Finger Extension Movements Research Articles

Motor cortical reorganization is present after a single attack of multiple sclerosis devoid of cortico-spinal dysfunction

While occurrence of motor cortical reorganization has been clearly demonstrated in patients with multiple sclerosis (MS), it is not yet clear whether this cortical reorganization constitutes a response to cortico-spinal lesions or to more diffuse damage affecting the neuronal network involved in motor act preparation, or both. We proposed to investigate the changes in the activation pattern during a simple motor task devoid of cortico-spinal dysfunction occurring in patients with clinically isolated syndrome (CIS) suggestive of MS. Among 15 right-handed CIS patients, we selected eight patients with a preserved central motor pathway established by motor evoked potentials. Ten healthy right-handed gender- and age-matched volunteers were also included. After morphological MRI, subjects performed calibrated conjugated finger flexion and extension movements during fMRI acquisition. In CIS patients, simple movements of the non-dominant hand induced recruitment of the anterior cingulate cortex (BA32) usually involved in complex motor movements. This reorganization was correlated with the diffuse brain tissue damage (brain T₂ lesion load). These results suggest that at least part of the cortical reorganization observed during very simple tasks in the earliest stage of MS occurs whether or not the efferent pathways are intact.

Force control and degree of motor impairments in chronic stroke

Objective This study determined the variability and regularity of force production in impaired upper extremities of chronic stroke survivors. Two hypotheses included: (1) stroke will increase the variability and regularity of force output in comparison to age-matched controls and (2) degree of motor impairments will be positively correlated with the variability and regularity of force output. Methods Nine chronic stroke and nine age-matched controls performed unimanual isometric wrist and finger extension movements for 20 s to three different target force levels. Force output was indexed by magnitude, accuracy, variability, and regularity. Stroke motor impairment levels were determined by Fugl-Meyer upper extremity assessment. Results The stroke group demonstrated increased variability and regularity of the force output. Further, motor impairments scaled with increase in variability and regularity of force output. Conclusions The variability and regularity of force differentiated isometric contractions performed by chronic stroke survivors from age-matched controls. Moreover, in clinical settings an objective assessment of force control on variability and regularity appears to be most meaningful at 25% of MVC. Significance Increased variability contributes to reduced steadiness in force output. Increased regularity characterizes the adaptability losses in motor capabilities following stroke. This knowledge may facilitate planning and evaluating rehabilitation protocols.

High-frequency transcutaneous electrical nerve stimulation (TENS) differentially modulates sensorimotor cortices: An MEG study

Transcutaneous electrical nerve stimulation (TENS) affects excitability of the central motor system as well as the somatosensory system. To determine whether TENS has influence on excitability in the sensorimotor cortices of TENS-treated finger muscle, we investigated magnetoencephalogram associated with voluntary, self-paced finger movement before and after TENS. High-frequency TENS was applied on the extensor digitorum muscle for 15 min. Subjects underwent alternate middle finger and thumb extension movements before and after the TENS. We recorded movement-related cortical magnetic field (MRCF) associated with TENS-treated middle finger movement and that from untreated thumb movement. The current source for motor field (MF) was located in the pre-central motor cortex and anteriorly-oriented, and that for motor evoked field one (MEF1) was found in the post-central somatosensory cortex and posteriorly-oriented. The amplitude of MF for TENS-treated middle finger movement decreased but unchanged for untreated thumb movement after TENS. The amplitude of MEF1 decreased for either finger movement after TENS. High-frequency TENS to the forearm muscle modulates excitability of the limited area of motor cortex but wider area of primary somatosensory cortex. High-frequency TENS to the forearm muscle modulates excitability of the primary somatosensory cortex and motor cortex in a different manner.

