1,720,987 research outputs found
Beta band frequency differences between motor and frontal cortices in reaching movements
No full textCervical dystonia affects aimed movements of non dystonic segments
No full textPatients with focal dystonia exhibit proprioception
abnormalities that can lead to kinematic deficits. Proprioceptive
abnormalities are present in both symptomatic and
asymptomatic body parts of dystonic patients. To ascertain
whether in patients with idiopathic cervical dystonia (CD)
movements performed with nondystonic segments display kinematic
abnormalities, we studied trajectory formation of out
and back arm reaching movements in 10 patients with CD
(before and 3 weeks after treatment with Botulinum toxin)
and in 10 age-matched controls. Before treatment, patients
with CD showed significant trajectory abnormalities when
compared with normal controls. Patients’ trajectories were
more curved with asymmetrical temporal velocity profiles as
well as increased hand path areas, and had longer reversal
lags between the out and back segments. Treatment with botulinum
toxin improved all the kinematic parameters. These
results suggest that in patients with CD, movements performed
with nondystonic segments are abnormal. The kinematic
abnormalities are likely to derive from long-standing
defective integration of the proprioceptive input, which, in
turn, causes general changes in the internal models of limb
dynamics. It is plausible that treatment with botulinum toxin
partially restores proprioceptive processing and thus, such internal
model
Recovery of motor performance deterioration induced by a demanding finger motor task does not follow cortical excitability dynamics.
No full textIncreased reaction time predicts visual learning deficits in Parkinson's disease.
No full textTo determine whether the process involved in movement preparation of patients in the early stages of Parkinson's disease (PD) shares attentional resources with visual learning, we tested 23 patients with PD and 13 healthy controls with two different tasks. The first was a motor task where subjects were required to move as soon as possible to randomly presented targets by minimizing reaction time. The second was a visual learning task where targets were presented in a preset order and subjects were asked to learn the sequence order by attending to the display without moving. Patients with PD showed higher reaction and movement times, while visual learning was reduced compared with controls. For patients with PD, reaction times, but not movement times, displayed an inverse significant correlation with the scores of visual learning. We conclude that visual declarative learning and movement preparation might share similar attentional and working memory resources
Mapping of event-related potentials to auditory and visual odd-ball paradigms.
No full textThis paper reports the results of recordings and maps of event-related potentials (ERPs) obtained in normal subjects, patients with Alzheimer's disease (AD), progressive supranuclear palsy, confusional states, and in subjects with homonymous hemianopsia. ERPs were recorded from 19 scalp electrode derivations using both visual and acoustic paradigms. In normal subjects, the topographical distribution of all ERP components is described in detail. In 45% of AD patients, ERPs were normal; in 35%, although present, ERP components were delayed, while in the other 20% the N2 and P3 peaks could not be recorded. In patients with progressive supranuclear palsy, the normal ERP sequence was not identified. Our findings in normals and in hemianopic patients suggest that the early modulation of stimulus-related potentials could be located in primary associative areas, and that N2, P3a, P3b, SW should have different origins
Learning and consolidation of visuo-motor adaptation in Parkinson’s disease
No full textWe have previously shown in normal subjects that motor adaptation to imposed visual rotation is significantly enhanced when tested few days later. This occurs through a process of sleep-dependent memory consolidation. Here we ascertained whether patients with Parkinson's disease (PD) learn, improve, and retain new motor skills in the same way as normal subjects. We tested 16 patients in early stages of PD and 21 control subjects over two days. All subjects performed reaching movements on a digitizing tablet. Vision of the limb was precluded with an opaque screen; hand paths were shown on the screen with the targets' position. Unbeknownst to the subjects, the hand path on the screen was rotated by 30 degrees . In experiment 1, patients taking dopaminergic treatment and controls adapted to rotation with targets appearing in an unpredictable order. In experiment 2, drug-naïve patients and controls adapted to rotation in a less challenging task where target's appearance was predictable. Patients and controls made similar movements and adapted to rotation in the same way. However, when tested again over the following days, controls' performance significantly improved compared to training, while patients' performance did not. This lack of consolidation, which is present in the early stages of the disease and is independent from therapy, may be due to abnormal homeostatic processes that occur during sleep
Spontaneous movement tempo is influenced by observation of rhythmical actions
No full textObservation of people performing movements facilitates motor planning, execution and memory formation.
Tempo, a crucial aspect involved in the execution of rhythmic movements, is normally perceived
and learned through auditory channels. In this work, we ascertained whether: first, the frequency of
self-paced finger movements (SPMs), which in normal subjects is around 2 Hz, is modified by prior
observation of movements performed at either 1 or 3 Hz; second, such changes are lasting; third, there
is an effect of time interval between observation and performance. We finally determined the effect
of providing explicit information about the upcoming motor task. Seventy-two normal subjects (12
groups) performed a simple finger sequence at different intervals after observation of videos of either
landscapes or finger opposition movements. Both with and without information about the upcoming
task, observation influenced the tempo of SPMs and led to memory formation. With knowledge
of the upcoming task, such changes occurred at all observation–execution intervals, while without
instructions, changes took place only when SPMs were performed immediately after observation. Compared
to explicit instructions, the absence of instructions produced tempo’s changes that more closely
resembled the observed rhythms. We conclude that learning requires a prompt comparison between
visual and sensorimotor representations of movements; moreover, learning with explicit instructions
is more efficient, as activity in both the dorsal and ventral streams might be potentiated by the
chatecholaminergic attentional systems that promote long-term potentiation. These results provide
the bases for novel neurorehabilitation strategies in terms of temporal re-organization of movemen
The serial reaction time task revisited: a study on motor sequence learning with an arm-reaching task
No full text
- …
