Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Movement”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,225 records · Page 68Linked to original sources
PubMed2006

Organophosphate intoxication-related coital-like involuntary movements: report of A case.

The neurologic manifestations of organophosphate intoxication are many, and different pathophysiologic mechanisms are responsible for the different presentations occurring at different stages of the disease process. Movement disorders constitute one of the neurologic manifestations, which may include Parkinsonism or other dyskinetic movements. However, involuntary coital-like movements have not been reported as one of the organophosphate intoxication-related movement disorders. In this case report, we describe a 71-year-old man who developed involuntary coital-like movements about one and a half months after an event of organophosphate intoxication in an attempt to commit suicide. The involuntary movements were to-and-fro pelvic thrusting and back-rocking movements. The patient was able to suppress the involuntary movements for a short period of time, although they usually persisted all day long. The involuntary movements occurred in all postures including standing, sitting and in supine postures, resulting in great embarrassment. These involuntary movements also interfered with the initiation of sleep, although they discontinued while asleep. With clonazepam and piracetam therapy, the involuntary coital-like movements of this patient decreased in amplitude, although remaining to a degree even after one year of follow-up.

Aged↗
PubMed2006

[Expression of transforming growth factor beta1 and insulin-like growth factor I in the regenerated bones after low frequency micro movement].

OBJECTIVE: To investigate the expression of transforming growth factor beta1 (TGF-beta1) and insulin-like growth factor I (IGF-I) in new bone after low frequency micro movement. METHODS: Fifteen female sheep from Shandong province were involved in the study and their bilateral tibias transversely osteotomized in the middle shafts with a defect of 2 mm. The hind limbs were fixed with unilateral external fixators connected to a controlled micro movement device. Ten days after osteotomy, one hind limb of each sheep randomly was selected to perform micro movement at an amplitude of 0. 25 mm and a frequency of 1 Hertz, 30 min a day for 4 weeks (micro movement group). The other hind limb served as the control group. Five sheep were sacrificed at 3, 4 and 6 weeks after osteotomy, respectively, and specimens were harvested for detecting the expression of TGF-beta1 and IGF-I by immunohistochemistry and RT-PCR. RESULTS: Immunohistochemistry: In the third postoperative week in the micro movement group, the expression of TGF-beta1 was detected in different areas of new chondrocytes at the margin of callus, mainly in proliferating area, and IGF-I expressed in osteoblasts at the margin of endochondral ossification area, calcified and mature chondrocytes and osteocytes. There was seldom expression of IGF-I and little expression of TGF-beta1 in the corresponding area in the control one. In the 4th postoperative week in the micro movement group, the expression of TGF-beta1 diminished gradually with the mature of new bone and be located in extracellular matrix and osteoblasts around ossified areas; The expression of IGF-I reached the peak and be located mainly in osteoblasts of new bone surface, maturing osteocytes and calcifying osteoid. But there was little expression of them in the control group. In the sixth postoperative week in the micro movement group, there was a little expression of IGF-I expression but little expression of TGF-beta1; there was nearly no expression of them in the control group. In the micro movement group, the absorbance values of TGF-beta1 at 3 and 4 weeks and of IGF-I at 3, 4 and 6 weeks were significantly higher than those in control group (P<0. 05). RT-PCR: In the third and fourth postoperative weeks in the micro movement group, there was higher expression of mRNA of TGF-beta1 and TGF-I than those in control group; in the sixth postoperative week, the expression diminished gradually, but was higher than that in control group. The absorbance values of TGF-beta1 at 3 and 4 weeks and IGF-I at 3, 4 and 6 weeks were significantly higher than those of control group (P<0. 05). CONCLUSION: Low frequency and controlled micro movement in the early stage of the fracture healing can promote the expression of TGF-beta1 and IGF-I. They worked together to regulate the process of the endochondral ossification, while in the late stage the differentiation of osteocytes and mineralization of osteoid were regulated mainly by IGF-I, which played an important role in regulating the cell biological behavior during micro movement.

