Movements In Healthy Subjects Research Articles

The trunk as a part of the kinematic chain for reaching movements in healthy subjects and hemiparetic patients

The aims of this study were first to further assess the role of the 3D trunk angular rotations as part of the kinematic chain for seated-reaching movements within arm's length in a large 3D workspace in healthy subjects and second, to assess if these degrees of freedom participate in the compensatory strategy in hemiparetic patients. Ten healthy subjects, eight patients with right, and eight patients with left hemiparesis following stroke were included. They performed seated reaching movements at a comfortable speed to nine targets positioned in a large 3D workspace within arm's length. An electromagnetic system was used to record kinematics of the trunk and hand. Trunk flexion, lateral flexion and torsion were analyzed as a function of target direction, distance and height. In both healthy subjects and patients, all three trunk rotations participated in the reaching movement (except for near targets in healthy subjects). Trunk flexion was greater in patients but followed a similar pattern to healthy subjects. Trunk torsion was more influenced by target distance in healthy subjects while in patients it was greatly influenced by direction. Trunk lateral flexion was similar between groups. Comparing the two patient groups, there was greater flexion to the external targets in the RHD group and different strategies in the use of torsion between groups. 3D trunk rotations thus seem to be tuned to the distance and direction of the target in the workspace in both healthy subjects and stroke patients for reaching movements within arm's length.

Colonic movements in healthy subjects as monitored by a Magnet Tracking System

The Magnet Tracking System (MTS) is a minimally-invasive technique of continuous evaluation of gastrointestinal motility. In this study, MTS was used to analyse colonic propulsive dynamics and compare the transit of a magnetic pill with that of standard radio-opaque markers. MTS monitors the progress in real time of a magnetic pill through the gut. Ten men and 10 women with regular daily bowel movements swallowed this pill and 10 radio-opaque markers at 8 pm. Five hours of recordings were conducted during 2 following mornings. Origin, direction, amplitude and velocity of movements were analysed relative to space-time plots of the pill trajectory. Abdominal radiographs were taken to compare the progress of both pill and markers. The magnetic pill lay idle for 90% of its sojourn in the colon; its total retrograde displacement accounted for only 20% of its overall movement. Analysis of these movements showed a bimodal distribution of velocities: around 1.5 and 50 cm min(-1), the latter being responsible for 2/3 of distance traversed. There were more movements overall and more mass movements in males. Net hourly forward progress was greater in the left than right colon, and greater in males. The position of the magnetic pill correlated well with the advancement of markers. MTS showed patterns and propulsion dynamics of colonic segments with as yet unmet precision. Detailed analysis of slow and fast patterns of colonic progress makes it possible to specify the motility of colonic segments, and any variability in gender. Such analysis opens up promising avenues in studies of motility disorders.

Neural substrates of low‐frequency repetitive transcranial magnetic stimulation during movement in healthy subjects and acute stroke patients. A PET study

The aim of the study was to investigate, with an rTMS/PET protocol, the after-effects induced by 1-Hz repetitive transcranial magnetic stimulation (rTMS) in the regional cerebral blood flow (rCBF) of the primary motor cortex (M1) contralateral to that stimulated during a movement. Eighteen healthy subjects underwent a baseline PET scan followed, in randomized order, by a session of Real/Sham low-frequency (1 Hz) subthreshold rTMS over the right M1 for 23 min. The site of stimulation was fMRI-guided. After each rTMS session (real or sham), subjects underwent behavioral hand motor tests and four PET scans. During the first two scans, ten subjects (RH group) moved the right hand ipsilateral to the stimulated site and eight subjects (LH group) moved the left contralateral hand. All remained still during the last two scans (rest). Two stroke patients underwent the same protocol with rTMS applied on contralesional M1. Compared with Sham-rTMS, Real-rTMS over the right M1 was followed by a significant increase of rCBF during right hand movement in left S1M1, without any significant change in motor performance. The effect lasted less than 1 h. The same rTMS-induced S1M1 overactivation was observed in the two stroke patients. Commissural connectivity between right dorsal premotor cortex and left M1 after real-rTMS was observed with a psychophysiological interaction analysis in healthy subjects. No major changes were found for the left hand. These results give further arguments in favor of a plastic commissural connectivity between M1 both in healthy subjects and in stroke patients, and reinforce the potential for therapeutic benefit of low-frequency rTMS in stroke rehabilitation.