Mirror Therapy Improves Hand Function in Subacute Stroke: A Randomized Controlled Trial

Yavuzer G, Selles R, Sezer N, Sütbeyaz S, Bussmann JB, Köseoğlu F, Atay MB, Stam HJ. Mirror therapy improves hand function in subacute stroke: a randomized controlled trial. Objective To evaluate the effects of mirror therapy on upper-extremity motor recovery, spasticity, and hand-related functioning of inpatients with subacute stroke. Design Randomized, controlled, assessor-blinded, 4-week trial, with follow-up at 6 months. Setting Rehabilitation education and research hospital. Participants A total of 40 inpatients with stroke (mean age, 63.2y), all within 12 months poststroke. Interventions Thirty minutes of mirror therapy program a day consisting of wrist and finger flexion and extension movements or sham therapy in addition to conventional stroke rehabilitation program, 5 days a week, 2 to 5 hours a day, for 4 weeks. Main Outcome Measures The Brunnstrom stages of motor recovery, spasticity assessed by the Modified Ashworth Scale (MAS), and hand-related functioning (self-care items of the FIM instrument). Results The scores of the Brunnstrom stages for the hand and upper extremity and the FIM self-care score improved more in the mirror group than in the control group after 4 weeks of treatment (by 0.83, 0.89, and 4.10, respectively; all P<.01) and at the 6-month follow-up (by 0.16, 0.43, and 2.34, respectively; all P<.05). No significant differences were found between the groups for the MAS. Conclusions In our group of subacute stroke patients, hand functioning improved more after mirror therapy in addition to a conventional rehabilitation program compared with a control treatment immediately after 4 weeks of treatment and at the 6-month follow-up, whereas mirror therapy did not affect spasticity.

Active Finger Extension

Early prognosis of arm recovery is a major clinical issue in stroke. The aim of this study was to assess the prognostic value of 4 simple bedside tests. Forty-eight patients with arm paresis/plegia were evaluated on days 7, 14, 30, 90 and 180 after stroke. Assessment included 4 potential predictors of arm recovery (active finger extension, shoulder abduction, shoulder shrug and hand movement scales) and 3 outcome measures evaluating arm function (Nine Hole Peg Test, Fugl-Meyer arm subtest, Motricity Index arm subtest). The active finger extension scale was the most powerful prognostic factor. Patients with active finger extension scores >3 had a high probability of achieving good performance as assessed by the Motricity Index. Active finger extension is a reliable early predictor of recovery of arm function in stroke patients.

Cortical regulation during the early stage of initiation of voluntary swallowing in humans.

The aim of the present study was to reveal the spatiotemporal relations among cortical regions involved in the initiation of voluntary swallowing in humans using magnetoencephalography (MEG). As a control task, finger extension movement, which is purely voluntary, was also investigated using the same techniques. The swallowing-related activity was distributed widely for 2000 ms before the electromyogram onset of the right suprahyoid muscle; however, the finger-related activity occurred in the late stage of the recording. The cingulate cortex, the insula, and the inferior frontal gyrus were the main loci active prior to swallowing. These cortical loci coincide with those suggested by previous human brain mapping studies that investigated the brain mechanism which controls swallowing. Activation in the cingulate cortex was registered in the early stage of swallowing and could be related to the cognitive process regarding the food being safe to swallow. The activation in the insula lasted for a long time before the initiation of swallowing. This suggests that the long-lasting activation in the insula prior to swallowing is essential for the initiation of swallowing.

Pulsatile control of the human masticatory muscles.

Spectral analysis of jaw acceleration confirmed that the human mandible 'trembles' at a peak frequency around 6 Hz when held in its rest position and at other stationary jaw openings. The 6 Hz tremor increased during very slow movements of the mandible, but other lower-frequency peaks became prominent during more rapid jaw movements. These lower-frequency peaks are likely to be the result of asymmetries in the underlying, voluntarily produced, 'saw-tooth' movements. In comparison, finger tremor at rest and during slow voluntary movements had a mean peak frequency of about 8 Hz: this frequency did not change during rhythmical finger flexion and extension movements, but the power of the tremor increased non-linearly with the speed of the movement. The resting jaw tremor was weakly coherent with the activity of the masseter and digastric muscles at the tremor frequency in about half the subjects, but was more strongly coherent during voluntary movements in all subjects. The masseter activity was at least 150 deg out of phase with the digastric activity at the tremor frequency (and at all frequencies from 2.5-15 Hz). The alternating pattern of activity in antagonistic muscles at rest and during slow voluntary movements supports the idea that the masticatory system is subject to pulsatile control in a manner analogous to that seen in the finger.