Animals↗
PubMed1989

[Choreic movements and dopamine--implications to the underlying neural mechanisms involved].

Choreic movement is one of the most attractive involuntary movements in terms of searches for the underlying mechanisms. Huntington's disease is a most popular disorder exhibiting choreic movements, in which the rather selective striatal degeneration is postulated to be responsible for the generation of choreic movements. In this respect, we have recently produced an experimental model of choreic movements in monkey by combined methods of kainic acid injection into the unilateral striatum and the oral administration of L-DOPA. The purpose of this paper is to summarize our experiment and to review the previous papers on experimental model of choreic movements in order to shed light on the underlying mechanisms of choreic movements. There are at least following three possible mechanisms in the generation of choreic movement. 1) A massive loss of GABAergic inhibitory neurones in the striatum induces disinhibitory effects on nigral dopaminergic neurones, which causes activation of dopaminergic neurones and choreic movements. However, a loss of GABA in the nigra does not always correlate with the generation of choreic movements. 2) A hypersensitive receptors for dopamine in the striatum may cause choreic movements. In fact, however, dopamine receptors are decreased or normal rather than increased not only in Huntington's disease but also in monkey models. 3) A massive loss of neurones in the striatum causes a loss of post-synaptic components of dopaminergic terminals. This may further cause rearrangements and compensatory changes in dopaminergic terminals in the spared striatum. These changes may activate pre-synaptic dopaminergic components which are further activated by the administration of L-DOPA. This hypothesis is mainly derived from the experimental model in monkey.

Animals↗
PubMed1989

[A clinical study on the relationship between chewing movements and masticatory muscle activities].

Chewing movement is one of the most important functional and physiological jaw movements, and it is coordinated by the three elements of the functional occlusion system (teeth, TMJs and masticatory muscles). However, the relationship between chewing movement and these elements has not been clarified. The purpose of this study was to investigate the relationship between chewing movement and the activity of the masticatory muscles which directly control jaw movements. 25 subjects with normal stomatognathic function, 5 patients with MPD syndrome (muscle dysfunction group) and 5 patients with unilateral TMJ internal derangement (TMJ dysfunction group) were selected. 6 gums with different hardness were used as the test bolus. Sirognathograph Electromyograph Analysing System was used to simultaneously record chewing movements and electromyograms of the right and left masseter, anterior temporal, posterior temporal and anterior belly of digastric muscles. Using the analysing software which was developed for this study, chewing movements and muscle activities were analysed. The results were as follow; A. In normal subjects 1. Gum hardness influenced durations of the closing and occluding phases, maximum opening and closing speed, opening degree and deviation of opening and closing path. 2. Gum hardness influenced muscle activities except of the time factors of digastric bursts. 3. Durations of the closing and occluding phases were found to be related with the elevator muscle activities. Maximum closing speed was related with the masseter and anterior temporal muscle activities. Deviation of closing path was related with the anterior and posterior temporal muscle activities. B. In abnormal subjects 1. The changes mainly observed in the muscle activities were found to be significantly different between the muscle dysfunction group and normal group. Similarly, the changes mainly observed in the chewing movements were different between the TMJ dysfunction group and normal group. 2. When compared with the relationships in normal subjects, changes were observed in the relationships for closing movement in the muscle dysfunction group. In contrast, changes were observed in the relationships for opening movement in the TMJ dysfunction group. From the results, close relationships were found between chewing movements and muscle activities, and were characteristically influenced by stomatognathic dysfunction.

Adolescent↗
PubMed1979

Stimulation of breathing movements in fetal sheep by inhibitors of prostaglandin synthesis.

