58080
document
Temporal expectation in focal hand dystonia . Patients with writer 's cramp present sensory and representational abnormalities relevant to motor control , such as impairment in the temporal discrimination between tactile stimuli and in pure motor imagery tasks , like the mental rotation of corporeal and inanimate objects . However , only limited information is available on the ability of patients with dystonia to process the time-dependent features ( e.g . speed ) of movement in real time . The processing of time-dependent features of movement has a crucial role in predicting whether the outcome of a complex motor sequence , such as handwriting or playing a musical passage , will be consistent with its ultimate goal , or results instead in an execution error . In this study , we sought to evaluate the implicit ability to perceive the temporal outcome of different movements in a group of patients with writer 's cramp . Fourteen patients affected by writer 's cramp in the right hand and 17 age- and gender-matched healthy subjects were recruited for the study . Subjects were asked to perform a temporal expectation task by predicting the end of visually perceived human body motion ( handwriting , i.e . the action performed by the human body segment specifically affected by writer 's cramp ) or inanimate object motion ( a moving circle reaching a spatial target ) . Videos representing movements were shown in full before experimental trials ; the actual tasks consisted of watching the same videos , but interrupted after a variable interval ( 'pre-dark ' ) from its onset by a dark interval of variable duration . During the 'dark ' interval , subjects were asked to indicate when the movement represented in the video reached its end by clicking on the space bar of the keyboard . We also included a visual working memory task . Performance on the timing task was analysed measuring the absolute value of timing error , the coefficient of variability and the percentage of anticipation responses . Patients with writer 's cramp exhibited greater absolute timing error compared with control subjects in the human body motion task ( whereas no difference was observed in the inanimate object motion task ) . No effect of group was documented on the visual working memory tasks . Absolute timing error on the human body motion task did not significantly correlate with symptom severity , disease duration or writing speed . Our findings suggest an alteration of the writing movement representation at a central level and are consistent with the view that dystonia is not a purely motor disorder , but it also involves non-motor ( sensory , cognitive ) aspects related to movement processing and planning .
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Intervention_Educational
temporal outcome
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Intervention_Psychological
temporal expectation task
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Intervention_Psychological
Videos representing movements
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Outcome_Mental
visual working memory task
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Outcome_Mental
Absolute timing error
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Participant_Condition
focal hand dystonia
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Participant_Condition
writer 's cramp
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Participant_Condition
dystonia
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Participant_Condition
writer 's cramp
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Participant_Sample-size
Fourteen
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Participant_Sample-size
17
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Participant_Condition
writer 's cramp