RESUMEN
OBJECTIVE: To explore whether stroke patients exhibit increases in motor excitability during action observation, whether differences exist between the affected and non-affected sides, and between pure motor strokes and predominantly sensory strokes. METHODS: In 18 patients (10 pure motor strokes, 8 predominantly sensory strokes, < 6 months after the stroke) transcranial magnetic stimulation was used to test motor excitability while the patients viewed a video showing a hand performing pinch grips. Transcranial magnetic stimulation pulses were applied at 120% of the individual motor threshold at rest, as obtained from the affected hemisphere. Recordings were taken simultaneously from the first dorsal interosseous muscle of both hands. Motor performance was evaluated with the Box and Block Test. RESULTS: Transcranial magnetic stimulation-evoked muscle responses obtained from the affected and the unaffected sides were significantly higher during action observation than during rest (p = 0.024 and p = 0.004, respectively). This effect was significantly stronger when measuring the same hand as the one viewed in the video (p = 0.019). No difference was found between motor and sensory strokes. In 11 patients there was an action observation-associated increase in the amplitudes of motor evoked potentials in the affected side. In 15 patients there was an action observation-associated increase in motor evoked potentials amplitudes in the unaffected side. CONCLUSION: The results are potentially relevant for the use of action observation as a treatment strategy.
Asunto(s)
Potenciales Evocados Motores/fisiología , Corteza Motora/fisiopatología , Fuerza de Pellizco/fisiología , Accidente Cerebrovascular/fisiopatología , Adulto , Anciano , Electromiografía , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estimulación Magnética TranscranealRESUMEN
OBJECTIVE: This study examined the temporal congruency between real and imagined movements and explored intermanual transfer effects in healthy subjects. METHODS: Seventy-six right-handed healthy subjects were allocated to three age groups and tested with a modified version of the Box and Block Test (BBT). We focussed on two aspects. First, the BBT was evaluated with respect to its ability to assess MC. Second, we were interested whether performance of motor imagery (MI) and real execution with one hand would modify performance with the other hand. To explore MC, we measured motor execution (ME) time as the time needed to perform the BBT, and MC time as the time difference between ME and the time needed for imagination of task execution. The BBT was performed with both hands consecutively to study transfer effects from one hand to the other and then repeated with the first hand for practice effects. RESULTS: The age group with the oldest subjects exhibited a slower BBT performance and a less precise MC than the other 2 age groups. Irrespective of the age, MC abilities could be transferred to the other hand, whereas ME only improved when repeating the task with the same hand. CONCLUSIONS: The BBT was able to demonstrate an age-related decline of dexterity and MC. Intermanual transfer of MI abilities occurred even after a single run.
Asunto(s)
Imaginación , Destreza Motora/fisiología , Movimiento , Adolescente , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Análisis de Varianza , Femenino , Humanos , Masculino , Persona de Mediana Edad , Análisis y Desempeño de Tareas , Factores de Tiempo , Adulto JovenRESUMEN
OBJECTIVE: To explore motor excitability changes induced by disobedience and feigning-like behaviour. METHODS: Healthy subjects participated in motor imagery tasks. They imagined either a maximum muscle relaxation (condition 1) or a pinch grip (condition 2). In other trials, they were instructed to disobey the command to imagine a pinch grip. Instead, they should either imagine a maximum muscle relaxation (condition 3) or think of something else which they could choose freely (condition 4). Transcranial magnetic stimulation was used to explore motor excitability during the different tasks. Motor evoked potential amplitudes were expressed as percentage of the task-free control condition (condition 5). RESULTS: Imagination of a pinch grip enhanced motor excitability, imagery of maximum muscle relaxation reduced motor excitability below the level of the control condition. In conditions 3 and 4, motor excitability was lower than in condition 2. However, motor excitability in condition 3 was higher than in condition 1. CONCLUSIONS: Healthy subjects successfully disobeyed the motor imagery command but failed to maintain the down-regulation of motor excitability when trying to imagine maximum muscle relaxation. SIGNIFICANCE: The results help to interpret the down-regulation of motor excitability found in patients with motor conversion disorder.
Asunto(s)
Potenciales Evocados Motores/fisiología , Fuerza de la Mano/fisiología , Imaginación/fisiología , Relajación Muscular/fisiología , Músculo Esquelético/fisiología , Tractos Piramidales/fisiología , Adulto , Electromiografía/métodos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Movimiento/fisiología , Estimulación Magnética Transcraneal/métodosRESUMEN
BACKGROUND: Motor imagery (MI) is increasingly recognized as a treatment option after stroke, but not all stroke patients are able to perform MI. OBJECTIVE: To examine if severe somatosensory deficits would affect MI ability. METHODS: The Box and Block Test (BBT) was used to evaluate mental chronometry as 1 component of MI. Two groups of stroke patients and an age-matched healthy control group (CG) were studied. Patient group 1 (n = 10, PG1) had a severe somatosensory impairment on the affected side and PG2 (n = 10) had pure motor strokes. All subjects first performed the BBT in a mental and in a real version. The time needed to move 15 blocks from 1 side of the box to the other was measured. To compare the groups independently of their performance level, a (real performance--MI)/(real performance) ratio was calculated. Corticospinal excitability was measured by transcranial magnetic stimulation at rest and while the subjects performed an imagined pinch grip. RESULTS: The CG performed the BBT faster than both patient groups, and PG1 was slower than PG2. MI ability was impaired in PG1 but only for the affected hand. Transcranial magnetic stimulation data showed an abnormally low MI-induced corticospinal excitability increase for the affected hand in PG1, but not in PG2. CONCLUSIONS: Severe somatosensory deficits impaired mental chronometry. A controlled study is necessary to clarify if these patients benefit at all from MI as an additional treatment.