Dual representation of the hand in the cerebellum: activation with voluntary and passive finger movement

Early electrophysiological studies during sensory stimulation in the anesthetized cat and more recent functional imaging studies during voluntary movement in humans have provided evidence for two separate representations of the body in the anterior and posterior lobes of the cerebellum; however, the functional role of these body maps in motor and sensory processing is not known. The aims of the present study were to determine whether this dual representation is also present during passive movement, and to compare the pattern of activation with that obtained during voluntary movement. Functional MRI measurements were undertaken in 14 subjects who performed right index finger flexion and extension movements at ∼1 Hz, or had their finger moved passively at the same rate and through the same angle using a pneumatic device. During passive movement, dual activation was detected in the ipsilateral cerebellum, in the anterior lobe, and in the posterior lobe. A similar pattern of activation was observed during voluntary movement; however, the overall magnitude was about doubled. These data provide evidence for a dual ipsilateral representation of the hand in the rostral and caudal cerebellar cortex during passive as well as voluntary movements, with the rostral representation being the dominant one, and indicate that both of these areas are involved in kinesthetic sensory and motor processing.

EFFECTS OF SERIAL VISUOMOTOR TASKS ON CONTINGENT NEGATIVE VARIATION

We evaluated contingent negative variation (CNV) in 15 right-handed normal subjects who performed simple finger extension (NB) or skilled finger movement task with visual guidance (B). When subjects performed serial tasks of NB-B1 (first block of B)-B2 (second block of B), the CNV amplitudes were larger in BI compared with NB at the left frontoparietal leads for early CNV, at widely distributed areas for the middle CNV and at the left fronto-patietal and right frontal leads for late CNV. The present results suggest that the frontoparietal area involving the prefrontal and sensorimotor cortices, plays an important role in visuomotor learning.

The electroencephalographic β synchronization following extension and flexion finger movements in humans

The cortical post-movement β synchronization (PMBS) following brisk extension-flexion and flexion-extension movements of the right index finger was analyzed in twelve right-handed subjects using electroencephalographic recordings. The amplitude of PMBS over the contralateral sensorimotor area was enhanced and the focus of PMBS was widespread when finger flexion was the last movement. The results suggest that finger extension and flexion movements induce unequal β synchronization over the contralateral M1 area possibly due to different complexity of the neuronal networks controlling these movements.

Brain activation during human finger extension and flexion movements

Corticospinal projections to the motor neuron pool of upper-limb extensor muscles have been reported to differ from those of the flexor muscles in humans and other primates. The influence of this difference on the central nervous system control for extension and flexion movements is unknown. Cortical activation during thumb extension and flexion movements of eight human volunteers was measured using functional magnetic resonance imaging (fMRI), which detects signal changes caused by an alteration in the local blood oxygenation level. Although the relative activity of the extensor and flexor muscles of the thumb was similar, the brain volume activated during extension was substantially larger than that during flexion. These fMRI results were confirmed by measurements of EEG-derived movement-related cortical potential. Higher brain activity during thumb extension movement may be a result of differential corticospinal, and possibly other pathway projections to the motoneuron pools of extensor and flexor muscles of upper the extremities.

Coactivation of the flexor muscles as a synergist with the extensors during ballistic finger extension movement in trained kendo and karate athletes.

To analyse the effects of ballistic property training on ballistic finger extension movement, surface electromyographic pattern (EMGs) of the finger extensor and flexor muscles and the acceleration signal of the middle finger were recorded in trained kendo and karate athletes, and sedentary non-athletic men. Ballistic finger extension did not show the characteristic triphasic EMG pattern reported in single joint, but a coactivation of flexor and extensor muscles. Reaction time (RT) in kendo (143 +/- 12 msec) and karate (146 +/- 11 msec) athletes were significantly shorter than that in the control (176 +/- 12 msec). The shortenings of the RT were attributed to both the shortenings of premotor time and motor time. The delay of the flexor muscles discharge after those of the extensors in kendo (0.8 +/- 7.0 msec) and karate (-0.2 +/- 5.0 msec) athletes was significantly shorter than in control (12.7 +/-5.6 msec). These results suggest that the RT is shortened through motor learning in the kendo and karate athletes who trained for momentary movements; and that the flexor muscles may play an important role as a synergist in heightening the efficiency of ballistic finger extension in coordination with the extensor muscles.