Effect of electroacupuncture on zusanli (stomach-36) in post prandial antropyloric movement

Objective: Acupuncture is used to treat gastrointestinal discomfort and improve gastric movement, but how acupuncture stimulates human gastric movement has not been studied. We examined the influence of electroacupuncture on post prandial gastric movement in healthy subjects by ultrasonographically observing the gastric antrum. We measured electrogastrography (EGG) simultaneously with ultrasonography, and studied the relationship between EGG and actual gastric contraction. Method: Antropyloric movement was recorded in a control group of 7 healthy subjects and in an electroacupuncture group of 7 healthy subjects.

Effects of intermittent theta‐burst stimulation on practice‐related changes in fast finger movements in healthy subjects

In this paper we investigated the effects of intermittent theta-burst stimulation (iTBS) applied to the primary motor cortex on practice-related changes in motor performance. Seventeen healthy subjects underwent two experimental sessions, one testing real iTBS and the other testing sham iTBS. Before and after both iTBS sessions, the subjects practiced fast right index-finger abductions for a few minutes. As measures of cortical excitability we calculated resting motor threshold and motor-evoked potential amplitude. As measures of practice-related changes we evaluated the mean movement amplitude, peak velocity and peak acceleration values for each block. When subjects practiced the movement task, the three variables measuring practice-related changes improved to a similar extent during real and sham iTBS whereas cortical excitability increased only during real iTBS. In a further group of five healthy subjects we investigated the effect of real and sham iTBS on changes in motor performance after a longer task practice and found no significant changes in motor performance and retention after real and sham iTBS. From our results overall we conclude that in healthy subjects iTBS applied to the primary motor cortex leaves practice-related changes in an index finger abduction task unaffected. We suggest that iTBS delivered over the primary motor cortex is insufficient to alter motor performance because early motor learning probably engages a wide cortical and subcortical network.

Novel 3-D video for quantification of facial movement

To evaluate a novel 3-D geometry video acquisition system (3-D VAS) for quantifying facial movement. Ten normal subjects and four patients with facial paralysis underwent recording of facial movement during three facial expressions. Facial feature points of interest were digitally marked on selected images. The maximum 3-D displacement of the brow and oral commissure and palpebral fissure width were determined. Test-retest reliability using the 3-D VAS in normal subjects was high (Spearman correlation coefficients 0.661-0.830, P < 0.05). The predicted ratio of left to right facial measurements was 1.00 in normal subjects, and measured mean ratios were 1.05 (brow excursion), 1.01 (palpebral fissure width), and 1.03 (oral commissure excursion), respectively, matching the prediction. The 3-D VAS reliably quantified facial movement on both sides in patients with facial paralysis. The novel 3-D VAS can accurately and reliably quantify facial movement in healthy subjects. It is promising as a clinical tool to quantify facial movement in patients with facial paralysis.

Extraocular muscle deformation assessed by motion-encoded MRI during eye movement in healthy subjects

