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Predicting masticatory jaw movements from chin movements using multivariate linear methods.

Previously, we have used bivariate correlations of maximum and minimum displacement, velocity and acceleration variables to compare masticatory chin and jaw movements (J. Prosthet. Dent. 81 (1999) 179). This previous study represented a first step in exploring the hypothesis that the chin contained useful information regarding jaw kinematics. The current study extends our understanding of the relationship between masticatory chin and jaw movements by: (1) reconstructing and evaluating a more continuous trajectory of chin and jaw movements, and (2) performing multivariate correlations comparing chin and jaw movements at discrete points along the trajectory in order to gain insight into the coupling of chin and jaw movements during a chewing cycle. Results indicated that chin and jaw movement trajectories were visually similar in the lateral, vertical, and anteroposterior axes. The adjusted R(2) results in the lateral, vertical, and anteroposterior dimensions averaged 0.74, 0.78, and 0.89, respectively. Within chewing cycles, the lowest correlations between chin and jaw movements in the lateral and vertical dimensions occurred when the jaw was relatively closed, whereas the lowest correlations between chin and jaw movements in the anteroposterior dimension occurred while the jaw was opening from a closed position. The results indicated that jaw and chin movements were qualitatively similar and that at least 74% of the variation in jaw movements could be accounted for by multivariate linear models of chin movement.

Adult↗

Proprioceptive population coding of two-dimensional limb movements in humans: I. Muscle spindle feedback during spatially oriented movements.

The proprioceptive coding of multidirectional ankle joint movements was investigated, focusing in particular on the question as to how accurately the direction of a movement is encoded when all the proprioceptive information from all the muscles involved in the actual movement is taken into account. During ankle movements imposed on human subjects, the activity of 30 muscle spindle afferents originating in the extensor digitorum longus, tibialis anterior, extensor hallucis longus and peroneus lateralis muscles was recorded from the lateral peroneal nerve using the microneurographic technique. In the first part of the study, it was proposed to investigate whether muscle spindle afferents have a preferred direction, as previously found to occur in the case of cortical cells, and to analyze the neural coding of the movement trajectories using a "population vector model." This model is based on the idea that neuronal coding can be analyzed in terms of a series of vectors, each based on specific movement parameters. In the present case, each vector gives the mean contribution of a population of muscle spindle afferents within one directionally tuned muscle. A given population vector points in the "preferred sensory direction" of the muscle to which it corresponds, and its length is the mean frequency of all the afferents within that muscle. Our working hypothesis was that the sum of these weighted vectors points in the same direction as the ongoing movement. The results show that each muscle spindle afferent, and likewise each muscle, has a specific preferred sensory direction, as well as a preferred sensory sector within which it is capable of sending sensory information to the central nervous system. Interestingly, the results also demonstrate that the preferred directions are the same as the directions of vibration-induced illusions. In addition, the results show that the neuronal population vector model describes the multipopulation proprioceptive coding of spatially oriented 2D limb movements, even at the peripheral sensory level, based on the sum vectors calculated from all the muscles involved in the movement. In an accompanying paper, the coding of more complex 2D movements such as those involved in drawing rectilinear and curvilinear geometrical shapes was investigated.

Adult↗

Relationship between cocontraction, movement kinematics and phasic muscle activity in single-joint arm movement.

Patterns of muscle coactivation provide a window into mechanisms of limb stabilization. In the present paper we have examined muscle coactivation in single-joint elbow and single-joint shoulder movements and explored its relationship to movement velocity and amplitude, as well as phasic muscle activation patterns. Movements were produced at several speeds and different amplitudes, and muscle activity and movement kinematics were recorded. Tonic levels of electromyographic (EMG) activity following movement provided a measure of muscle cocontraction. It was found that coactivation following movement increased with maximum joint velocity at each of two amplitudes. Phasic EMG activity in agonist and antagonist muscles showed a similar correlation that was observable even during the first 30 ms of muscle activation. All subjects but one showed statistically significant correlations on a trial-by-trial basis between tonic and phasic activity levels, including the phasic activity measure taken at the initiation of movement. Our findings provide direct evidence that muscle coactivation varies with movement velocity. The data also suggest that cocontraction is linked in a simple manner to phasic muscle activity. The similarity in the patterns of tonic and phasic activation suggests that the nervous system may use a simple strategy to adjust coactivation and presumably limb impedance in association with changes in movement speed. Moreover, since the pattern of tonic activity varies with the first 30 ms of phasic activity, the control of cocontraction may be established prior to movement onset.

