Movements In Normal Subjects Research Articles

Comparing mastoid and posterior cervical muscles vibration effects on eye movement in normal subjects

Background and Aim: Vibration is a method for stimulating the vestibular system. This met­hod can unmask asymmetry between two vesti­bular systems (such as unilateral peripheral ves­tibular disorders). The occurrence of vibration-induced nystagmus (VIN) in healthy subjects can affect the diagnosis of patients with uni­lateral peripheral vestibular disorders. Thus, the evaluation of VIN in healthy subjects is critical to help the diagnosis of unilateral peripheral vestibular disorders. Methods: This study was carried out on 72 hea­lthy subjects (mean ± SD age: 27.12 ± 4.97 years) in the Auditory and Balance Clinic of Rofeideh Rehabilitation Hospital. Vibration sti­mulation with a frequency of 30 and 100 Hz was used on mastoid and posterior cervical mus­cles (PCMs) and simultaneously eye movements were recorded and analyzed using videonystag­mography. Results: The mastoid vibration with a frequ­ency of 30 and 100 Hz, respectively produced VIN in 16.67% and 27.78% of subjects and VIN observed in PCMs vibration with a frequency of 30 and 100 Hz in 4.17% and 9.72% of the subjects. Conclusion: The occurrence of VIN in healthy subjects was more probable with mastoid vib­ration in 100 Hz. In this study, VIN was pre­dominantly horizontal, its direction was toward the stimulated side, and its slow phase velocity was lower than 5 deg/s. These criteria could be used for differentiation between normal and abnormal subjects.

Variations in Respiratory Movements in Normal Subjects based on the Type of Chair Used

Background
 Sitting is the main everyday ‘activity’ of contemporary people. In In 1997, the number of hours spent weekly on computer was 5.9, whereas in 2003 it reached 14.6 per week. The latest research confirms the significant impact of the sitting posture on the respiratory system. The aim of this study to compare the respiratory chest movements based on the type of chair used.
 Aims & Objectives
 1.Comparison of respiratory amplitudes in females in chair 1 and chair 2
 2.Comparison of respiratory amplitudes in males in chair 1 and chair 2
 3.Comparison of respiratory amplitudes(in males & females) in relation with weight.
 Materials & Method
 The present study was conducted in the Research laboratory, Dept. of Physiology, RVMIMS, Laxmakkapally, Siddipet. A total of 60 subjects were selected (30 males & 30 females) between age group 17–25 years. Respiratory movements and weight were recorded. Respiratory movements were recorded using stethograph (respiratory belt) and Weight using weighing machine. The study covered respiratory chest movement assessment of the subjects in two different chairs.
 Results
 All measured values were statistically analyzed using Window Stat software. Paired t-test analysis and ANOVA has been used to find out the significant p. Amplitudes for the first chair (298.4mV) reached a higher average level than for the second one (268.9mV).The study did not show correlation between body weight and respiratory amplitudes in first chair and second chair. The comparison clearly shows a higher respiratory amplitude for females(300.3±36.9) in first chair as compared to men(296.5±43).
 Conclusion
 The study results conclude that there is a considerable change in the chest respiratory movements depending on the orientations of joints and muscle activation. Respiratory movements in chair 1 (upright position) are higher than chair 2 (slumped position). Thus an emphasis should be made on changing the seats’ physical activity and its effect on respiratory system.