Inter-hemispheric lateralization of event related potentials; motoric versus non-motoric cortical activity

To study hemispheric lateralization of cortical potentials associated with motoric and non-motoric function, cortical activity was recorded accompanying either finger extension or saccadic eye movements in a contingent negative variation (CNV) paradigm. Subjects viewed computer-generated pacing stimuli, presented in the left visual hemi-field, and were instructed to either initiate or inhibit a motor response following an imperative signal. Motoric lateralization was assessed by means of the lateralized readiness potential (LRP). In addition, a measure complementary to the LRP was introduced to investigate non-motoric lateralization (NML). Contralateral inter-hemispheric lateralization was evident in the LRP preceding finger movement, but was absent prior to eye movements. However, pre-saccadic cortical response profiles did exhibit a right hemispheric, non-motoric lateralization (NML) during stimulus presentation. Comparable non-motoric lateralization was found for finger extension. Results of the present study suggest that non-motoric lateralization may be a contributing factor to the frequently reported inter-hemispheric asymmetry preceding self-initiated saccadic eye movements. Results of the present study also suggest that the latter may be related to a covert shift of visuospatial attention toward the saccadic target. Associated shifts of attention are suppressed in a CNV paradigm, where attentional focus is primarily on the CNV stimulus during the pre-saccade period.

Analysis of voluntary finger movements during hand tasks by a motion analyzer

Finger movements have primarily been classified by the final position of the hand and finger during deliberate hand activities, rather than as a description of the movement process. In addition, as of yet there have been no reports based upon objective data from the analysis of the motion of three finger joints during movement, and no reports exist that describe the relationship of the three joints' motion during these movements. This paper describes the relationship of the three finger joints during simple finger movements and hand tasks using measurements and analysis from a two-dimensional motion analyzer. Two prehensile movements were examined in 15 healthy volunteers: pure finger extension from finger flex position in different wrist positions (dorsi-flexion position, neutral position and palmar-flexion position of the wrist joint) and the grasping of discs of different diameter (10, 11, 12 and 13 cm). In the sequence of pure finger extension, where the grasping task was not requested, results showed that the movement was started from the proximal joint and extended to the distal joint of the finger, and full finger extension accomplished from distal to proximal, one after another, in any wrist position in most subjects. With the grasping of a disc, however, joint movement was initiated from distal to proximal and the final motion for grasping was carried to completion from the proximal to distal joints of the finger in most subjects. In addition, it was recognized that the proportion of the angular change in each of the three joints was different, as were the time duration of the joint motion and the pattern of the angular change. From these results, it is suggested that deliberate activities of the finger and sophisticated joint movements provided delicate adjustments to fit the fingers to the size of the object, as compared to the simple finger extension movement.

After‐effects on stiffness and stretch reflexes of human finger flexor muscles attributed to muscle thixotropy.

1. While the subject maintained a weak contraction in his finger flexor muscles, holding the metacarpophalangeal joints in 45 deg flexion, test torque pulses were applied which caused rapid finger extension movements and electromyographic (EMG) stretch reflex responses. Before each test pulse the fingers were passively flexed or extended ('post-short' and 'post-long' trials) for about 10 s. The EMG and joint deflection responses in the two types of trial were compared after averaging. 2. In the 'post-long' trials, the EMG reflex response showed a comparative increase in latency, with a reduction of the short-latency (M1) component and an enhancement of the medium-latency (M2) component. 3. The angular deflections were larger, and the turning points of the deflections, which indicated the start of the mechanical reflex responses, occurred later in the 'post-long' trials. These differences were not seen when the torque pulse was immediately preceded by a strong, brief isometric finger flexor contraction in the test position. 4. Immediately following the return to the test position the background finger flexor EMG activity was larger in the 'post-long' trials, a difference which gradually subsided over 15-20 s. A strong, brief contraction in the test position also eliminated this inter-trial difference. 5. The results are interpreted as manifestations of thixotropic after-effects in intra- and extrafusal muscle fibres. It is proposed that the M1 component of the stretch reflex is largely a response to the 'initial burst' of impulses in primary spindle afferents.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of specific priming degree on suppression duration