We studied the effects of inhibitors of prostaglandin synthesis on fetal breathing movements on 17 occasions in 11 lambs (gestational age 125-141 days). We gave 12 h infusions of sodium mechlofenamate (8.6-22.2 mg.kg-1) in 13 studies and indomethacin (21.8-38.8 mg.kg-1) in four studies. Results were similar with both agents and did not correlate with drug dosage. There were no changes in fetal arterial blood pressure, pH or blood gas tensions. We assessed fetal breathing movements by measurements of tracheal pressure for a control period of 224 h prior to and 208 h during the infusion of inhibitors of prostaglandin synthesis; their administration caused a marked stimulation of fetal breathing movements judged from the following four variables: (1) incidence of fetal breathing movements increased from 38.4 to 69.2% of the time (P < 0.001); (2) average amplitude of change in tracheal pressure during fetal breathing movements increased from 4.1 to 6.0 torr (P < 0.01); (3) maximal amplitude of change in tracheal pressure during fetal breathing movements increased from 8.8 to 13.4 torr (P < 0.01); and (4) the duration of the longest continuous episode of fetal breathing movements increased from 37 to 229 min (P < 0.05). Two fetuses had electrocorticogram (ECoG) recordings. In control periods, fetal breathing movements occurred only during low voltage, high frequency ECoG activity; however, during infusions of inhibitors of prostaglandin synthesis, fetal breathing movements occurred also during high voltage, low frequency ECoG activity. We conclude that inhibitors of prostaglandin synthesis stimulate fetal breathing movement in fetal sheep. These results suggest that a component of the prostaglandin system is a factor which inhibits breathing movements during fetal life.

Animals↗
PubMed1982

[Intrauterine fetal movements and their significance for the condition of the fetus].

A literature review reports the results of investigations about fetal intrauterine activity. Different methods of observation are demonstrated and discussed. The results indicate that real-time-ultrasound is an accurate method for observation of fetal movements. Different patterns are identified: 1. Fetal body and extremity movements Development of fetal activity in early pregnancy is looked at as a process of maturation associated with fetal cerebral function. After 12 weeks of pregnancy typical patterns are established and seen also in the following weeks. Different results are reported about frequency of fetal movements related to duration of pregnancy. A circadian rhythm seems to be associated with a peak in activity between 2100 and 0100 hours, although fetal activity is altered by a variety of drugs and external stimuli. The proportion of pathological foetal movements in early pregnancy seems higher in patients who aborted. There are findings in later pregnancy, which report good fetal outcome, if daily fetal movement recording is greater than 10 movements for 12 hours. 2. Fetal breathing movements are recognized as being normally present, but episodic, shallow and variable in rate and regularity. There is a great variability in the percentage of time fetuses spend making breathing movements (mean 30-50% per hour; range 0-80%). Under physiological conditions there is a circadian rhythm concomitant with changes in fetal low-voltage electrocortical activity. The activation of fetal breathing occurs mainly during rapid-eye-movement-sleep, but the physiologic control of the activation has not been identified. Apnea, frequency, variability and amplitude of breathing, continuous breathing or gasping are described, but positive identification of abnormal pattern is not achieved. Several factors affecting fetal breathing movements have been described, their physiologic significance and control and their clinical relevance remain to be clearly elucidated. 3. Total fetal activity Fetal biophysical variables such as tone, breathing, body and extremity movements and heart rate reactivity are initiated and regulated by the fetal central nervous system, and as such, the presence of a given variable is indirect evidence of a functioning and intact central nervous system. These variable could be depressed by hypoxemia or other factors. Data in literature suggest that combined fetal biophysical testing is a more accurate method of antepartum fetal evaluation than any single method.

Circadian Rhythm↗
PubMed1993

Step-tracking movements of the wrist. III. Influence of changes in load on patterns of muscle activity.