Adult↗

[Diagnosis of supranuclear eye movement disorders. Part I: different types of eye movements].

The hallmark of a supranuclear eye movement disorder is a functional impairment of one or several types of different eye movements while other types of eye movements still work. All eye movement information is conveyed via the nuclei of the eye muscle nerves. However, the information for a specific type of eye movement is generated in prenuclear cortical and subcortical areas which are activated depending on the type of eye movement performed. Knowledge about the anatomy of these areas enables us to make a clinical diagnosis or to localize the pathological process to a specific area in many neurological conditions. Examination of eye movements are thus a valuable clinical tool in many neurological and neuroophthalmological diseases. The first part of this two-part contribution presents the different types of eye movements, the concept of neural integration, and prenuclear structures important for horizontal eye movement as well as the pertinent pathology. The second part will appear in the next issue and deals with the cerebral structures that are relevant for vertical eye movements including their pathology.

Diagnosis, Differential↗

Effects of movement direction upon kinematic characteristics of vertical arm pointing movements in man.

Vertical arm pointing movements in two directions (upwards and downwards), imposing two different loads (unload and 0.5 kg) and speeds (normal and fast) have been studied in six subjects. Movements were recorded using an optoelectronic system. Data analysis concentrated upon finger-tip kinematics. Significant effects of movement direction were recorded upon velocity profiles. The acceleration time, computed relative to total movement time, was greater for downward movements than for upward movements. In contrast however, no effects of load or speed were observed. Movement time was not affected by movement direction or load, for both speeds tested. These results suggest different planning processes, for movements with and against gravity and indicate that gravitational force influences the processes controlling movement execution.

Acceleration↗

Effects of movement and movement imagery on somatosensory evoked magnetic fields following posterior tibial nerve stimulation.

We examined the "gating" effects caused by active and passive movements of toes and by "movement imagery" (mental moving of the toe without actual movements) on somatosensory evoked magnetic fields (SEFs) following stimulation of the posterior tibial nerve in normal subjects. Active and passive movements significantly attenuated the short- and middle-latency cortical components (P < 0.001) with no latency change, and the effects of the active movements were larger than those of the passive movements. In contrast, the subsequent long-latency component with a latency of about 100 ms was enhanced only by the active movements. Therefore, both centrifugal and centripetal mechanisms should be considered. The gating effects by movements on all components may occur in the primary sensory cortex (SI) in the hemisphere contralateral to the stimulated nerve, because all of the equivalent current dipoles (ECDs) of the components in the "control" and each "interference" waveform were located there. Active movements of the toes contralateral to the stimulated nerve caused no significant gating effect. The short-latency components were not consistently changed by "movement imagery", but the middle- and long-latency components were enhanced. Their ECDs were located in the SI contralateral to the stimulated nerve and in the SII in bilateral hemispheres. Therefore, we speculated that brain responses to somatosensory stimulation, particularly components generated in SII, were affected by volitional changes.

Adult↗

Goal-selection and movement-related conflict during bimanual reaching movements.

