[A telemetric method of measuring motor activity in behavioral analysis. Technical description and first results in children with behavior disorders]

[Delayed initiation of voluntary movements after pyramidal lesions in man (author's transl)]

The reaction times for rapid movements in muscles of arm and leg were measured in 20 patients with unilateral lesions of the motor cortex and the internal capsule. Rapid unilateral and bilateral movements after an acoustic signal (click) on the pyramidally paretic side were compared with the normal side. In these patients and in 10 normal subjects, electromyographic and mechanical recordings from symmetrical muscles of both sides were compared. 2. All patients with pyramidal lesions showed in the case of unilateral movements a marked prolongation of motor latency in the affected muscles: compared to the normal side, the movement started 30-160 msec later in muscles contralateral to the lesion of the motor cortex. In contrast, normal subjects showed equal latencies on both sides with maximal differences of 10-20 msec. 3. When movements were executed bilaterally the latency prolongation in the pyramidally paretic muscles was markedly diminished or disappeared in later stages. In most patients the bilateral movements started simultaneously in the normal and the paretic muscles, except in 5 recent lesions of the contralateral motor cortex. 4. The significance of the findings is discussed in terms of the function of the human motor cortex in starting and controlling voluntary movements. It is assumed that the disappearance of latency prolongation when movements are executed bilaterally in patients with unilateral pyramidal lesions can be best explained by homolateral projections of uncrossed pyramidal fibres to the motoneurones. 5. These results, and other observations, suggest that the motor cortex starts and controls voluntary movements via rapidly conducting pyramidal fibres to the motoneurones. This occurs after a preprogramming and a readiness posture is established by other cerebral structures. The prolongation of motor latencies after motor cortex lesions is probably due to a disturbance in the rapidly conducting cortico-spinal projections to spinal motoneurones and interneurones.

Hyperactive behavior and EEG arousal reactions in children

EEG arousal reactions and parameters of spontaneous EEG activity were studied in two extreme groups of behavior problem children (11 hyperactives and 11 non-hyperactives), selected on the basis of a rating of motor restlessness the core symptom of the "hyperactivity syndrome". The EEG was recorded in three reaction time experiments: a tone light conditioning paradigm and two series with random stimulation. An automatic analysis of EEG parameters was employed to describe the time functions of alpha amplitudes in the single trial. The main findings are: 1. In periods free from stimulation, hyperactive children have higher alpha and beta amplitudes, more alpha waves and a smaller amount of beta waves. This indicates a lower state of EEG arousal in the hyperactives. 2. The amplitude reduction to tone (in the single trial) develops more slowly in the hyperactive group. This group difference increases over the experimental situations. 3. The arousal responses to tone, in terms of the level of maximum amplitude reduction, become comparably weaker in the hyperactives across the experiments. 4. Under all experimental conditions the hyperactives exhibit shorter arousal responses to the light stimulus than the non-hyperactive children. 5. Reaction time performance of the groups is clearly different, hyperactives showing the longer latencies. 6. Although conditional changes in the arousal reactions to both stimuli are reliably demonstrable in all children, the groups show no difference in the corresponding measures. These findings are discussed under the aspects of activation and of attention behavior of the subjects.