Experimental assessment of cervical ranges of motion and compensatory strategies

BackgroundLiterature is still limited regarding reports of non-invasive assessment of the cervical range of motion in normal subjects. Investigations into compensatory motions, defined as the contribution of an additional direction to the required motion, are also limited.The objectives of this work were to develop and assess a reliable method for measuring the cervical range of motion in order to investigate motion and compensatory strategies.Methods and data collectionNinety-seven no neck-related pain subjects (no severe cervical pathology, 57 women, age: 28.3 ± 7.5y. old, BMI: 22.5 ± 3.2 kg/m2) underwent a non-invasive cervical range of motion assessment protocol. In-vivo head’s motion relative to the thorax was assessed through the measurement of the main angular amplitudes in the 3 directions (flexion/extension, axial rotations and lateral inclinations) and associated compensatory motions using an opto-electronic acquisition system.ResultsThe principal motion reproducibility resulted in intra-class correlation coefficients ranging from 0.81 to 0.86. The following maximum ranges of motion were found: 127.4 ± 15.1° of flexion/extension, 89.3 ± 12° of lateral inclinations and 146.4 ± 13° of axial rotations after 6 outlier exclusions. Compensatory motions highly depend on the associated principal motion: for flexion/extension: (3.5 ± 7.6;-2.1 ± 7.8°), for rotation: (25.7 ± 17.9°;0.4 ± 4.7)°, for inclination: (22.9 ± 34.7°;-0.04 ± 8.7°). Age, BMI and weight significantly correlated with flexions (p < 0.032). Motion patterns were identified through clustering.ConclusionsThis kinematic analysis has been proven to be a reliable diagnostic tool for the cervical range of motion. The non-unicity and variability of motion patterns through the clustering of motion strategy identification have been shown. Compensatory motions contributed to such motion pattern definition despite presenting significant intra-individual variability.

Variations in Respiratory Movements in Normal Subjects based on the Type of Chair Used

Variations in Respiratory Movements in Normal Subjects based on the Type of Chair Used

Propofol sedation reduces diaphragm activity in spontaneously breathing patients: ultrasound assessment.

The diaphragm is the most important respiratory muscle in humans, and the close relationship between inspired volume and diaphragmatic movement in normal subjects has led to investigations into diaphragmatic activity using ultrasound, during spontaneous breathing and sedative drug infusion. A total of 36 consecutive patients undergoing diagnostic procedures under deep propofol sedation were studied. Ultrasound measurements included the following: diaphragmatic thickening end-inspiration (TEI) and end-expiration (TEE). Diaphragmatic thickening fraction (DTF) was calculated from [(TEI - TEE) / TEE] at various time points (at T0 basal; at T1 during propofol infusion; at T2 awakening). Oxygen was administered at 4 L/min, and oxygen saturation (SpO2), end tidal CO2 (EtCO2) and respiratory rate (RR) were recorded. TEI, and TEE decreased by 26.7% and 17.4%, respectively, during propofol infusion (T0 versus T1) (P<0.001), and rapidly recovered at T2 (22.7% and 15.8%). At procedure end (T0 versus T2), TEI maintained a significant reduction (10%, P<0.001), whereas TEE recovered completely. DTF decreased by 56.7% at T1 (P<0.001) but increased by 76.9% (P=0.001) at T2. Recovery after awakening (T0 versus T2) did not reach the baseline value, with a 23.4% difference (P<0.001). SpO2 remained above 96% and EtCO2 below 43 mmHg with no desaturation episodes observed. Our study showed that deep propofol sedation affects muscle activity in healthy patients. While diaphragmatic strength decreased during sedation, there was no clinically relevant effect on SpO2. The study also confirmed that ultrasound is suitable for measuring diaphragm activity during a normal clinical procedure.

Assessing the clinical utility of combined movement examination in symptomatic degenerative lumbar spondylosis

ObjectivesThe aim of this study is to report the development and validation of a low back computer-aided combined movement examination protocol in normal individuals and record treatment outcomes of cases with symptomatic degenerative lumbar spondylosis. DesignTest–retest, following intervention. BackgroundSelf-report assessments and combined movement examination were used to record composite spinal motion, before and following neurosurgical and pain medicine interventions. Methods151 normal individuals aged from 20years to 69years were assessed using combined movement examination between L1 and S1 spinal levels to establish a reference range. Cases with degenerative low back pain and sciatica were assessed before and after therapeutic interventions with combined movement examination and a battery of self-report pain and disability questionnaires. Change scores for combined movement examination and all outcome measures were derived. FindingsComputer-aided combined movement examination validation and intraclass correlation coefficient with 95% confidence interval and least significant change scores indicated acceptable reliability of combined movement examination when recording lumbar movement in normal subjects. In both clinical cases lumbar spine movement restrictions corresponded with self-report scores for pain and disability. Post-intervention outcomes all showed significant improvement, particularly in the most restricted combined movement examination direction. InterpretationThis study provides normative reference data for combined movement examination that may inform future clinical studies of the technique as a convenient objective surrogate for important clinical outcomes in lumbar degenerative spondylosis. It can be used with good reliability, may be well tolerated by individuals in pain and appears to change in concert with validated measures of lumbar spinal pain, functional limitation and quality of life.