Conflict during bimanual movements can arise during the selection of movement goals or during movement planning and execution. We demonstrate a behavioral and neural dissociation of these 2 types of conflict. During functional magnetic resonance imaging scanning, participants performed bimanual reaching movements with symmetric (congruent) or orthogonal (incongruent) trajectories. The required movements were indicated either spatially, by illuminating the targets, or symbolically, using centrally presented letters. The processing of symbolic cues led to increased activation in a left hemisphere network including the intraparietal sulcus, premotor cortex, and inferior frontal gyrus. Reaction time cost for incongruent movements was substantially larger for symbolic than for spatial cues, indicating that the cost was primarily associated with the selection and assignment of movement goals, demands that are minimized when goals are directly specified by spatial cues. This goal-selection conflict increased activity in the pre-supplementary motor area and cingulate motor areas. Both cueing conditions led to larger activation for incongruent movements in the convexity of the superior parietal cortex, bilaterally, making this region a likely neural site for conflict that arises during the planning and execution of bimanual movements. These results suggest distinct neural loci for 2 forms of constraint on our ability to perform bimanual reaching movements.

Adolescent↗

Primary and coupled cervical movements: the effect of age, gender, and body mass index. A 3-dimensional movement analysis of a population without symptoms of neck disorders.

STUDY DESIGN: Exploratory experimental design. OBJECTIVES: To examine primary and coupled cervical movements, and to study the effects of age, gender, and body mass index in a "neck-healthy" population. These data could serve as a basis for future interventions and to assess normal variations. SUMMARY OF BACKGROUND DATA: Cervical movements are biomechanically and neurophysiologically complex. Neck disorders and trauma most often influence cervical movements. With 3-dimensional recordings, it is possible to make precise, noninvasive evaluations of how the head moves on the stable trunk, and to analyze primary and coupled movements. METHODS: A total of 120 subjects (60 men and 60 women, ages 20-79), were tested with Zebris (Zebris Medizintechnik GmbH, Isny, Germany), a 3-dimensional movement analyzer. RESULTS: Age influences the majority of primary and coupled movements. With increasing age, primary movement size decreases in all cardinal planes. Age most strongly affects the coupled movements of primary rotation and lateral flexion. Gender and body mass index have only slight influences. CONCLUSIONS: Coupled movements are a natural part of cervical motion together with primary movements and follow specific patterns in subjects with no symptoms of neck disorders. Our study shows that cervical motion alters throughout life according to specific patterns but with individual variations.

Adult↗

Reciprocal function of movement proteins and complementation of long-distance movement of Cymbidium mosaic virus RNA by Odontoglossum ringspot virus coat protein.

Complementation of movement and coat proteins of the orchid-infecting potexvirus Cymbidium mosaic virus (CymMV) and tobamovirus Odontoglossum ringspot virus (ORSV) was investigated. Nicotiana benthamiana, which is susceptible to both CymMV and ORSV, was used as a model system. Four transgenic lines, each harbouring one of the movement protein (MP) or coat protein (CP) genes of CymMV or ORSV, were constructed. The MP of CymMV consists of three overlapping open reading frames, together called the triple-gene block (TGB). CymMV and ORSV mutants, each carrying an inactivated MP or CP, were generated from the respective biologically active full-length cDNA clones. Complementation was studied by infecting transgenic plants with in vitro transcripts generated from these mutants. The cell-to-cell movement of a movement-deficient CymMV was restored in transgenic plants carrying the ORSV MP transgene. Similarly, CymMV TGB1 transgenic plants were able to rescue the cell-to-cell movement of a movement-deficient ORSV mutant. ORSV CP transgenic plants supported systemic movement of a CymMV CP-deficient mutant. However, in these plants, neither encapsidation of CymMV RNA with ORSV CP nor CymMV CP expression was detected. Long-distance movement of an ORSV CP-deficient mutant was not supported by CymMV CP. The complementation of MPs and CPs of CymMV and ORSV facilitates movement of these viruses in plants, except for long-distance movement of ORSV RNA by CymMV CP.

Capsid Proteins↗

Movement-related changes in oscillatory activity in the human subthalamic nucleus: ipsilateral vs. contralateral movements.

