Search results for "Motor"
showing 10 items of 3137 documents
Changes in the probability of firing of motor units following electrical stimulation in human limb muscles
1986
Changes in the probability of motor unit firing was studied in ten different muscles (six muscles in the upper extremity and four muscles in the lower extremity) of eleven healthy human subjects. The responses were elicited by the electrical stimulation of cutaneous or mixed nerves during weak voluntary contraction of the muscle studied, and were recorded by averaging the rectified surface electromyogram. In eight of the ten muscles, well-detectable, short and long latency excitatory phases were observed. The most constant and well-identified excitatory responses were observed in the first interosseus dorsalis muscle in the hand, and in the extensor digitorum brevis muscle in the foot. Thes…
Effects of muscle action type on corticospinal excitability and triceps surae muscle-tendon mechanics.
2018
This study investigated whether the specific motor control strategy reported for eccentric muscle actions is dependent on muscle mechanical behavior. Motor evoked potentials, Hoffman reflex (H-reflex), fascicle length, pennation angle, and fascicle velocity of soleus muscle were compared between isometric and two eccentric conditions. Ten volunteers performed maximal plantarflexion trials in isometric, slow eccentric (25°/s), and fast eccentric (100°/s) conditions, each in a different randomized testing session. H-reflex normalized by the preceding M wave (H/M) was depressed in both eccentric conditions compared with isometric ( P < 0.001), while no differences in fascicle length and pe…
Cutaneous Painful Laser Stimuli Evoke Responses Recorded Directly From Primary Somatosensory Cortex in Awake Humans
2004
Negative and positive laser evoked potential (LEP) peaks (N2*, P2**) were simultaneously recorded from the primary somatosensory (SI), parasylvian, and medial frontal (MF: anterior cingulate and supplementary motor area) cortical surfaces through subdural electrodes implanted for the surgical treatment of intractable epilepsy. Distribution of the LEP N2*and P2**peaks was estimated to be in cortical areas (SI, parasylvian, and MF) identified by anatomic criteria, by their response to innocuous vibratory stimulation of a finger (v-SEP), and to electrical stimulation of the median nerve (e-SEP). The maximum of the LEP N2*peak was located on the CS, medial (dorsal) to the finger motor area, as …
Lexical decision tasks in depressive patients: semantic priming before and after clinical improvement.
2002
SummaryThis study was designed to evaluate the effect of semantic priming with a lexical decision task in 22 depressed patients (DSM-III-R, 1987) and 30 control subjects. These patients were evaluated twice: first when they arrived at the hospital, and secondly, after clinical improvement. Clinical improvement was evaluated using standard depression rating scales. A lexical decision task involving semantic relations (related vs. unrelated, e.g., apple-pear) was used to evaluate the processing of semantic information. The results showed that, for the first evaluation, the depressives presented similar semantic priming to control subjects. When we compared semantic priming in the first and th…
Individuality of movements in music--finger and body movements during playing of the flute.
2013
The achievement of mastery in playing a composition by means of a musical instrument typically requires numerous repetitions and corrections according to the keys and notations of the music piece. Nevertheless, differences in the interpretation of the same music piece by highly skilled musicians seem to be recognizable. The present study investigated differences within and between skilled flute players in their finger and body movements playing the same piece several times on the same and on different days. Six semiprofessional and four professional musicians played an excerpt of Mozart’s Flute Concerto No. 2 several times on three different days. Finger and body movements were recorded by …
Visuospatial deficits in schizophrenia: central executive and memory subsystems impairments
2002
Object and spatial visual working memory are impaired in schizophrenic patients. It is not clear if the impairments reside in each memory subsystem alone or also in the central executive component that coordinates these processes. In order to elucidate which memory component is impaired, we developed a paradigm with single spatial and object working memory tasks and dual ones with two different delays (5 and 30 s). Fifteen schizophrenic patients and 14 control subjects performed these tests. Schizophrenic patients had a poorer performance compared to normal controls in all tasks and in all time delays. Both schizophrenics and controls performed significantly worse in the object task than in…
Muscular synergies during motor corrections: investigation of the latencies of muscle activities.
2010
To reduce the complexity of muscular control, a small number of muscular activations are combined to produce an infinity of movements. This concept of muscle synergies has been widely investigated, mainly by means of principal component analyses (PCA) in the case of unperturbed movements. However, reaching movements can be altered at any time if the target location is changed during their execution. In this case, PCA does not precisely measure the latencies of muscles activities. We develop here a simple method to investigate how a random target jump toward a single location induced motor corrections in the whole musculature by precisely determining the latencies of muscle activities during…
Oculopharyngeal muscular dystrophy in a northern German family linked to chromosome 14q, and presenting carnitine deficiency
1997
We report the evaluation of oculopharyngeal muscular dystrophy (OPMD) in a large northern German family, which can be traced back six generations and is unrelated to French-Canadian families. The symptoms in this family start at about 50 years of age and include dysphagia, bilateral ptosis, and in some cases a slowly progressive atrophy and weakness of other extraocular, facial or limb girdle muscles. The muscle biopsies showed the pathognomonic ultrastructural finding of characteristic intranuclear filaments. Linkage analysis confirmed that this family is also linked to chromosome 14q markers. Haplotype analysis revealed that a unique haplotype segregates with the disease which is differen…
Effects of emotional picture viewing on voluntary eye blinks
2014
Eyeblinks, whether reflexive or voluntary, play an important role in protecting our vision. When viewing pictures, reflexive eyeblinks are known to be modulated by the emotional state induced thereby. More specifically, the hedonic valence (unpleasantness-pleasantness) induced by the picture has been shown to have a linear relationship with the amplitude of a startle blink elicited during picture viewing. This effect has been attributed to congruence between an ongoing state and task demands: an unpleasant emotional state is assumed to bias our attention towards potentially harmful stimuli, such as startle tones. However, recent research suggests that the valence-specific modulation may not…
The effect of lifelong exercise on psychomotor reaction time: a study of 38 pairs of male monozygotic twins
1998
Purpose: The aim was to study the effect of lifetime physical activity on psychomotor speed. Methods: Foot and dominant hand visual simple and choice psychomotor reaction times were studied among monozygotic twins (38 pairs) aged 35-69, discordant for lifetime exercise histories. Results: There was a trend that some components of psychomotor reaction time were faster for frequent than for occasional exercisers. but the findings were not consistent for the hand and feet. After controlling for occupational physical activity, only choice decision time for the hand (26 ms, P < 0.01) and choice reaction time for the contralateral foot (51 ms, P < 0.05) both remained 7% faster. There was no trend…