A novel ultrasound technique to measure genioglossus movement in vivo.

Upper airway muscles are important in maintaining airway patency. Visualization of their dynamic motion should allow measurement, comparison, and further understanding of their roles in healthy subjects and those with upper airway disorders. Currently, there are few clinically feasible real-time imaging methods. Methods such as tagged magnetic resonance imaging have documented movement of genioglossus (GG), the largest upper airway dilator. Inspiratory movement was largest in the posterior region of GG. This study aimed to develop a novel ultrasound (US) method to measure GG movement in real time. We tested 20 healthy, awake subjects (21-38 yr) breathing quietly in the supine posture with the head in a neutral position. US images were collected using a transducer positioned submentally. Image correlation analysis measured regional displacement of GG within a grid of points in the midsagittal plane throughout the respiratory cycle. Typically, motion began before inspiratory flow in an anteroinferior direction and peaked in midinspiration. Average peak displacements of the anterior, posterior, superior, and inferior grid points were 0.44 ± 0.23 (mean ± SD), 0.57 ± 0.35, 0.38 ± 0.20, and 0.62 ± 0.41 mm, respectively. Largest displacements occurred in the most inferoposterior part (0.70 ± 0.48 mm). This method had good intrarater repeatability within the same testing session, as well as across sessions. We have devised a simple noninvasive US method, which should be a useful tool to assess GG movement in normal subjects and those with sleep-disordered breathing.

Cortical activation change induced by neuromuscular electrical stimulation during hand movements: a functional NIRS study

ObjectivesNeuromuscular electrical stimulation (NMES) has been used in the field of rehabilitation for a long time. Previous studies on NMES have focused on the peripheral effect, in contrast, relatively little is known about the effect on the cerebral cortex. In the current study, we attempted to investigate the change of cortical activation pattern induced by NMES during execution of hand movements in normal subjects, using functional near infrared spectroscopy (fNIRS).MethodsTwelve healthy normal subjects were randomly assigned to the NMES group (six subjects) and the sham group (six subjects). We measured oxy-hemoglobin (HbO) in six regions of interest (ROI) during pre-NMES and post-NMES motor phase; the left dorsolateral and ventrolateral prefrontal cortex, premotor cortex, primary sensory-motor cortex (SM1), hand somatotopic area of SM1, and posterior parietal cortex. Between the pre-NMES and the post-NMES motor phases, real or sham NMES was applied on finger and wrist extensors of all subjects during a period of 5 minutes.ResultsIn all groups, during the pre-NMES motor phase, the HbO value in the hand somatotopic area of the left SM1 was higher than those of other ROIs. In the NMES group, during the post-NMES motor phase, HbO value variation in the hand somatotopic area of the left SM1 showed a significant decrease, compared with that of sham group (p < 0.05). However, in the sham group, similar aspect of results in HbO values of all ROIs was observed between pre-NMES and post-NMES motor phases (p > 0.05).ConclusionsResults of this study showed that NMES induced a decrease of cortical activation during execution of hand movements. This finding appears to indicate that application of NMES can increase the efficiency of the cerebral cortex during execution of motor tasks.

정상인의 기립 동작중의 대퇴 및 족부 반력의 비대칭율

The purpose of this study was to analyze the asymmetry of the reaction forces on lower limbs between dominant and nondominant sides during sit-to-stand movement in normal subjects. Fourteen normal subjects (<TEX>$22.6{\pm}2.3yrs$</TEX>, all men) participated in this study. To measure the reaction forces during sit-to-stand movement, two force plates were mounted on the ground and one dual top force plate was mounted on a chair. Five events(movement onset, max thigh reaction force, transition, max hip angle, seat off) were determined from the reaction force and joint angle trajectories. For each of thigh, foot, and total reaction forces, two-way ANOVA was performed with the events and sides as factors. Also investigated was the leg asymmetry expressed as the ratio of the reaction forces of dominant and nondominant sides. The significance of asymmetry was investigated and two-way ANOVA was performed with the events and body parts(foot, thigh and total) as factors. Thigh reaction force and total reaction force showed interaction of events and leg sides(p < 0.01). Post-hoc comparisons showed they were different between sides at the latter stage(transition, max hip angle, and seat off events) (p < 0.01). Asymmetry was also significant at the latter stage(transition, max hip angle, and seat off events) (p < 0.01). Interaction of events and body parts on asymmetry was significant(p < 0.01) and asymmetry was greater in thigh reaction forces than total and foot reaction forces at the events of the latter stage(p < 0.01). The results suggest that asymmetry exist in normal subject and should be fully considered when investigating sit-to-stand strategy of patients.