Human subjects performed step-tracking movements of the wrist in the radial direction. Movement amplitude, external load, and accuracy instructions were varied. We used surface electrodes to record muscle activity from an agonist, extensor carpi radialis longus, and an antagonist, extensor carpi ulnaris. When subjects performed movements "as fast as possible" that were opposed by different external loads, we observed two distinct patterns of modulation of the agonist burst. In one pattern, termed pulse-height modulation, the force of the agonist muscle was graded by varying the peak amplitude of a short-duration agonist burst. This pattern occurred when subjects performed movements of different amplitudes with a lightweight manipulandum. In the other pattern, termed pulse-width modulation, the force of the agonist muscle was graded by varying the duration of an agonist burst of nearly maximal amplitude. When the agonist burst was prolonged, the onset of antagonist activity was delayed. This pattern occurred when subjects performed movements of different amplitudes that were opposed by elastic or viscoelastic loads applied to a heavy manipulandum. The strongest subject exhibited more pulse-height modulation and less pulse-width modulation of the agonist burst than other subjects. Conversely, the weakest subject displayed more pulse-width modulation of the agonist burst than other subjects. These observations indicate that the force requirements of a task, relative to the force generating capacity of a subject's agonist muscle(s), have a significant influence on the pattern of agonist modulation. In a second experiment using three nonhuman primates, we observed that agonist bursts in wrist flexor and extensor muscles exhibited strikingly different patterns of modulation. For wrist flexion, agonist bursts in wrist flexors were brief and displayed pulse-height modulation when movement amplitude was varied. For wrist extension, agonist bursts in wrist extensors were prolonged and displayed largely pulse-width modulation when movement amplitude was varied. We suggest that the distinct patterns of modulation observed in the wrist muscles of monkeys were due to differences in the strength of wrist flexors and extensors, rather than to alterations in movement strategy. In a third experiment, we instructed human subjects to be "accurate" when they made step-tracking movements. When subjects performed movements with a lightweight manipulandum, most displayed short-duration agonist bursts that were pulse-height modulated. When subjects performed "accurate" movements that were opposed by elastic loads, they displayed pulse-width modulation of a small-amplitude agonist burst.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1995

Assessing the outcome of making it easier for patients to change general practitioner: practice characteristics associated with patient movements.

BACKGROUND: The government white paper, Promoting better health, suggested that primary health care services should be made more responsive to patient needs and that competition, brought about by the freer movement of patients between practices, could act as a mechanism for improving the quality of the services provided. Policy changes reflecting these aims were introduced with the 1990 contract for general practitioners. AIM: A study was carried out to estimate the volume of patient movement between practices not attributable to a patient's change of address or to a major change in the practice they had left, and to investigate which practice characteristics patients moved towards and which they moved away from when changing general practitioner. METHOD: Data on 2617 patient movements during June 1991 were collected from five family health services authorities. These patient movements were analysed in relation to data on practice characteristics obtained from family health services authority records. RESULTS: The estimated volume of movement of patients between practices was small (1.6% of the registered population per year). The majority of movements were between group practices; a quarter of the movements recorded were to single-handed general practitioners. However, the ratio of the number of movements from group practices to single-handed general practitioners compared with those from single-handed general practitioners to group practices was 1.37 (95% confidence interval 1.19 to 1.57). In choosing single-handed general practitioners these patients were willing to forgo access to a woman general practitioner, extended services and greater hours of general practitioner availability. Among the subset of movements between group practices, patients were more likely to gain access to a practice nurse, longer surgery hours and a woman general practitioner as a consequence of their move. CONCLUSION: The scale of patient movement observed did not indicate any substantial mechanism by which the new policy of encouraging consumerist behaviour on the part of primary care users could effect desired changes in primary care practice. Among the patient movements observed, the evidence suggests that when choosing a practice potential patients were not deterred by the fact that a practice was single-handed. The public's perception of the factors contributing to a high quality of service may conflict with the official characterization of good practice and high quality services in primary health care.

Adolescent↗
PubMed1999

Fetal and neonatal hand movement.