Conventional magnetic resonance imaging (MRI) is useful for assessing morphological changes but not for assessing deformations inside homogeneous structures (M. D. Abràmoff, A. P. Van Gils, G. H. Jansen, & M. P. Mourits, 2000). Since no intrinsic contrast can be imaged for distinguishing heterogeneous patterns of muscle contraction, morphological changes along the length of the extraocular muscles (EOMs) are not macroscopically detectable. However, an imaging method that is able to directly encode motion could give evidence about the dynamics of the inhomogeneous deformation of the EOMs. Thus, we developed a method for acquiring motion-encoded MRI images of the EOMs during eye movements. Seven healthy subjects gazed at a horizontal sinusoidally oscillating target. A small surface coil was placed in front of the right orbit. The contracting and relaxing horizontal rectus muscles and the noncontracting optic nerve were reliably tracked. The differential contractility of the EOMs could be distinguished from the third time frame on (=140 ms from the beginning of the right to left eye movement lasting 1 s). The muscle belly of the contracting medial rectus muscle could be distinguished from the posterior and the anterior segment from the sixth time frame on (=350 ms). In conclusion, motion-encoded MRI resolved the heterogeneous contraction of moving EOM segments in healthy subjects without using physical markers.

A Life Span Study of Exploratory Eye Movements in Healthy Subjects: Gender Differences and Affective Influences

To evaluate age and gender differences as well as effects of affection, we examined exploratory eye movements. Exploratory eye movements were recorded in healthy subjects (57 women and 57 men) ranging from 9 to 74 years. All subjects were divided into three groups as pre puberty, young, and older adults to study the influences of age and gonadal hormones. Exploratory eye movements were analyzed for total eye scanning length (TESL), and total numbers of gaze points (TNGP) as subjects viewed neutral or affectively charged pictures. TESL and TNGP in older adults were significantly larger than that in both pre puberty and young adults for crying babies. TESL and TNGP in pre puberty were significantly smaller than that in both young and older adults for circles. TESL and TNGP in pre puberty were significantly smaller than that in older adults for smiling babies. Pre puberty and young adult of both genders for crying babies showed significantly shorter TESL than for when smiling babies. When viewing circles, young adult women had shorter TESL than men. TNGP in young adult women was smaller than in men for circles or crying babies. TNGP of young adult women in the visual right field was significantly smaller than in men. TNGP for crying babies was significantly smaller than that for smiling babies in young adults of both genders for the left field. Exploratory eye movements thus are a useful marker of visual cognitive function. Gender differences were limited to younger adults, suggesting influences of gonadal hormones.

Clinical Assessment of Motor Function: A Processes Oriented Instrument Based on a Speed‐Accuracy Trade‐Off Paradigm

In this study, we developed a digitizing tablet-based instrument for the clinical assessment of human voluntary movements targeting motor processes of planning, programming and execution. The tool was used to investigate an adaptation of Fitts' reciprocal tapping task [10], comprising four conditions, each of them modulated by three indices of difficulty related to the amplitude of movement required. Temporal, spatial and sequential constraints underlying the various conditions allowed the intricate motor processes to be dissociated. Data obtained from a group of elderly healthy subjects (N = 50) were in agreement with the literature on motor control, in the temporal and spatial domains. Speed constraints generated gains in the temporal domain and costs in the spatial one, while spatial constraints generated gain in the spatial domain and costs in the temporal one; finally, sequential constraints revealed the integrative nature of the cognitive operations involved in motor production. This versatile instrument proved capable of providing quantitative, accurate and sensitive measures of the various processes sustaining voluntary movement in healthy subjects. Altogether, analyses performed in this study generated a theoretical framework and reference data which could be used in the future for the clinical assessment of patients with various movement disorders, in particular Parkinson’s disease.

Reliability of arthrometric measurement of shoulder lateral rotation movement in healthy subjects

