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At least 289 records · Page 16Linked to original sources
PubMed1982

On movement-related forebrain and midbrain multiple unit activity in rats. II. Some constraints on movement.

In 18 rats multiple unit activity was recorded simultaneously from ventral forebrain, dorsal midbrain, and other areas, with continuous monitoring by sensitive head movement and body movement recorders, along with careful observations or ongoing behaviors. In the preceding article of this series, we reported significant covariations between neural activity and motoric activity in forebrain and midbrain areas in the rat. In the present article, we pointed out exceptions to this general finding. The data that we have presented in this paper refute the principle of invariably tight coupling between motoric and midbrain reticular activity as stated by Schwartzbaum (1975). Our data are clearly opposed to his view that movement patterns set the range within which midbrain neural activity varies, and opposed to his conclusion that midbrain activity conforms to the immediate properties of behavior apart from conditions giving rise to the behavior. In reviewing our data, the probable role of midbrain mechanisms in preparatory phases of movement was discussed.

Acoustic Stimulation↗
PubMed1986

Coordination of arm movements in three-dimensional space. Sensorimotor mapping during drawing movement.

In this paper data are presented concerning the motion of limb segments during drawing movements executed in different planes in free space. The technique used allows the determination of the wrist and elbow positions in space as well as the measurement of the elbow angle of extension. Other kinematic variables are determined trigonometrically. Elbow and shoulder torque is also calculated. For circles and ellipses, it was found that the motion at the wrist is sinusoidal in two orthogonal directions in the plane of motion. Angular motion, when described by a set of angles previously identified psychophysically as constituting an appropriate coordinate system, is also sinusoidal. Although the number of degrees of freedom of the arm affords many possible ways of performing the task, there is a fixed phase relation between the angles of elevation of the upper arm and forearm for naturally executed movements in all planes of space. Also, the phase of the yaw angles of the upper arm and forearm relative to the angles of elevation are related to the plane of motion and to the slant of ellipses in a fixed manner. There is a simple mapping between angular motion and intended wrist trajectory. Because this mapping is not valid for all planes of space, the actual trajectory can deviate from the intended one. However, the subject has no cognizance of the distortion. The calculated torque deviates substantially from sinusoidal and does change significantly when the same movement is executed in different planes. Results of simulations and mathematical analysis indicate that the fixed phase relationship between angles of elevation leads to a minimal distortion from sinusoidal motion at the wrist in an average sense and that the characteristic distortions observed in the sagittal plane result inevitably from this constraint on the phase relations. The results support the assumption that the topology of the sensorimotor map used for the production of the movement and for its perception is the same. The problem of invariant relationships between kinematic parameters is discussed and the suggestion is made that they represent a general constraint, leading through learning and practice to an optimal solution in an average sense.

Arm↗
PubMed1982

Effects of intravenous glucose injections on human fetal breathing movements and gross fetal body movements at 38 to 40 weeks' gestational age.

Fetal breathing movements and gross fetal body movements were studied subsequent to the intravenous injection of either 25 gm of glucose or an equal volume of normal saline solution in 10 healthy women with uncomplicated pregnancies at 38 to 40 weeks' gestation. The incidence of fetal breathing increased from 17.5% during the control period to 54.9% after glucose injection. Neither glucose nor saline solution had any effect on the incidence of gross fetal body movements. All fetuses made some breathing movements during any 15-minute interval between 30 and 75 minutes after glucose injection. These data suggest a useful strategy for clinical measurement of fetal breathing activity near term.

Apgar Score↗
PubMed1999

Simulated movement termination for balance recovery: can movement strategies be sought to maintain stability in the presence of slipping or forced sliding?

Slipping during various kinds of movement often leads to potentially dangerous incidents of falling. The purpose of this study was to determine whether there was evidence to support the theory that movement strategies could be used by individuals to regain stability during an episode of slipping and whether forced sliding from a moving platform accurately simulated the effect of slipping on stability and balance. A single-link-plus-foot biomechanical model was used to mathematically simulate base of support (BOS) translation and body segment rotation during movement termination in sagittal plane. An optimization routine was used to determine region of stability [defined at given COM locations as the feasible range of horizontal velocities of the center of mass (COM) of human subject that can be reduced to zero with respect to the BOS while still allowing the COM to traverse within the BOS limits]. We found some 30% overlap in the region of stability for slipping and non-slipping conditions. This finding supports the theory that movement strategies can be sought for restoring stability and balance even if slipping unexpectedly occurs. We also found that forced sliding produces effects on stability that are similar to those of slipping, indicated by over 50% overlap in the regions of stability for the two conditions. In addition, forced sliding has distinctive effects on stability, including a "shift" of the region of stability extended beyond the BOS in the direction of sliding. These findings may provide quantifiable guidance for balance training aimed at reducing fall incidents under uncertain floor surface conditions.