A Goniometric study of radial and ulnar deviation in the population of central Gujarat

Introduction: In the study of range of movement of wrist joint, accurate measurements on normal subjects are important since these have a bearing on diagnosis and prognosis in disease state. Objective: To determine the effects of age and gender on wrist motion in normal subjects on both hands. Material and Method: Four hundred subjects (Two hundred male and Two hundred Female) with the four age groups with no history of injury to the wrist joint were subjected to goniometric measurements with the wrist in ulnar and radial deviation of both hands through universal goniometer in Central Gujarat population. Result: Readings were noted, the radial deviation and total range of motion were higher in left hand as compared to right (p=<0.005). In addition, Female subjects showed higher range of motion than male and joint range of movement decrease with the increase of the age(r= -0.147 in right hand and r= -0.243 in left hand). Conclusion: The range of motion was reduced with the increases of age because of the presence of osteoporosis, cumulative damage and obesity with ageing process. Generally, females tend to have greater range of motions, due to the anatomical and physiological differences, such as the size of muscle mass, joint geometry and hormone. The reduced mobility on the right side compare with that on the left might have been the result of slight degenerative changes in the joint as well as damage to the ligaments of the right upper extremity in the right handed population.

Vestibular-somatosensory convergence in head movement control during locomotion after long-duration space flight1

Space flight causes astronauts to be exposed to adaptation in both the vestibular and body load-sensing somatosensory systems. The goal of these studies was to examine the contributions of vestibular and body load-sensing somatosensory influences on vestibular mediated head movement control during locomotion after long-duration space flight. Subjects walked on a motor driven treadmill while performing a gaze stabilization task. Data were collected from three independent subject groups that included bilateral labyrinthine deficient (LD) patients, normal subjects before and after 30 minutes of 40% bodyweight unloaded treadmill walking, and astronauts before and after long-duration space flight. Motion data from the head and trunk segments were used to calculate the amplitude of angular head pitch and trunk vertical translation movement while subjects performed a gaze stabilization task, to estimate the contributions of vestibular reflexive mechanisms in head pitch movements. Exposure to unloaded locomotion caused a significant increase in head pitch movements in normal subjects, whereas the head pitch movements of LD patients were significantly decreased. This is the first evidence of adaptation of vestibular mediated head movement responses to unloaded treadmill walking. Astronaut subjects showed a heterogeneous response of both increases and decreases in the amplitude of head pitch movement. We infer that body load-sensing somatosensory input centrally modulates vestibular input and can adaptively modify vestibularly mediated head-movement control during locomotion. Thus, space flight may cause central adaptation of the converging vestibular and body load-sensing somatosensory systems leading to alterations in head movement control.

Event-related desynchronization of motor cortical oscillations in patients with multiple system atrophy

Multiple system atrophy (MSA) is a progressive neurodegenerative disease characterized by parkinsonism (MSA-P), cerebellar and autonomic deficits. In Parkinson's disease (PD), an impaired modulation of motor cortical mu and beta range oscillations may be related to the pathophysiology of bradykinesia. Event-related desynchronization (ERD) of these oscillations occur for 1-2s preceding a voluntary movement in normal subjects and patients with PD treated with levodopa while only lasting around 0.5s in untreated patients. Motor cortical rhythms were recorded from subdural strip electrodes in three patients with MSA-P while taking their regular dopaminergic medications. Following a ready cue, patients performed an externally cued wrist extension movement to a go cue. In addition, recordings were obtained during imagined wrist extension movements to the same cues and during self-paced wrist extensions. ERD and event-related synchronization were examined in subject-specific frequency bands. All patients showed movement-related ERD in subject-specific frequency bands below ~40Hz in both externally cued and self-paced conditions. Preparatory ERD latency preceding self-cued movement was 900ms in one patient and at or after movement onset in the other two patients. In the externally cued task, a short lasting (<1.3s) ready cue-related ERD that was not sustained to movement onset was observed in two patients. Imagined movements resulted in go cue-related ERD with a smaller magnitude in the same two patients. These results indicate that the modulation of motor cortical oscillations in patients with MSA that are treated with levodopa is similar to that occurring in untreated patients with PD. The findings suggest that cortical activation in patients with MSA is diminished, may be related to pathophysiological changes occurring in the basal ganglia and correlates with the poor clinical response that these patients typically obtain with dopaminergic therapy.