Numerous pathologic conditions of the shoulder result in loss of range of motion with lateral rotation being one of the most affected movements. Therefore, it is essential to know the reliability of the methods to measure this motion from a treatment evaluation perspective. The purpose of this study was to examine the reliability of the shoulder lateral rotation movement measured by an arthrometric method. Fifteen healthy subjects participated in the study. The passive range of motion in lateral rotation of the shoulder was measured with an arthrometric method for three positions of shoulder abduction and with three loads. Two evaluators took each measurement on two separate occasions. The reliability was good at 60° and 90° abduction with dependability indexes (ϕ) ranging from 0.77 to 0.87 and SEMs lower than 5°. The reliability at 25° abduction was lower with dependability indexes (ϕ) ranging from 0.52 to 0.66 and SEMs of 7° or 8°. Reliability was highest with the heaviest load reaching 0.66, 0.84, and 0.87 for the 25°, 60°, 90° abduction angles, respectively. In all conditions of measurement, differences between intratester and intertester reliability were minimal. Reliability of the shoulder lateral rotation measured by arthrometry was dependent on angle of abduction and load used to move the shoulder. Further studies are needed to confirm these findings in individuals with impaired shoulders.

Event-related beta EEG-changes during passive and attempted foot movements in paraplegic patients

A number of electroencephalographic (EEG) studies report on motor event-related desynchronization and synchronization (ERD/ERS) in the beta band, i.e. a decrease and increase of spectral amplitudes of central beta rhythms in the range from 13 to 35 Hz. Following an ERD that occurs shortly before and during the movement, bursts of beta oscillations (beta ERS) appear within a 1-s interval after movement offset. Such a post-movement beta ERS has been reported after voluntary hand movements, passive movements, movement imagination, and also after movements induced by functional electrical stimulation. The present study compares ERD/ERS patterns in paraplegic patients (suffering from a complete spinal cord injury) and healthy subjects during attempted (active) and passive foot movements. The aim of this work is to address the question, whether patients do have the same focal beta ERD/ERS pattern during attempted foot movement as healthy subjects do. The results showed midcentral-focused beta ERD/ERS patterns during passive, active, and imagined foot movements in healthy subjects. This is in contrast to a diffuse and broad distributed ERD/ERS pattern during attempted foot movements in patients. Only one patient showed a similar ERD/ERS pattern. Furthermore, no significant ERD/ERS patterns during passive foot movement in the group of the paraplegics could be found.

The Berlin brain-computer interface: EEG-based communication without subject training

The Berlin Brain-Computer Interface (BBCI) project develops a noninvasive BCI system whose key features are 1) the use of well-established motor competences as control paradigms, 2) high-dimensional features from 128-channel electroencephalogram (EEG), and 3) advanced machine learning techniques. As reported earlier, our experiments demonstrate that very high information transfer rates can be achieved using the readiness potential (RP) when predicting the laterality of upcoming left- versus right-hand movements in healthy subjects. A more recent study showed that the RP similarily accompanies phantom movements in arm amputees, but the signal strength decreases with longer loss of the limb. In a complementary approach, oscillatory features are used to discriminate imagined movements (left hand versus right hand versus foot). In a recent feedback study with six healthy subjects with no or very little experience with BCI control, three subjects achieved an information transfer rate above 35 bits per minute (bpm), and further two subjects above 24 and 15 bpm, while one subject could not achieve any BCI control. These results are encouraging for an EEG-based BCI system in untrained subjects that is independent of peripheral nervous system activity and does not rely on evoked potentials even when compared to results with very well-trained subjects operating other BCI systems.

Response to Galvanic Vestibular Stimulation in Patients with Unilateral Vestibular Loss

This study sought to characterize various responses to galvanic vestibular stimulation (GVS) by comparing GVS-induced eye movements in healthy subjects and patients with vestibular function loss. The study also aimed to estimate the clinical significance of GVS tests. Finally, an effort was made to localize the primary excitation site of stimulation in the vestibular system. Three parameters of response to GVS, spontaneous nystagmus, galvanic stimulating nystagmus (GSN), and postgalvanic stimulating nystagmus (PGSN), were evaluated in 20 normal subjects and 14 patients with complete unilateral vestibular function loss resulting from labyrinthectomy or vestibular neurectomy using a three-dimensional video-electronystagmography technique. In normal subjects, GSN was detected in all subjects and was directed toward the negative electrode. PGSN was also detected but was directed toward the opposite electrode. When the negative electrode was attached to the intact side in unilateral vestibular loss subjects, GSN was always directed toward the negative electrode and PGSN was never observed. When the negative electrode was attached to the lesion side, however, GSN was detected in only one case, and PGSN was observed and directed to the intact side in 13 patients. The response to GVS in vestibular loss patients differed from that in normal subjects, which suggests that GVS could be useful for estimating the extent of vestibular function loss. The fact that the patterns of GVS response differed so significantly suggests that the primary site of excitation is not central but is instead the peripheral vestibular organ.