Accidental Falls↗
PubMed1998

Cortical activation during fast repetitive finger movements in humans: steady-state movement-related magnetic fields and their cortical generators.

OBJECTIVE: To study the cortical physiology of fast repetitive finger movements. METHODS: We recorded steady-state movement-related magnetic fields (ssMRMFs) associated with self-paced, repetitive, 2-Hz finger movements in a 122-channel whole-head magnetometer. The ssMRMF generators were determined by equivalent current dipole (ECD) modeling and co-registered with anatomical magnetic resonance images (MRIs). RESULTS: Two major ssMRMF components occurred in proximity to EMG onset: a motor field (MF) peaking at 37+/-11 ms after EMG onset, and a postmovement field (post-MF), with inverse polarity, peaking at 102+/-13 ms after EMG onset. The ECD for the MF was located in the primary motor cortex (M1), and the ECD for the post-MF in the primary somatosensory cortex (S1). The MF was probably closely related to the generation of corticospinal volleys, whereas the post-MF most likely represented reafferent feedback processing. CONCLUSIONS: The present data offer further evidence that the main phasic changes of cortical activity occur in direct proximity to repetitive EMG bursts in the contralateral M1 and S1. They complement previous electroencephalography (EEG) findings on steady-state movement-related cortical potentials (ssMRCPs) by providing more precise anatomical information, and thereby enhance the potential value of ssMRCPs and ssMRMFs for studying human sensorimotor cortex activation non-invasively and with high temporal resolution.

Adult↗
PubMed2000

Movement-related potentials in the human spinal cord preceding toe movement.

OBJECTIVES: A method by which potentials related to voluntary movement can be recorded noninvasively from the human spinal cord is presented. METHODS: A novel signal processing technique performed on signals recorded by surface electrodes placed over the spinal column was used to filter time-locked back muscle noise, so that the only remaining signals were the spinal movement-related potentials from the brain to the limbs and vice versa. RESULTS: The signals obtained from 7 subjects using this technique are shown and temporally compared with movement-related cortical potentials (MRCP) and muscle electromyogram. It is demonstrated that the spinal signal starts approximately 600 ms before the actual movement, and that some features of this signal correspond to changes in cortical potentials. CONCLUSIONS: These findings imply that the spinal cord is not a simple command-carrying medium from the brain to the limbs, and implies that some computational activities take place at the spinal cord level.

Adult↗
PubMed2004

Eyelid movements measured by Nightcap predict slow eye movements during quiet wakefulness in humans.

A precipitous decline in eyelid movements (ELMs) has been shown to be a highly reliable indicator of sleep onset. While ELMs correlate well with eye movements during waking and rapid eye movement (REM) sleep, the eye sensor remains silent during the period of slow eye movements (SEMs) typical of sleep onset. If the ELM density (e.g. ELMs per minute) dropped simultaneously with the appearance of SEMs prior to sleep onset, it could be a promising tool for identifying decreases in alertness prior to overt sleep onset. The present study was designed to determine whether the presence of SEMs in the transitional period preceding stage 1 sleep is reflected in decreases in ELM density. ELM densities were computed for 2.5-s epochs with and without SEMs, as well as for 15-s epochs. Decreases in ELM density not only were an excellent correlate of the appearance of SEMs during wakefulness with closed eyes, but also a good predictor of their occurrence (c. 82% accuracy) at a time resolution of 2.5 s. Based on these results, we conclude that ELM density reliably predicts moderate changes in the level of alertness during quiet wakefulness.

Adult↗
PubMed1991

Induced rotary movement during eye movements: displays with unequal spacing of pattern.

In my previous (Reinhardt-Rutland, 1982) study, I suggested that eye movements enhance induced rotary movement. However, low salience of absolute displacement might also explain the results, as displays were covered with large numbers of equally spaced radial pattern elements. To test these competing hypotheses in the present study, I used an unequally spaced pattern in two displays. Common to each display was an annulus: In one display, the common annulus surrounded a disk, and in the other display the common annulus was surrounded by another annulus. In any trial, one component rotated and the other was stationary while for 40 s the subject's eyes followed a circular path concentric with the display; subjects timed those occasions when perceived stronger rotation resided in the common annulus. Despite an unequally spaced pattern, absolute displacement had a barely significant effect. Instead, perceived stronger rotation mostly resided in a display's more central component. I concluded therefore that eye movements enhance induced rotary movement.