Estimation method of finger tapping dynamics using simple magnetic detection system

We have developed the simple estimation method of a finger tapping dynamics model for investigating muscle resistance and stiffness during tapping movement in normal subjects. We measured finger tapping movements of 207 normal subjects using a magnetic finger tapping detection system. Each subject tapped two fingers in time with a metronome at 1, 2, 3, 4, and 5 Hz. The velocity and acceleration values for both the closing and opening tapping data were used to estimate a finger tapping dynamics model. Using the frequency response of the ratio of acceleration to velocity of the mechanical impedance parameters, we estimated the resistance (friction coefficient) and compliance (stiffness). We found two dynamics models for the maximum open position and tap position. In the maximum open position, the extensor muscle resistance was twice as high as the flexor muscle resistance and males had a higher spring constant. In the tap position, the flexor muscle resistance was much higher than the extensor muscle resistance. This indicates that the tapping dynamics in the maximum open position are controlled by the balance of extensor and flexor muscle friction resistances and the flexor stiffness, and the flexor friction resistance is the main component in the tap position. It can be concluded that our estimation method makes it possible to understand the tapping dynamics.

Reproducibility and validity of digital inclinometry for measuring cervical range of motion in normal subjects

Measurements of cervical range of motion (CROM) have been extensively reported in the past decade employing simple (goniometers) as well as sophisticated (electro-, magneto- and ultrasonography-based) systems. The recent introduction of the simple, user-friendly and relatively cheap digital inclinometer (DI) has opened a potentially new venue for measurement of this segment's motion. The purpose of the present study was to assess intra-tester reproducibility of DI-based findings as well as its validity in comparison to the ultrasonography-based Zebris CMS 70P (Zebris Medizintechnik Gmbh, Isny, Germany) for measuring CROM in normal subjects. Active CROM of healthy women (n = 15) and men (n = 15) aged 24.2(2.4) years was measured on two sessions, Test 1 and Test 2, spread over 7.2(+/-0.7) days apart. On Test 1, the six primary movements of the neck (flexion, F; extension, E; right and left lateral flexion, RLF and LLF; and right and left rotations, RR and LR) were measured using the DI and the Zebris. On Test 2, the same measurements were performed using the DI only. All measurements were conducted by the same tester, with the subject in the seated position. The only exception was DI measurement of cervical rotation that was performed in the supine position due to the DI gravity-dependence, rendering DI measurements in the transverse plane irrelevant. No significant differences were revealed between the two instruments with respect to the sagittal and frontal planes, whereas the DI-based CROM in rotation was significantly greater then its Zebris-based counterpart. The inter-device interclass correlation coefficients (ICCs) for the frontal were 0.72 (RLF) and 0.62 (LLF), and 0.77 (F) and 0.83 (E). Poor correlations were indicated for the rotations. The intra-tester reproducibility derived from the test-retest DI measurement indicated good to excellent reproducibility in all planes with ICCs ranging from 0.82 (LLF) to 0.94 (E). The Standard Error of Measurement ranged from 1.6 degrees (RR) to 2.6 degrees (F). DI-based CROM measurements are reproducible and valid for recording sagittal and frontal plane motions in healthy subjects. The higher range in rotations, relative to the Zebris-based findings, is most probably attributable to the test position. Being relatively cheap, portable and convenient for tester and subject alike, the DI seems to be an effective instrument for assessing CROM.