Multimodal imaging of brain reorganization in motor areas of the contralesional hemisphere of well recovered patients after capsular stroke

Clinical recovery after stroke can be significant and has been attributed to plastic reorganization and recruitment of novel areas previously not engaged in a given task. As equivocal results have been reported in studies using single imaging or electrophysiological methods, here we applied an integrative multimodal approach to a group of well-recovered chronic stroke patients (n = 11; aged 50-81 years) with left capsular lesions. Focal activation during recovered hand movements was assessed with EEG spectral analysis and H2(15)O-PET with EMG monitoring, cortico-cortical connectivity with EEG coherence analysis (cortico-cortical coherence) and corticospinal connectivity with transcranial magnetic stimulation (TMS). As seen from comparisons with age-matched controls, our patients showed enhanced recruitment of the lateral premotor cortex of the lesioned hemisphere [Brodmann area (BA) 6], lateral premotor and to a lesser extent primary sensorimotor and parietal cortex of the contralesional hemisphere (CON-H; BA 4 and superior parietal lobule) and left cerebellum (patients versus controls, Z > 3.09). EEG coherence analysis showed that after stroke cortico-cortical connections were reduced in the stroke hemisphere but relatively increased in the CON-H (ANOVA, contrast analysis, P < 0.05), suggesting a shift of functional connectivity towards the CON-H. Nevertheless, fast conducting corticospinal transmission originated exclusively from the lesioned hemisphere. No direct ipsilateral motor evoked potentials (MEPs) could be elicited with TMS over the contralesional primary motor cortex (iM1) in stroke patients. We conclude that (i) effective recovery is based on enhanced utilization of ipsi- and contralesional resources, (ii) basic corticospinal commands arise from the lesioned hemisphere without recruitment of ('latent') uncrossed corticospinal tract fibres and (iii) increased contralesional activity probably facilitates control of recovered motor function by operating at a higher-order processing level, similar to but not identical with the extended network concerned with complex movements in healthy subjects.

Effects of Lithium on Saccadic Eye Movements in Healthy Subjects in a Ten-Day Double-Blind Placebo-Controlled Cross-Over Pilot Study

Although previous studies have shown that lithium modifies eye movements or psychomotor speed, no studies have ever explored the predictive saccades or memory guided saccades during lithium administration. We took the objective to determine the influence of lithium in pseudo-random, predictive or memory-guided saccades in healthy subjects with a view to detect reduced psychomotor speed, inability to anticipate incoming events, or working memory deficits. A ten day lithium-placebo randomized double-blind cross-over pilot study was carried out with 12 healthy male volunteers. The cognitive assessment included pseudo-random, predictive and memory guided saccades before and after lithium and placebo periods. A biological assay substantiated the lithium effect on TSH and thyroid hormones. There was no change in pseudo-random or memory guided saccades when comparing lithium or placebo administration. However the ratio of anticipated saccades decreased under the lithium sequence while it remained stable under placebo. Also, subjects having lithium serum levels of > 0.5 meq/l had longer latencies in anticipated saccades. The findings do not support a major effect of lithium on alertness or on working memory, although the dosage and duration of lithium was sufficient to modify TSH blood level. Nevertheless, lithium treatment was associated with decreased anticipation in predictive saccades, suggesting this could reflect a reduced ability to anticipate quick motor movements and could be related to the well-known effect of lithium as an anti-impulsive medication.