A voluntary movement is accompanied by a series of changes in neuronal oscillatory activity in the subthalamic nucleus (STN). These changes can be recorded through electrodes implanted for deep brain stimulation to treat Parkinson's disease in the time interval between the surgery and the internalization of the connections to the batteries. Both baseline activity and movement-related changes are different in the 'on' and 'off' medication motor states. In the 'off' state a low frequency activity in the alpha-beta range (8-25 Hz) that dominates the spectrum is interrupted during the movement, while in the 'on' state baseline frequencies are higher and a peri-movement gamma increase (70-80 Hz) is usually observed. Similar changes have been described with electrocorticographic recordings over the primary motor cortex but the gamma increase was only present during contralateral movements. We compared ipsi- and contralateral movement-related changes in STN activity, using a time-frequency analysis of the recordings obtained simultaneously in both STN and the scalp (electroencephalography) during right and left hand movements. The movement-related changes observed in the STN in the 'on' and the 'off' states were similar to those described previously in terms of predominant frequency bands, but we found bilateral changes in the STN during movements of either hand. A contralateral earlier start of the beta STN changes was mostly observed when the moving hand corresponded to the less-affected side, irrespective of hand dominance. These results suggest that movement-related activity in the STN has, by and large, a bilateral representation and probably reflects cortical input.

Aged↗

Perceptions of movement patterns: recall of movement.

The present study attempted to characterize the perception retention, and recall of kinaesthetic information regarding movement sequences (patterns). An attempt was made to draw on and extend conclusions relevant to simple movements (movement amplitude). One group of 10 blindfolded subjects recalled criterion movement patterns that had been actively commanded and 10 subjects recalled passively induced movements. The following conclusions were made. (1) Previous reports of algebraic errors in the recall of simple movement amplitudes are consistency with the finding that criterion perimeter, area, and depth of features were underestimated when recalled. (2) Measures of the accuracy of kinaesthetic perception do not alone account for the generally low level of pattern recall, the large range of individual differences or the underestimation of amplitude. The process of percept formation and of translating a percept into recalled movement are implicated. (3) Conclusions based on the short-term retention and recall of simple movements do not account for the coding, retention, and recall of movement sequences (patterns). (4) Percepts were formed, and patterns were recalled as a sequence of features but not as a sequence of key positions. (5) No direct difference was demonstrated between the recall of actively commanded and passively induced criterion movement patterns. However, the finding of a high gross angle change in the active condition was explained in terms of an unfavourable interaction between corollary discharge and sensory information.

Female↗

[Working memory for movement patterns: a direct comparison of memory spans for body and hand movements in dual-task situations].

In this experiment, 36 participants engaged in one of three span tasks; digit span, body movement span, or hand movement span task, in which they were asked to remember visually presented sequences of digits, whole body movement patterns, or hand movement patterns, respectively. As in a standard memory span procedure, the items within each sequence were recalled in order. Participants were presented with increasingly longer sequences of the items, and span score was defined as the number of items in the longest sequence a participant could recall perfectly. The span tasks were tested under three concurrent task conditions; no concurrent task control, concurrent articulation task, and concurrent body-related movement task. The concurrent movement task interfered with performance on both body movement and hand movement span tasks, but not on the digit span task, while the concurrent articulation task interfered with performance on all of the three span tasks. It is suggested that memory for movement patterns, which is involved in the body and band movement spans, would be mediated by a common motor-processing system.

Hand↗

The effect of movement velocity and movement pattern on the reciprocal co-activation of the hamstrings.