BACKGROUND AND PURPOSE: Fetal movement occurs early in human gestation and can be observed by ultrasound imaging. This was a descriptive study of fetal hand movements from 14 weeks of gestation to postnatal day 1. The purpose of the study was to identify specific hand movements and their developmental trends in order to better understand low-risk human development. SUBJECTS: Twenty-one women with low-risk pregnancies were identified from a university obstetrics clinic. Their fetuses or neonates were the focus of this study. METHODS: Ultrasound imaging was used at 14, 20, 26, 32, and 37 weeks of gestation, and videotaping was used at 1 day after birth. Between 12 and 16 minutes of usable imaging was obtained at each fetal age, and 24 minutes of videotape was collected neonatally. The duration and frequency of 7 hand movements were determined and reliably scored. Nonparametric analyses were used. RESULTS: Fetal and neonatal movements did not appear to be random, and they appeared to be directed or aimed at specific targets. Fetal movement was variable throughout gestation. Differences occurred between fetal and neonatal data. Durations of certain hand movements provided data that exhibited some developmental trends, such as decreasing linear trends and regression-type U curves. Fetal movements to or at the head and face and the observations scored at 32 weeks of gestation were the best predictors of neonatal movement. CONCLUSION AND DISCUSSION: Results suggest the potential for fetal movement to be observed and scored reliably, with scores used to further our understanding of the development of human movement.

Embryonic and Fetal Development↗
PubMed1997

Arm-movement-related neurons in the primate superior colliculus and underlying reticular formation: comparison of neuronal activity with EMGs of muscles of the shoulder, arm and trunk during reaching.

Neuronal activity was recorded from the superior colliculus (SC) and the underlying reticular formation in two monkeys during an arm reaching task. Of 744 neurons recorded, 389 (52%) clearly modulated their activity with arm movements. The temporal activity patterns of arm-movement-related neurons often had a time course similar to rectified electromyograms (EMGs) of particular muscles recorded from the shoulder, arm or trunk. These reach cells, as well as the muscles investigated, commonly exhibited mono- or biphasic (less frequently tri- or polyphasic) excitatory bursts of activity, which were related to the (pre-)movement period, the contact phase and/or the return movement. The vast majority of reach cells exhibited a consistent activity pattern from trial to trial as did most of the muscles of the shoulder, arm and trunk. Similarities between the activity patterns of the neurons and the muscles were sometimes very strong and were especially notable with the muscles of the shoulder girdle (e.g. trapezius descendens, supraspinatus, infraspinatus or the anterior and medial deltoids). This high degree of co-activation suggests a functional linkage, though not direct, between the collicular reach cells and these muscles. Neuronal activity onset was compared with that of 25 muscles of the arms, shoulders and trunk. The majority of cells (78.5%) started before movement onset with a mean lead time of 149+/-90 ms, and 36.5% were active even before the earliest EMG onset. The neurons exhibited the same high degree of correlation (r=0.97, Spearman rank) between activity onset and the beginning of the arm movement as did the muscles (r=0.98) involved in the task. The mean neuronal reach activity (background subtracted) ranged between 7 and 193 impulses/s (mean 40.5+/-24.2). The mean modulation index calculated [(reach activity background activity)/reach activity+background activity)] was 0.75+/-0.23 for neurons (n=358) and 0.87+/-0.14 for muscles (n=25). As the monkeys fixated the reach target constantly during an arm movement, neuronal activity which was modulated in this period was not related to eye movements. The three neck muscles investigated in the reach task exhibited no reach-related activity modulation comparable to that of either the reach cells or the muscles of the shoulder, arm and trunk. However, tonic neck muscle EMG was monotonically related to horizontal eye position. The clear skeletomotor discharge characteristics of arm-movement-related SC neurons revealed in this study agree with those already known from other sensorimotor regions (for example the primary motor, the premotor and parietal cortex, the basal ganglia or the cerebellum) and are consistent with the possible role of this population of reach cells in the control of arm movements.

Animals↗
PubMed2004

The effect of directional compatibility on the response latencies of ocular and manual movements.