Adult↗
PubMed1998

Reliance on external cues for movement initiation in Parkinson's disease. Evidence from movement-related potentials.

The aim of this study was to investigate the neurophysiological mechanisms underlying Parkinson's disease patients' increased reliance on external cues for the initiation of movement. Lateralized movement-related cortical potentials were recorded in a noise-compatibility task with seven patients and seven age-matched control subjects. In this two-choice task, visual stimuli containing incompatible target and distractor elements, which simultaneously instructed for responses from both hands, initially caused activation of the motor cortex controlling the wrong response hand. The incorrect response activation was of higher amplitude in patients than in control subjects, causing a longer response delay relative to response times when target and distractors instructed the same hand. In addition, hand-specific motor cortex activation started earlier in patients than in control subjects. These results indicate that visual stimuli exerted an earlier and stronger influence on movement initiation in patients than in control subjects. We hypothesize that information from sensory stimuli relevant for the generation of a response can have rapid access to motor structures in Parkinson's disease patients, thereby facilitating the initiation of movement. The findings may reflect a compensatory mechanism, but could also be related to excitability changes in the motor cortex intrinsic to the pathophysiology of Parkinson's disease.

Aged↗
PubMed2002

Experimental tooth movement under light orthodontic forces: rates of tooth movement and changes of the periodontium.

AIM: To investigate light forces for experimental tooth movement. METHOD: Light orthodontic forces of 1.2, 3.6, 6.5, and 10 g force (gf) were applied for 14 days to move rat molars, and the effects of the forces on the rate of tooth movement and changes of the periodontium were examined. RESULTS: In the early period, despite the different levels of force used in each group, there were no significant differences in tooth displacement. From hour 56 to day 14, the tooth displacement in the 1.2 gf group was significantly smaller than that in the other groups and the rate was nearly constant. The rates of tooth displacement in the 3.6, 6.5, and 10 gf groups fluctuated repeatedly, while the orthodontic forces gradually decreased. CONCLUSION: Experimental tooth movement in rats, tipping without friction under light forces, were either constant or fluctuated in cycles of several days' duration. This is in contradiction to the three-phases-theory of tooth movement described in previous investigations using heavy forces.

Alveolar Process↗
PubMed2000

P42 movement protein of Beet necrotic yellow vein virus is targeted by the movement proteins P13 and P15 to punctate bodies associated with plasmodesmata.

Cell-to-cell movement of Beet necrotic yellow vein virus (BNYVV) is driven by a set of three movement proteins--P42, P13, and P15--organized into a triple gene block (TGB) on viral RNA 2. The first TGB protein, P42, has been fused to the green fluorescent protein (GFP) and fusion proteins between P42 and GFP were expressed from a BNYVV RNA 3-based replicon during virus infection. GFP-P42, in which the GFP was fused to the P42 N terminus, could drive viral cell-to-cell movement when the copy of the P42 gene on RNA 2 was disabled but the C-terminal fusion P42-GFP could not. Confocal microscopy of epidermal cells of Chenopodium quinoa near the leading edge of the infection revealed that GFP-P42 localized to punctate bodies apposed to the cell wall whereas free GFP, expressed from the replicon, was distributed uniformly throughout the cytoplasm. The punctate bodies sometimes appeared to traverse the cell wall or to form pairs of disconnected bodies on each side. The punctate bodies co-localized with callose, indicating that they are associated with plasmodesmata-rich regions such as pit fields. Point mutations in P42 that inhibited its ability to drive cell-to-cell movement also inhibited GFP-P42 punctate body formation. GFP-P42 punctate body formation was dependent on expression of P13 and P15 during the infection, indicating that these proteins act together or sequentially to localize P42 to the plasmodesmata.

Amino Acid Sequence↗
PubMed1998

Cortical activation during fast repetitive finger movements in humans: dipole sources of steady-state movement-related cortical potentials.

Fast repetitive finger movements are associated with characteristic EEG patterns described in humans as steady-state movement-related cortical potentials (ssMRCPs). The objective of the present study was to determine the electrical generators of ssMRCPs (movement rate, 2 Hz) by dipole modelling. The generators for the initial ssMRCP phase (peak approximately 60 msec before EMG onset) were located in the central region bilaterally, with largely radial orientation, consistent with activation of the crown of the precentral gyrus. The generator of the next phase (peak approximately 10 msec after EMG onset) was located in the contralateral central region with tangential posterior orientation, consistent with activation of the anterior wall of the central sulcus. The postmovement phase (peak approximately 95 msec after EMG onset) was explained by another source in the contralateral central region with tangential anterior orientation, consistent with activation of the posterior wall of the central sulcus. This pattern probably corresponds to a sequence of activation of the bilateral dorsal premotor cortex, contralateral primary motor, and primary somatosensory cortex that takes place within approximately 200 msec around EMG onset. Steady-state movement-related cortical potentials in combination with dipole modelling provide a novel, noninvasive approach to assessing changes of human cortical premotor, motor, and somatosensory activation in the millisecond range.

