;Alvarado Larrinaga et al 1989;Garrett and Kapur 1986;Horio and Kawamura 1989;Josell et al 1984;Luschei and Goldberg 1981;McCarroll et al 1989;Møller 1966;Moore 1993;Moore et al 1988;Schwartz et al 1984;Steiner et al 1974;Basmajian 1975, 1977). Despite large intersubject variability (Ahlgren 1966;Dellow and Lund 1971;Møller 1966), a consistent pattern of muscle activation for chewing has emerged.…”

Section: Introductionmentioning

confidence: 99%

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Development of Chewing in Children From 12 to 48 Months: Longitudinal Study of EMG Patterns

Green

Moore

Ruark

et al. 1997

Journal of Neurophysiology

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116

106

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Developmental changes in the coordinative organization of masticatory muscles were examined longitudinally in four children over 49 experimental sessions spanning the age range of 12-48 mo. Electromyographic (EMG) records were obtained for right and left masseter muscles, right and left temporalis muscles, and the anterior belly of the digastric. Two independent analytic processes were employed, one that relied on identification of onset and offset of muscle activation and a second that used pairwise cross-correlational techniques. The results of these two analyses, which were found to be consistent with each other, demonstrated that the basic chewing pattern of reciprocally activated antagonistic muscle groups is established by 12 mo of age. Nevertheless, chewing efficiency appears to be improved through a variety of changes in the chewing pattern throughout early development. Coupling of activity among the jaw elevator muscles was shown to strengthen with maturation, and the synchrony of onset and offset of these muscles also increased. Coactivation of antagonistic muscles decreased significantly with development. This decrease in antagonistic coactivation and increase in synchrony among jaw elevators, and a parallel decrease in EMG burst duration, were taken as evidence of increased chewing efficiency. No significant differences in the frequency of chewing were found across the ages studied. Additional considerations include the appropriateness of this coordinative infrastructure for other developing oromotor skills, such as speech production. It is suggested that the relatively fixed coordinative framework for chewing exhibited by these children would not be suitable for adaptation to speech movements, which have been shown to rely on a much more variable and adjustable coordinative organization.

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“…This raises the interesting possibility that subjects may have used higher levels of cocontraction (and hence greater stiffness) to reduce the effect of head acceleration on the jaw during speech. Indeed, there is some empirical evidence that jaw muscle activity during speech is characterized by antagonist coactivation (Moore et al, 1988). Moreover, there is also evidence in studies of single-joint arm movement that increases in muscle coactivation can be used to offset the effects of load (Latash, 1992;Milner and Cloutier, 1993).…”

Section: Discussionmentioning

confidence: 99%