The effect of velocity and movement pattern (reciprocal vs. non-reciprocal) on the reciprocal co-activation of the hamstrings was investigated through analysis of the root mean square (RMS) and the median frequency (MDF) of surface electromyography (SEMG). Fourteen subjects performed six continuous repetitions of a reciprocal isokinetic movement pattern (maximal extension followed by maximal flexion), and six continuous repetitions of a non-reciprocal movement pattern (maximal extension only) at 100 degrees, 200 degrees, 300 degrees s-1, and 400 degrees s-1. Data were analyzed using separate 2 x 4 (movement pattern x angular velocity) repeated measures analysis of variance (ANOVA). No significant differences (p > 0.05) were noted between reciprocal and non-reciprocal movement patterns for RMS. However, results did reveal a velocity effect for RMS (F = 5.0, p < 0.01), with significant differences observed between 100 degrees s-1 and 400 degrees s-1 (F = 9.4, p < 0.01), 200 degrees s-1 and 400 degrees s-1 (F = 9.5, p < 0.01), and 300 degrees s-1 and 400 degrees s-1 (F = 11.0, p < 0.001), with RMS values at 400 degrees s-1 being the highest. There was also a velocity effect for MDF (F = 8.03, p < 0.001), with significant differences observed between 100 degrees s-1 and 300 degrees s-1 (F = 4.2, p < 0.05), 100 degrees s-1 and 400 degrees s-1 (F = 20.2, p < 0.0001), 200 degrees s-1 and 400 degrees s-1 (F = 15.221, p < 0.001), and 300 degrees s-1 and 400 degrees s-1 (F = 5.9, p < 0.01). In all cases the highest MDF values were exhibited at the lower velocities. Lastly, there was an interaction effect when comparing movement patterns at 400 degrees s-1, with MDF values being significantly higher during the non-reciprocal movement pattern than during the reciprocal movement pattern (F = 10.9, p < 0.01). Results indicated that during isokinetic movements, RMS and MDF activity of the hamstrings are altered as velocity changes. More specifically, as velocity increases overall hamstrings' co-activation increases and there is a shift in the power spectrum toward the recruitment of slower-twitch muscle fibers. Results also indicate that movement pattern (reciprocal vs. non reciprocal) does not effect appreciably SEMG activity of hamstrings' co-contraction.

Adult↗

The force requirements for tooth movement, Part I: Tipping and bodily movement.

Specific data on the relation between force and tooth movement is essential not only to facilitate non-traumatic orthodontic treatment but also to establish a sound basis for appliance design. Whilst the broad approaches to orthodontic tooth movement appear to be the application of tipping and/or bodily movement, no scientific comparison between these two types of movement has yet been made. This article describes experiments which repeat investigations of Storey and Smith into the relation between the force applied and the rate of tipping movement and their extension to include bodily movement. Twenty adolescent male patients requiring distal movement of upper cuspid teeth as a part of orthodontic treatment were each fitted with calibrated cuspid retraction springs. The appliances were designed to induce bodily movement on one side of the mouth concurrently with tipping movement on the other. Initial force applications were identical, and the experiments lasted for up to eleven weeks following one activation of the retraction springs. The results of these experiments were compared with those of other workers, and an explanation of the causes of the past controversy regarding various theories of tooth movement is offered.

Adolescent↗

Pre-movement activity of neurons in the parietal associative cortex of the cat during different types of voluntary movement.

Pre-movement activation of electromyographic spike activity of 201 neurons of field 5 was studied in cats trained to carry out a stereotypical act (lifting the anterior footpad to press a pedal) in response to a conditioned stimulus (experimental series 1) and without a conditioned stimulus (self-initiated movement, experimental series 2). In series 1, 69.2% of neurons were activated and 13.5% were inhibited before the movement. Prior changes in activity were also seen in intersignal movements, with activation of 40.6% and inhibition of 21.7% of neurons. The time parameters of excitatory and inhibitory responses in both situations were similar, with pre-movement intervals of 19-1640 msec. In series 2, pre-movement inhibition was seen rather more frequently than activation (36.7% and 33.7% respectively). The earliest changes were inhibitory, occurring some 1800 msec before movements, while excitatory changes occurred only 880 msec before movement. These data indicate the involvement of the parietal associative area in the can not only in executing, but also in preparing for different types of movement, including self-initiated movements, and that inhibition has an active role in this process.

Action Potentials↗

Speech-related body movement in aphasia: period analysis of upper arms and head movement.