Visuomotor coordination is essential for the successful performance of everyday activities, and it could be affected by the directional compatibility between ocular and manual movements. Many tasks, such as driving or operating devices in the workplace, require a variety of coordination patterns with different levels of compatibility between the eyes and the hand. For example, the movement of the eyes and the arm can be coupled when both effectors point towards the same direction whereas in other tasks the movement of the eyes and the arm can be dissociated, for instance when a peripheral object is foveated while a button press response is executed concurrently. The objective of this study was to examine the latency of ocular and manual movements in tasks characterized by variations in directional compatibility. Four tasks were used to manipulate compatibility: 1. point and look at a peripheral stimulus (POINT AND LOOK)--high directional compatibility; 2. point to a peripheral stimulus while fixating in the center (POINT AND FIXATE)--low directional compatibility; 3. press a button while looking at a peripheral stimulus (PRESS AND LOOK)--low directional compatibility; and 4. press a button while fixating in the center (PRESS AND FIXATE)--no directional motor requirement. We hypothesized that the latency of (1) manual and (2) ocular responses would be faster in the task with high directional compatibility compared with the tasks with low compatibility or the task with no directional motor component. Ten healthy participants executed pointing and pressing movements with and without concurrent eye movement to randomly presented visual stimuli. In agreement with the first hypothesis, results showed that in a task with high directional compatibility, manual responses were initiated significantly faster when compared with the tasks with low compatibility or a task with no directional motor component: 1. pointing while looking was initiated 22 ms faster on average than pointing while fixating; 2. pointing while looking was initiated 91 ms faster than pressing accompanied by an eye movement; and 3. pointing while looking was initiated 102 ms faster than pressing while fixating. The second hypothesis was partially supported by data which showed that eye movements directed toward peripheral stimuli were initiated significantly more slowly (30 ms on average) when accompanied by pressing in comparison with the latency of eye movements in the high-compatibility task. In contrast with the hypothesis, eye movements that were accompanied by pointing were not initiated faster than those in a task which required looking without pointing. In summary, these data suggest that directional compatibility is an important aspect of motor control. The effects of directional compatibility are discussed in a conceptual framework that considers the neurophysiological substrates that might be involved in mediating these effects.

Adolescent↗
PubMed2006

Development of head movement propensity in 4-15 year old children in response to visual step stimuli.

Head movement frequency of children in response to horizontal step stimulus is investigated. The aim is to determine if there is a correlation between the age of the child and the frequency of head movements made to visual step stimuli presented at a fixed distance. Also of importance is whether there is a period of rapid change in the frequency of head movements, and if so, what factors could be influencing this change. Seventy-three participants, between the ages of 4 and 15 years were requested to "look at a spot of light" in response to step stimuli which varied in size from 5 to 60 degrees. Eye and head movements were recorded with a video based eye tracker (EL-Mar 2020) equipped with a Flock of Birds head tracker. Frequency of head movements was calculated for each participant and averaged across participants for each age group. Average head movement frequency was then plotted as a function of age. The frequency and variability of head movements decreases as a function of age. This decrease is linear between the ages of 4 and 15 years (y = -1.465x + 22.58; R(2) = 0.4378; F = 26.48; P < 0.0001). More head movements are made in response to larger step sizes than to smaller ones for all ages. The gradual decrease in frequency of head movements in response to step stimuli suggests that a specific environmental event, such as reading, is not the cause of the decline. Improved efficiency of eye movements could be due to pre-programmed factors related to neurological development. Alternatively, cognitive factors may be involved. Children may actually learn that utilizing their head for gaze shifts is more energy and time consuming, than merely using the eyes alone.

Adolescent↗
PubMed2004

Left hemisphere specialization for the control of voluntary movement rate.

Although persuasive behavioral evidence demonstrates the superior dexterity of the right hand in most people under a variety of conditions, little is known about the neural mechanisms responsible for this phenomenon. As this lateralized superiority is most evident during the performance of repetitive, speeded movement, we used parametric rate variations to compare visually paced movement of the right and left hands. Twelve strongly right-handed subjects participated in a functional magnetic resonance imaging (fMRI) experiment involving variable rate thumb movements. For movements of the right hand, contralateral rate-related activity changes were identified in the precentral gyrus, thalamus, and posterior putamen. For left-hand movements, activity was seen only in the contralateral precentral gyrus, consistent with the existence of a rate-sensitive motor control subsystem involving the left, but not the right, medial premotor corticostriatal loop in right-handed individuals. We hypothesize that the right hemisphere system is less skilled at controlling variable-rate movements and becomes maximally engaged at a lower movement rate without further modulation. These findings demonstrate that right- and left-hand movements engage different neural systems to control movement, even during a relatively simple thumb flexion task. Specialization of the left hemisphere corticostriatal system for dexterity is reflected in asymmetric mechanisms for movement rate control.