Adult↗
PubMed2005

Cucumber mosaic virus 2a polymerase and 3a movement proteins independently affect both virus movement and the timing of symptom development in zucchini squash.

The basis for differences in the timing of systemic symptom elicitation in zucchini squash between a pepper strain of Cucumber mosaic virus (Pf-CMV) and a cucurbit strain (Fny-CMV) was analysed. The difference in timing of appearance of systemic symptoms was shown to map to both RNA 2 and RNA 3 of Pf-CMV, with pseudorecombinant viruses containing either RNA 2 or RNA 3 from Pf-CMV showing an intermediate rate of systemic symptom development compared with those containing both or neither Pf-CMV RNAs. Symptom phenotype was shown to map to two single-nucleotide changes, both in codons for Ile at aa 267 and 168 (in Fny-CMV RNAs 2 and 3, respectively) to Thr (in Pf-CMV RNAs 2 and 3). The differential rate of symptom development was shown to be due to differences in the rates of cell-to-cell movement in the inoculated cotyledons, as well as differences in the rate of egress of the virus from the inoculated leaves. These data indicate that both the CMV 3a movement protein and the CMV 2a polymerase protein affect the rate of movement of CMV in zucchini squash and that these two proteins function independently of each other in their interactions with the host, facilitating virus movement.

Cucumovirus↗
PubMed1984

Relation between the specific H reflex facilitation preceding a voluntary movement and movement parameters in man.

In a reaction-time situation, the monosynaptic spinal reflex (H reflex) is facilitated before the onset of an electromyographic (e.m.g.) response. The aim of the present investigation was to study aspects of this facilitation. Human subjects were required to perform isometric plantarflexions of the foot in response to a visual stimulus. The movement was always on the same side in the simple reaction-time situation, and randomly with the right or left foot in the choice reaction-time situation. Stimuli to evoke H reflexes were applied bilaterally 40-400 ms after the onset of the visual stimulus. Pre-motor time, i.e. the interval between the onset of the visual stimulus and the e.m.g. response, and reaction time, i.e. the interval between the onset of the visual stimulus and the response on the torque recording, were computed. In both reaction-time situations, there was a significant facilitation of the ipsilateral H reflex 100-160 ms before e.m.g. onset and, in some subjects, a small facilitation of the contralateral H reflex. The specific facilitation, i.e. the difference between the facilitation on the ipsi- and contralateral side relative to the movement, was not significantly different on the right and left side. Pre-motor time was divided into the interval from the light onset until the onset of the specific facilitation, and the interval from the onset of the facilitation until the onset of the voluntary response. Both intervals increased, and the slope and the amplitude of the facilitation decreased with increasing pre-motor time and reaction time. The specificity of the H reflex facilitation in a choice reaction-time situation implies that the interval from light onset until the onset of the facilitation includes stimulus identification and response selection, and the interval from the onset of the facilitation until the e.m.g. response preparation of the motor system for the required movement. The present results suggest that the specific facilitation of the H reflex before a movement is caused by removal of presynaptic inhibition at I a terminals or by activation of interneurones intercalated in polysynaptic components of the H reflex rather than by a subthreshold activation of motoneurones.

Action Potentials↗
PubMed2006

Encoding of movement dynamics by Purkinje cell simple spike activity during fast arm movements under resistive and assistive force fields.

It is controversial whether simple-spike activity of cerebellar Purkinje cells during arm movements encodes movement kinematics like velocity or dynamics like muscle activities. To examine this issue, we trained monkeys to flex or extend the elbow by 45 degrees in 400 ms under resistive and assistive force fields but without altering kinematics. During the task movements after training, simple-spike discharges were recorded in the intermediate part of the cerebellum in lobules V-VI, and electromyographic activity was recorded from arm muscles. Velocity profiles (kinematics) in the two force fields were almost identical to each other, whereas not only the electromyographic activities (dynamics) but also simple-spike activities in many Purkinje cells differed distinctly depending on the type of force field. Simple-spike activities encoded much larger mutual information with the type of force field than that with the residual small difference in the height of peak velocity. The difference in simple-spike activities averaged over the recorded Purkinje-cells increased approximately 40 ms before the appearance of the difference in electromyographic activities between the two force fields, suggesting that the difference of simple-spike activities could be the origin of the difference of muscle activities. Simple-spike activity of many Purkinje cells correlated with electromyographic activity with a lead of approximately 80 ms, and these neurons had little overlap with another group of neurons the simple-spike activity of which correlated with velocity profiles. These results show that simple-spike activity of at least a group of Purkinje cells in the intermediate part of cerebellar lobules V-VI encodes movement dynamics.