The effects of aphasia on coverbal body movement have important implications for the understanding of both normal and pathological speech processes. The related findings were often inconsistent, partly due to inherent methodological difficulties which could be reduced by the use of advanced techniques of movement monitoring (Hadar, 1991). The present study employed a new computerized system, CODA-3, which locates small prismatic markers and computes by triangulation their three-dimensional position at 100 Hz. Movement of the head and the upper arms was monitored in 15 aphasic and normal subjects engaged in speech during a naturalistic interview. Movement analysis was based on automatized identification of successive movement extrema ("period analysis") and the computation of amplitude, duration, and velocity of each period. The results showed higher incidence and amplitude of all body movement in the aphasic population. Fluent aphasics showed this particularly with "symbolic," content-bearing movements, while nonfluent aphasics were higher than controls in both symbolic and "motor" (simple and small) movements. No deficit in the internal organization of movement was seen in the aphasic population. These results indicate that aphasics increase their coverbal movement in compensation for their speech impairment: fluent aphasics compensate primarily for a symbolic impairment, while nonfluent aphasics compensate more for a motor impairment.

Adult↗

Premotor cortex of monkeys: set- and movement-related activity reflecting amplitude and direction of wrist movements.

1. Neuronal activity was recorded from the premotor cortex (PM) of Japanese monkeys while they performed hand movements with different amplitudes and directions. On each behavioral trial, two instructions were given sequentially: 1) an amplitude instruction (large or small) and 2) a direction instruction (flexion or extension). The onset of movement was triggered by a visual signal after a delay period. 2. Among various kinds of task-related neuronal activity recorded in the PM, two types were selected for study: 1) set-related activity, sustained activity change during the delay period that followed presentation of instruction signals (IS); and 2) movement-related activity, activity change immediately before and during movement, which followed the trigger signal (TS) presentation. 3. Thirty-two of 101 set-related neurons showed activity change after presentation of the first IS (Delay 1 set-related activity), when they were instructed in either amplitude or direction, but not both. All of the set-related neurons showed activity modulation after presentation of the second IS (Delay 2 set-related activity). When neurons showed both Delay 1 and Delay 2 set-related activity, they were usually more active during Delay 2, i.e., when the monkeys had received both amplitude and directional ISs. A majority of neurons with Delay 2 set-related activity (64%) showed relation to both movement amplitude and direction. Twenty-eight percent of the neurons showed relation to either amplitude or direction, but not both. These findings seem consistent with a view that serial, rather than parallel, processes of motor programming operate in preparation of intended movements. 4. A majority of PM neurons with movement-related activity (51%) showed activity change related to both the direction and amplitude of movement. Forty-two percent showed selective relation to either direction or amplitude. These findings support a view that PM contributes to the control of limb movements. 5. Histological reconstruction showed that a vast majority of PM set-related neurons were located in the dorsal aspect of the PM (PMd), medial to the arcuate spur and lateral to the superior precentral sulcus. In contrast, movement-related neurons were distributed in two distinct foci: one in the ventral aspect of the PM (PMv), immediately caudal to the genu of the arcuate sulcus and lateral to the spur of the sulcus; and the other in the PMd, overlap;ing the location of set-related neurons.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗

Advance movement preparation of eye, foot, and hand: a comparative study using movement-related brain potentials.

The present study was designed to test the inter-relationship between generalized motor programs (GMPs) and movement preparation by asking participants to perform movements with eye, foot, or hand. In two independent experiments a response precuing task was employed that combined the recording of movement-related brain potentials (MRPs) with dipole source analysis. Behavioral results indicated the utilization of advance information about movement direction and effector. When eye and hand movements were involved (experiment1) partial advance information about response side but not effector induced parallel motor programming of eye and hand at an abstract but not effector-specific level. In contrast, when partial precues specified side of a forthcoming hand or foot movement (experiment 2) foot and hand were prepared in parallel both at abstract and at effector-specific levels of motor programming. Consistent with the GMP view, these results indicate that effector-specific preparation is possible even when the effector is not yet known as long as a common motor program controls the demanded movements. However, because parallel specification of divergent movement pattern (eye, hand) at an abstract level was not predicted by the GMP, we propose a model of advance movement preparation that takes into account neurofunctional considerations.

Adult↗