Adolescent↗
PubMed2000

Temporal coordination between mandibular and head-neck movements during jaw opening-closing tasks in man.

Previous finding of concomitant mandibular and head movements during jaw function suggest a functional relation between the human jaw and neck regions. This study examined the temporal coordination between mandibular and head-neck movements during maximal jaw opening-closing tasks, at fast and slow speed. Twenty-four healthy individuals, median age 25 years, participated in the study. They were seated with firm back support but without head-neck support. Mandibular and head movements were simultaneously monitored by a wireless optoelectronic system for three-dimensional movement recording. The timing of head movement in relation to mandibular movement was estimated at defined time-points (start, peak, end and maximum velocity of movement), and during the entire course of the jaw-opening and jaw-closing phases. The results showed that the head in general started to move simultaneously with or before the mandible, reached the peak position simultaneously with, before or after the mandible, and reached the end position after the mandible. A higher degree of temporal coordination was found for fast speed at the start and the peak positions. The head most often attained maximum velocity after the mandible, and mostly lagged behind the mandible during the entire jaw-opening and -closing phases. These findings support the notion of a functional linkage between the human temporomandibular and craniocervical regions. They suggest that "functional jaw movements" comprise concomitant mandibular and head-neck movements which involve the temporomandibular, the atlanto-occipital and the cervical spine joints, and are caused by jointly activated jaw and neck muscles. It is proposed that these jaw and neck muscle actions, particularly at fast speed, are elicited and synchronized by preprogrammed neural command(s) common to both the jaw and the neck motor systems. From the present results and previous observations of concurrent jaw and head movement during fetal yawning, we suggest that these motor programmes are innate.

Adult↗
PubMed1991

Brain potentials associated with movement in traumatic brain injury.

Brain potentials may be used to assess the functional abnormalities that underlie impairments of movement. The purpose of this article is to illustrate the usefulness of examining these potentials. In addition to an overview of the topic, the article includes a report of a study demonstrating that there were differences between the brain potentials of five patients with traumatic brain injury and those of four healthy control subjects. All five patients were in the postacute phase of hemiplegia. Slow cortical potentials associated with simple goal-directed forearm and finger movements were recorded from frontal and parietal electrodes. Two seconds of movement-related electroencephalographic activity (movement-related potential) were recorded. The patients showed reduced brain potentials for movements associated with their paretic limb and, to a lesser extent, reduced brain potentials for movements associated with their nonparetic limb. The waveforms obtained from the patients were unusual, with uncharacteristic cross-cortical movement-related potential correlations associated with specific electrode configurations, as well as with specific movement conditions. Brain potentials associated with the fore-period interval of a simple reaction time paradigm were later recorded in two of the patients with traumatic brain injury and in a control subject to help determine the functional significance of the relative positivity apparent in their movement-related potential data. This preliminary study indicates that electroencephalographic potentials obtained during the preparation for and execution of movement can provide information regarding the basis for motor dysfunction.

Adolescent↗
PubMed1979

Vestibulo-ocular function during co-ordinated head and eye movements to acquire visual targets.