Short latency disconjugate vestibulo-ocular responses to transient stimuli in the audio frequency range

Objective: To determine whether unilateral activation of the vestibular labyrinth by brief air conducted tones can elicit disconjugate reflex eye movements in healthy subjects. Methods: 40 normal volunteers, one patient...

The timing and intensity of transcranial magnetic stimulation, and the scalp site stimulated, as variables influencing motor sequence performance in healthy subjects

The increasing therapeutic use of transcranial magnetic stimulation (TMS) in disorders of cortical excitability raises the need for reliable stimulus variables. Stimulation of cortical motor areas influences motor programming and execution. We investigated the effects of TMS delivered over various cortical motor areas during the reaction time (RT) on the execution of sequential rapid arm movements in healthy subjects. Subjects performed a five-submovement (S1-S5) motor sequence mainly involving upper limb proximal muscles. RT and movement time (MT) were measured. We delivered late (close to movement onset) and early (close to the go signal) TMS over the primary motor area (M1-FDI hot-spot for the first dorsal interosseus, M1-D hot-spot for the deltoid muscle), the premotor (PM) area, and the supplementary motor area (SMA), using subthreshold and suprathreshold intensity, single and triple pulses. The motor sequence showed a characteristic pattern of submovement duration, S2-S3-S4 being faster than S1 and S5. Late TMS prolonged RT only when high-intensity pulses were delivered over M1-FDI. Single- and triple-pulse TMS over M1-D or M1-FDI significantly prolonged MT with a dose-related effect. Suprathreshold triple-pulse TMS over the PM-but not over the SMA-also lengthened the MT but did not change RT. Early triple-pulse TMS reduced the RT independently from the stimulus intensity and scalp site. SMA and PM-but not M1-D-stimulation also reduced the MT. Single-pulse TMS over the SMA, despite being delivered through a double-cone coil, did not change RT or MT. TMS-induced changes in the kinematics of a sequential arm movement depend closely on the timing of TMS interference, the scalp site stimulated, and the intensity (and number) of stimuli delivered. Late TMS interference inhibits, whereas early interference facilitates, motor performance. The cortical motor region most sensitive to TMS-induced inhibition is that below the scalp site for M1-FDI. In contrast, TMS-induced facilitation has no strict topographic organization. Particularly for MT (although inhibitory and facilitatory effects both depend on stimulation at high intensities) intensity is less crucial than timing of interference and scalp site.

Interhemispheric Inhibition Predicts the Magnitude of Mirror Movements in Healthy Subjects

Interhemispheric Inhibition Predicts the Magnitude of Mirror Movements in Healthy Subjects

Ventilatory and Heart Rate Responses at the Onset of Chair Rotation in Man

In the present study, we attempted to confirm whether pulmonary ventilation and heart rate increased immediately after passive chair rotation in man. Inspiratory minute volume (V(I)), tidal volume (V(T)), respiratory frequency (f), and heart rate (HR) were determined by breath-by-breath and beat-by-beat techniques before, during, and after rotation for a total of 45 s. It was found that V(I) significantly increased immediately after chair rotation, but HR remained almost constant. These results suggest that the activation of horizontal semicircular canals is one causal factor of ventilatory response at the onset of exercise with rotational movement in healthy subjects, but heart rate response is not.

Is the velocity-curvature relationship disrupted in apraxic patients?

Velocity and curvature of human movements are linked by a proportionality relationship (power-law) whose origin has been attributed either to functional properties of cortical areas or to peripheral constraints. 3D movements made by apraxic patients show a time-shift between velocity and curvature which has been considered as a disruption of the power-law, supporting the central hypothesis. We analysed the power-law in 2D drawing-like movements in healthy subjects and apraxic patients (correlation and cross-correlation analyses). The power-law remained preserved in apraxic patients, suggesting that the velocity-curvature relationship is not globally disrupted and thus that the power-law cannot be only attributed to central planning mechanisms in those associative brain areas injured in apraxic patients.