Vestibular and proprioceptive influences on trunk movements during quiet standing

We characterized upper trunk and pelvis motion in normal subjects and in subjects with vestibular or proprioceptive loss, to document upper body movement modes in the pitch and roll planes during quiet stance. Six bilateral vestibular loss (VL), six bilateral lower-leg proprioceptive loss (PL) and 28 healthy subjects performed four stance tasks: standing on firm or foam surface with eyes open or closed. Motion of the upper body was measured using two pairs of body-worn gyroscopes, one mounted at the pelvis and the other pair at the shoulders. Pitch and roll angular velocities recorded from the gyroscopes were analyzed separately for low-frequency (<0.7 Hz) and high-frequency (>3 Hz) motion. Low-frequency pitch motion was similar for all groups, consisting of in-phase pelvis and shoulder motion. High-frequency pitch motion in controls and VL subjects was dominated by pelvis motion with little shoulder motion, but vice versa in PL subjects. Low-frequency roll motion changed for all groups from mainly shoulder and little pelvis motion to in-phase pelvis and shoulder motion after moving from a firm to foam surface. In contrast, high-frequency roll motion changed from mainly shoulder motion to mainly pelvis motion with the change to a foam surface, except for PL subjects with eyes closed. Coherent low-frequency sway between pelvis and shoulder was only pronounced in VL patients. These results indicate that relative motion between the pelvis and shoulder depends on the support surface, the type of sensory loss, and whether the motion is in roll or pitch plane. Furthermore, relative motion between the pelvis and upper trunk is an integral part of movement modes used to control quiet stance. Vestibular loss patients showed very similar movement modes as controls, with larger amplitudes. Proprioceptive loss patients, however, used more shoulder motion and stabilized the pelvis for the high-frequency mode. We conclude that there is relative motion between the upper trunk and pelvis during quiet stance and suggest that it may contribute to balance control.

The hodology of hallucinations

The hodotopic framework is a recent revision of Geschwind's disconnection paradigm incorporating advances in functional and white matter imaging. Its intention is to help clinico-pathological correlations across a range of neurological and psychiatric conditions and generate novel research questions. Here I consider hallucinations within this framework. The paper is divided into three parts. The first reviews the auditory and visual hallucination literature from the dual perspectives of dysfunction localised to specific brain regions (topological) and dysfunction related to connections between brain regions (hodological), combining evidence from tractography, functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) studies. Patients prone to hallucinations have complex, task-specific hodological abnormalities that persist between hallucination episodes. During hallucinations, topological increases in activity are found whose location defines hallucination content and modality. Whether these activity increases are accompanied by transient hodological change is unclear. The second part of the paper addresses this issue in EEG and fMRI studies of a 200-year-old paradigm. Photic stimulation within a specific frequency and luminance range induces hallucinations of geometrical patterns, colours and motion in normal subjects. By comparing hallucination-inducing with control stimulation, topological activity increases were identified in visual areas whose specialisations matched the induced hallucination contents. During hallucinations, fMRI connectivity between LGN and cortex changed from a positive to negative relationship while EEG connectivity between occipital and other brain regions increased. The complex and dynamic topological and hodological changes during induced hallucinations are consistent with a shift in thalamocortical circuitry from tonic to burst mode and may have direct relevance to the Charles Bonnet Syndrome. The third part of the paper considers the relevance of the finding to other disorders, examines the strengths and limitations of our current imaging approaches to connectivity and looks to future developments in the field.

F-MRI in Epilepsy with Spike and Wave Activity Evoked by Eye Closure: Different Bold Activation in a Patient with Idiopathic Partial Epilepsy with Occipital Spikes and a Control Group

We performed functional magnetic resonance imaging (fMRI) in a 30-year-old man with idiopathic partial epilepsy with occipital spikes whose scalp EEG activity was characterized by persistent epileptiform discharges on eye closure, ceasing upon eye opening. We compared BOLD activation in the patient and in a control group of three normal volunteers. f-MRI showed that occipital cortex and frontal areas were activated in relation to eye movement in normal subjects during eye opening but not during eye closing. While persistent interictal spike and wave activity was present over the posterior and anterior scalp in the patient upon eye closing, f-MRI showed bilateral activation of the parietal and temporal regions. This fMRI study documents the activation of posterior and temporal areas related to continuous intercritical spikes evoked by eye closure, which are diffuse over the scalp. This activation was absent in the control group during eye closure.