1. Experiments have been conducted on human subjects in an attempt to establish the role of the vestibulo-ocular reflex in the co-ordination of head and eye movements during visual target acquisition. 2. When the subject moved head and eyes to acquire visual targets in the horizontal plane, the eye movement consisted of an initial saccade in the direction of head movement followed by a slower return towards orbital centre which compensated for remaining head movement. 3. When the head was moved either voluntarily or passively in the dark the pattern of eye movement was very similar to that seen during target acquisition. 4. The mean latency between the start of head acceleration and the onset of the saccadic eye movement was greater in the dark (108 msec, S.D. 85 msec) than for the visually induced responses (14 msec, S.D. 59 msec), in which eye movement often preceded head movement when moving to small ( less than 45 degrees) target offset angles. 5. In all experimental conditions gaze displacement at the end of the initial saccade was normally related in a predictive manner to final head position, but when fixating visual targets offset by more than 60 degrees from the central position there were often large errors, 22% of responses undershooting the target by more than 15 degrees. 6. A highly significant (P less than 0.001) linear relationship was found between gaze displacement and head velocity under all experimental conditions. During target acquisition head velocity was normally positively correlated with amplitude of target offset. The large errors in gaze displacement in response to the larger target offsets occurred at levels of head velocity lower than normally associated with such target offsets. 7. The results have led to the suggestion of a dual mode of control for head-eye co-ordination. In one mode, normally associated with small target offsets (less than 45 degrees), control is mediated by retinal error information. In the other mode, associated with larger target offsets, gaze displacement is generated as an automatic response to head turning. 8. The observation of similar relationships between head and eye movement during passive head turning implicates the vestibulo-ocular reflex in the secondary mode of control, and provides support for the hypothesis that the role of the vestibular saccade is to induce a rapid offset of the eyes in the direction of head movement, thus facilitating rapid search and target location.

Eye Movements↗
PubMed2003

Defensive movements evoked by air puff in monkeys.

Electrical stimulation of two connected cortical areas in the monkey brain, the ventral intraparietal area (VIP) in the intraparietal sulcus and the polysensory zone (PZ) in the precentral gyrus, evokes a specific set of movements. In one interpretation, these movements correspond to those typically used to defend the body from objects that are near, approaching, or touching the skin. The present study examined the movements evoked by a puff of air aimed at various locations on the face and body of fascicularis monkeys to compare them to the movements evoked by stimulation of VIP and PZ. The air-puff-evoked movements included a movement of the eyes from any initial position toward a central region and a variety of stereotyped facial, shoulder, head, and arm movements. These movements were similar to those reported on stimulation of VIP and PZ. One difference between the air-puff-evoked movements and those evoked by stimulation of VIP and PZ is that the air puff evoked an initial startle response (a bilaterally symmetric spike in muscle activity) followed by a more sustained, lateralized response, specific to the site of the air puff. In contrast, stimulation of VIP and PZ evoked mainly a sustained, lateralized response, specific to the site of the receptive fields of the stimulated neurons. We speculate that VIP and PZ may contribute to the control of defensive movements, but that they may emphasize the more spatially specific reactions that occur after startle.

Animals↗
PubMed2006

An optimization principle for determining movement duration.

Movement duration is an integral component of motor control, but nearly all extant optimization models of motor planning prefix duration instead of explaining it. Here we propose a new optimization principle that predicts movement duration. The model assumes that the brain attempts to minimize movement duration under the constraint of meeting an accuracy criterion. The criterion is task and context dependent but is fixed for a given task and context. The model determines a unique duration as a trade-off between speed (time optimality) and accuracy (acceptable endpoint scatter). We analyzed the model for a linear motor plant, and obtained a closed-form equation for determining movement duration. By solving the equation numerically with specific plant parameters for the eye and arm, we found that the model can reproduce saccade duration as a function of amplitude (the main sequence), and arm-movement duration as a function of the ratio of target distance to size (Fitts's law). In addition, it explains the dependency of peak saccadic speed on amplitude and the dependency of saccadic duration on initial eye position. Furthermore, for arm movements, the model predicts a scaling relationship between peak velocity and distance and a reduction in movement duration with a moderate increase in viscosity. Finally, for a linear plant, our model predicts a neural control signal identical to that of the minimum-variance model set to the same movement duration. This control signal is a smooth function of time (except at the endpoint), in contrast to the discontinuous bang-bang control found in the time-optimal control literature. We suggest that one aspect of movement planning, as revealed by movement duration, may be to assign an endpoint accuracy criterion for a given task and context.

Algorithms↗