Gribble, Paul L., David J. Ostry, Vittorio Sanguineti, and Rafael Laboissière. Are complex control signals required for human arm movement? Neurophysiol. 79: 1409–1424, 1998. It has been proposed that the underlying voluntary movement have a “complex” nonmonotonic time-varying form, number of empirical findings offered in support this idea. In paper, we address three such using model two-joint motion based on λ version equilibrium-point hypothesis. The includes six one- muscles, reflexes,...

In this paper, we address a number of issues in speech research the context equilibrium point hypothesis motor control. The suggests that movements arise from shifts position limb or articulator. is consequence interaction central neural commands, reflex mechanisms, muscle properties, and external loads, but it under control commands. These commands act to shift via centrally specified signals acting at level motoneurone (MN) pool. model sagittal plane jaw hyoid motion based on λ version...

A model of the midsagittal plane motion tongue, jaw, hyoid bone, and larynx is presented, based on λ version equilibrium point hypothesis. The includes muscle properties realistic geometrical arrangement muscles, modeled neural inputs reflexes, dynamics soft tissue bony structures. focus organization control signals underlying vocal tract motions dynamic behavior articulators. number synergies or “basic motions” system are identified. In particular, it shown that systematic sources variation...

In this paper, a multimodal theory accounting for higher order acoustical propagation modes is presented as an extension to the classical plane wave theory. This theoretical development validated against experiments on vocal tract replicas, obtained using 3D printer and finite element simulations. Simplified geometries of increasing complexity are used investigate influence some geometrical parameters properties tract. It shown that can produce additional resonances anti-resonances also...

The effect of normal aging on lexical production and semantic processing was evaluated in 72 healthy participants. Four tasks were used, picture naming (PN), categorization (PC), numerical judgment (NJ), color (CJ). dependence reaction time (RT) correct responses with age accounted by mixed-effects models. Participants underwent neuropsychological testing for verbal, executive, memory functions. RTs increase significantly all tasks. After parceling out the non-specific cognitive decline, as...

This article investigates jaw-finger coordination in a task involving pointing to target while naming it with CVCV (e.g., /papa/) versus word. According the authors' working hypothesis, apex (gesture extremum) would be synchronized of jaw-opening gesture corresponding stressed syllable.Jaw and finger motions were recorded using Optotrak (Northern Digital, Waterloo, Ontario, Canada). The effects stress position on tested across different positions (near vs. far) consonants word (/t/ /p/)....

Humans produce speech by controlling a complex biomechanical apparatus to achieve desired sounds. We show here that kinematic variability in may be influenced patterns of jaw stiffness. A robotic device was used deliver mechanical perturbations the quantify its stiffness mid-sagittal plane. Measured anisotropic. Stiffness greatest along protrusion-retraction axis and least direction raising lowering. Consistent with idea movements reflect directional asymmetries stiffness, during production...

Human adults show an attentional bias towards fearful faces, adaptive behaviour that relies on amygdala function. This emerges in infancy between 5 and 7 months, but the underlying developmental mechanism is unknown. To examine possible precursors, we investigated whether 3.5-, 6- 12-month-old infants facilitated detection of faces noise, compared to happy faces. Happy or mixed with were presented ( N = 192), paired pure noise. We applied multivariate pattern analyses several measures infant...

The radiation of sound from the mouth a speaker is often described using plane piston assumption. This is satisfactory as long wavelength longer than largest transverse dimension vocal tract. For shorter wavelengths, higher order acoustical modes can propagate and particle velocity field in exit plane can be nonuniform. As consequence, assumption does not hold more accurate description of distribution at necessary. achieved multimodal theory which allows one to account for mode...

Motion sickness (MS) usually occurs for a narrow band of frequencies the imposed oscillation. It happens that this frequency is close to which are spontaneously produced by postural sway during natural stance. This study examined relationship between reported susceptibility motion and control. The hypothesis level MS can be inferred from shape Power Spectral Density (PSD) profile spontaneous sway, as measured displacement center mass stationary, upright In Experiment 1, fluctuations while...

The growth of the head and neck its components, including that vocal tract, is not homothetic but appears rather as an anamorphosis. various structures presents a phenomenon heterochrony. Another important issue in tract sexual dimorphism. It was first claimed dimorphism at puberty, recent study has suggested some prepubertal differences exist. To these two phenomena, we used longitudinal radiographic data sixty-eight typical subjects (966 radiographs, taken from 1 month to 25 years) twelve...

Recent studies have demonstrated the ability of subjects to adjust control limb movements counteract effects self-generated loads. The degree which change signals compensate for these loads is a reflection extent forces affecting movement are represented in motion planning. Here, we used empirical and modeling examine whether nervous system compensates acting on jaw during speech production. As walk, vary with direction magnitude head acceleration. We investigated patterns resulting from...

Abstract Ideomotor movements may arise in observers while they watch other people's actions. Previous studies have shown that ideomotor are guided by both perceptual and intentional characteristics of the actions being observed (perceptual induction induction, respectively; cf. Knuf, Aschersleben, & Prinz, 2001; de Maeght 2004). In present study we explore functional basis induction. More specifically raise issue whose intentions count for induction: observers’ own or observees’ (implied)...

Speech production involves some of the most precise and finely timed patterns human movement. Here, in context jaw movement speech, we show that spatial precision speech is systematically associated with regulation impedance particular, stiffness--a measure resistance to displacement. We estimated stiffness also variability during using a robotic device apply brief force pulses jaw. Estimates were obtained perturbed position trajectory an estimate what would be absence load. this "reference...