The Effects of Heel Elevation on Postural Adjustment and Activity of Lower-Extremity Muscles during Deep Squatting-to-Standing Movement in Normal Subjects

The effects of various heel elevations on postural adjustment and lower-extremity muscle activity during the squat-to-stand (SQ-ST) movement were investigated. Eight healthy male subjects participated in the experiment, which involved rising from a deep squat with three different heel elevations: a full squat (FS), in which the plantar aspects of the feet were in full contact with the floor (0 degree), slope squat (SS), in which a 15-degree wedge was applied underneath the foot, and tiptoe squat (TS), in which subjects lifted their heels to their preferred height by extending the metatarsophalangeal joint. Electromyograms were taken of the extensor digitorum brevis (EDB), tibialis anterior (TA), rectus femoris (RF), and gastrocnemius (G) muscles. The results showed that heel elevation significantly affected the postural adjustment: TS caused significantly smaller anterior displacement in the knee and the hip during ankle dorsiflexion and minimized the duration of the forward movement required to stand. On the other hand, EDB activity strongly increased in TS. However, use of foot slope appeared to decrease activities of RF, TA, and EDB. These findings suggest that the use of a foot slope to achieve a squat-to-stand movement may be appropriate to assist patients with weak lower-extremity muscles.

Effects of 5 Hz subthreshold magnetic stimulation of primary motor cortex on fast finger movements in normal subjects

We evaluated the effects of high-frequency repetitive transcranial magnetic stimulation (rTMS) on motor performance and motor learning of a rapid index finger movement. Two groups of healthy right-handed subjects underwent either "real" rTMS (1800 stimuli over the first dorsal interosseous (FDI) muscle hot spot given at 5 Hz and intensity of 90% of resting motor threshold-RMT) or "sham" stimulation. Both groups performed 60 rapid abductions of the right index finger before and after rTMS. The kinematic variables measured were amplitude, duration, peak velocity and peak acceleration. We also evaluated RMT and motor-evoked potential (MEP) amplitude before, 5 and 30 min after rTMS. In both groups practice significantly increased peak velocity, peak acceleration and amplitude and decreased movement duration independently from the type of intervention ("real" and "sham"). "Real" rTMS significantly increased cortical excitability as measured by MEP amplitude whereas "sham" rTMS did not. In our study, 5 Hz rTMS failed to improve either the motor performance or the motor learning of a rapid index-finger abduction despite the increase in cortical excitability of the primary motor cortex. Since motor behaviour engages a distributed cortical and subcortical neuronal network, excitatory conditioning of the primary motor cortex is probably not sufficient to influence the behavioural output.

Estimation of Cortical Connectivity in Humans: Advanced Signal Processing Techniques

In the last ten years many different brain imaging devices have conveyed a lot of information about the brain functioning in different experimental conditions. In every case, the biomedical engineers, together with mathematicians, physicists and physicians are called to elaborate the signals related to the brain activity in order to extract meaningful and robust information to correlate with the external behavior of the subjects. In such attempt, different signal processing tools used in telecommunications and other field of engineering or even social sciences have been adapted and re-used in the neuroscience field. The present book would like to offer a short presentation of several methods for the estimation of the cortical connectivity of the human brain. The methods here presented are relatively simply to implement, robust and can return valuable information about the causality of the activation of the different cortical areas in humans using non invasive electroencephalographic r cordings. The knowledge of such signal processing tools will enrich the arsenal of the computational methods that a engineer or a mathematician could apply in the processing of brain signals. Table of Contents: Introduction / Estimation of the Effective Connectivity from Stationary Data by Structural Equation Modeling / Estimation of the Functional Connectivity from Stationary Data by Multivariate Autoregressive Methods / Estimation of Cortical Activity by the use of Realistic Head Modeling / Application: Estimation of Connectivity from Movement-Related Potentials / Application to High-Resolution EEG Recordings in a Cognitive Task (Stroop Test) / Application to Data Related to the Intention of Limb Movements in Normal Subjects and in a Spinal Cord Injured Patient / The Instantaneous Estimation of the Time-Varying Cortical Connectivity by Adaptive Multivariate Estimators / Time-Varying Connectivity from Event-Related Potentials