Animals↗
PubMed1991

Analysis of vertebrate eye movements following intravitreal drug injections. IV. Drug-induced eye movements are unyoked in the turtle.

1. Eye movements of awake turtles were measured from both eyes simultaneously using two search-coil contact lenses. Optokinetic nystagmus (OKN) was evoked by full field patterns moving horizontally at different stimulus velocities. Intravitreal injections of either bicuculline or 2-amino-4-phosphonobutyrate (APB) were then made into one eye, after which eye movements were again recorded under similar stimulus conditions. Several days later, eye movements were again recorded and recovery was observed. 2. The effects of these two synaptic drugs on the optokinetic responses of the injected eye were similar to those previously reported in turtles, rabbits, and decorticate cats. APB, which blocks the retinal ON pathways, completely blocked visually evoked responses to any stimulus direction or velocity presented to the injected eye. On the other hand, the uninjected eye was still responsive to optokinetic stimuli. This difference between the eyes is consistent with the nonconjugate nature of OKN in the turtle. 3. After bicuclline application, the injected eye displayed a spontaneous nystagmus with its slow phase in the temporal-to-nasal direction. The movements of the injected eye were independent of stimulus direction or a range of stimulus velocities. During that effect, the eye contralateral to the injection still responded to visual stimuli in a direction- and velocity-dependent manner. For example, if the uninjected eye was exposed to optokinetic stimuli moving temporal-to-nasal, both eyes would then move in their respective temporal-to-nasal directions. This nonconjugate ocular behavior is similar to that seen when each eye of a normal turtle was exposed to its temporal-to-nasal stimulus.(ABSTRACT TRUNCATED AT 250 WORDS)

Aminobutyrates↗
PubMed1989

[Study on changes of mandibular movement by aging. 1. Analysis of sagittal movements].

It is known that the temporomandibular joint changes with age. However, it isn't clarified yet how these changes affect mandibular movements. Therefore, I investigated the changes which occur in mandibular movement with aging. This study details 62 cases whose age ranged from 20 to 79 years, and whose dentition was either complete or nearly so, and whose intercuspal position was firm. First, I investigated the path of protrusive movement at representative points on the mandible, such as incisor, canine, first molar, second molar, the condylar center and the kinematic axis point. Results were as follows: 1) Data obtained from the 20 to 29 year old age group differed little from the results of previous investigations, 2) The sagittal inclination of the condylar path became less acute in subjects 60 years and over than in the younger subjects. Second, I evaluated the vertical mobility of the condyle by the gap between opening path and closing path of the condyle in sagittal border movement and the location of the kinematic axis point. The results showed that the gap between the two paths of the condylar center was slightly larger and the kinematic axis point was tended to locate more anteriorly in subjects 50 years and up than in the others.

Adult↗
PubMed1979

Effects on fetal breathing movements of maternal challenges. Cross-over study on dynamic work, static work, passive movements, hyperventilation and hyperoxygenation.

Ten women in the last trimester of a normal pregnancy were subjected to five different loads in a cross-over study. Fetal breathing movements (FBM), fetal heart rate (FHR), maternal heart rate (MHR), and mean arterial pressure (MAP), maternal transcutaneously measured pO2 (Tc-pO2), and the energy supply to the Tc-pO2 electrode were recorded continuously before, during, and after the load. Maternal capillary pH and pCO2 were measured at three representative time points. The immediate responses of the incidence of FBM to the different challenges were: increase after dynamic work (bicycle test); no change after static work (isometric muscle contraction) and passive movements; decrease after hyperventilation and hyperoxygenation. FHR was unaffected by all challenges. The FBM incidence varied in parallel with pCO2 after dynamic work and hyperventilation and inversely with the Tc-pO2 rise caused by hyperoxygenation. Maternal pH was increased after passive movements (no change in FBM) and after hyperventilation (decreased incidence of FBM), FBM seem to be more sensitive to environmental changes than is the FHR. Mechanical stimuli to the uterus were not responsible for the augmentation of FMB seen after the bicycle test. The present observations reveal the multifactorial nature of the regulation of FBM, and support the role of CO2 as a major stimulator of breathing movements also in prenatal life.

Adult↗