Subjects participated in a choice reaction time (RT) task using visual stimuli with finger flexion and extension movements serving as potential responses. On some occasions subjects had to produce paired movements, while on other trials, one response had to be initiated, the other suppressed. Two general Priming Types (Non-Specific, Specific) and Priming Degrees (low, high) were manipulated. The main objective was to determine whether suppression duration and Specific priming degree (i.e., preparation intensity) were directly related. If so, it would explain why RTs associated with incorrect predictions have progressively lengthened as Prediction Probability size (held to alter Specific priming degree) has been increased, given the assumption that the urge to initiate an inappropriately prepared output must be suppressed before the production of the needed response can occur. This explanation was not supported as suppression duration remained invariant as Specific priming levels were altered; however, it did lengthen as Non-Specific priming degree increased.

Discharge in muscle spindle afferents related to direction of slow precision movements in man.

Single-unit activity was recorded with needle electrodes in eighteen muscle spindle afferents (eleven primaries, seven secondaries) from finger extensor muscles in the radial nerve of awake human subjects. The discharge rate of the afferents was determined during precisely controlled voluntary movements. The subjects performed a standardized visual ramp-and-hold tracking task, which included very slow finger extension and flexion movements (2.5 deg/s) with an amplitude of 20 deg. Throughout the tracking task a constant torque load of small or intermediate size, i.e. less than 30% of maximum voluntary contraction force, opposed finger extension. Altogether, 131 trials were studied. For most units the discharge rate was lower during shortening compared with active position holding, and it was higher during lengthening contractions. Thus, the majority of units responded to phasic stretch during the active movements, although the size of the movement response varied considerably between units and was never large. A few units even exhibited a reversed stretch response pattern. Hence, when estimated from pooled data, movement responses of the unit sample as a whole were small, around 1 impulse/s. The over-all response pattern of an individual afferent during the tracking task was very similar between successive tests. Although the discharge rate of most units increased with the load during movements as well as during position holding, the presence as well as the magnitude of movement responses depended only little on the size of the load. However, a few afferents exhibited a stretch response pattern with small loads and a reversed stretch response pattern with larger loads. In spite of the predominant increase of afferent firing during muscle lengthening there was no systematic modulation of the discharge rate in relation to the joint angle during the active movements, either in the primary or in the secondary afferents. The present findings suggest that human muscle spindles provide information about the occurrence as well as the direction of slow isotonic movements at low velocities in a precision motor task. This is in contrast to the lack of accurate position response which has previously been demonstrated.

Visually Elicited Finger Movements in Infants

The relationship between visual stimulus intensity and finger movements was examined in infants from 10 to 15 weeks of age and from 20 to 25 weeks of age who were shown a cone that varied in size, brightness, and distance from them. 2 hypotheses derived from Schneirla's approach-withdrawal theory were examined; (1) that responses of the younger infants would be directly related to stimulus intensity, with finger extension (approach) movements elicited by weak stimuli and flexion (withdrawal) movements elicited by more intense stimuli; and (2) that stimulus dimensions such as distance, size, and brightness would make additive contributions to stimulus intensity, so that combinations of weak intensity would elicit finger extension and combinations of strong intensity would elicit flexion. Analyses of variance indicated no significant main effects of distance, size, or brightness, but significant age, intensity, and age x intensity effects. Older infants tended to extend their fingers more than younger infants. However, as intensity increased, the younger infants' responses showed decreases in extension and increases in flexion, while the older infants' responses indicated no clear relationship between intensity and response direction. That younger infants were responsive to the quantitative rather than the qualitative aspects of stimulation has important implications for understanding how various stimulus dimensions affect infant responses.