Showing papers by "Mark Hallett published in 1980"
TL;DR: It is suggested that a normal role of the basal ganglia in movement is to energize the appropriate muscles required to make the movement.
Abstract: Patients with Parkinson's disease were asked to make ballistic elbow flexion movements of 10, 20 and 40 degrees. Normal subjects made all these movements in the same amount of time with a single 'triphasic' EMG pattern of successive bursts in biceps, triceps and biceps. Almost all the patients made some movements requiring additional cycles of alternating biceps and triceps activity. Most of the patients exhibited at least one example of a longer movement taking more cycles than a shorter movement. It is argued that this behaviour explains previous kinematic analyses of movement in patients with Parkinson's disease and represents a physiological mechanism of bradykinesia. In part on the basis of the data presented here, it is suggested that a normal role of the basal ganglia in movement is to energize the appropriate muscles required to make the movement.
707 citations
TL;DR: It is concluded that a sequence of inspiratory muscle activation is present in humans and is more apparent during sleep and during CO2-induced hyperpnea than during wakefulness.
Abstract: Animal studies have shown activation of upper airway muscles prior to inspiratory efforts of the diaphragm. To investigate this sequence of activation in humans, we measured the electromyogram (EMG) of the alae nasi (AN) and compared the time of onset of EMG to the onset of inspiratory airflow, during wakefulness, stage II or III sleep (3 subj), and CO2-induced hyperpnea (6 subj). During wakefulness, the interval between AN EMG and airflow was 92 +/- 34 ms (mean +/- SE). At a CO2 level of greater than or equal to 43 Torr, the AN EMG to airflow was 316 +/- 38 ms (P < 0.001). During CO2-induced hyperpnea, the AN EMG to airflow interval and AN EMG magnitude increased in direct proportion to CO2 levels and minute ventilation. During stages II and III of sleep, the interval between AN EMG and airflow increased when compared to wakefulness (P < 0.005). We conclude that a sequence of inspiratory muscle activation is present in humans and is more apparent during sleep and during CO2-induced hyperpnea than during wakefulness.
217 citations
TL;DR: Three patients with subacute combined degeneration of the spinal cord due to vitamin B12 deficiency showed a characteristic pattern of abnormalities on neurophysiological tests which corresponded to the clinical signs and symptoms, shedding light on the pathology of this disorder.
59 citations
TL;DR: The type of bladder and sphincter dysfunction found in eight children wit spinal dysraphism and the modes of therapy employed are discussed.
47 citations
TL;DR: V voiding cystourethrography only reveals narrowing of the urethra in the region of the external sphincter, but when it is combined with urodynamic evaluation, the dynamics of the function of the spHincter can be defined and a rational approach to treatment planned.
Abstract: Narrowing of the urethra in the region of the external sphincter as seen during voiding cystourethrography has routinely been termed sphincter spasm. This diagnosis was found to be incorrect in a significant percentage of boys with myelodysplasia. Thirty boys with myelodysplasia and dysfunction of the lower urinary tract, in whom voiding cystourethrography revealed narrowing in the area of the external sphincter, underwent urodynamic evaluation. Incoordination of the bladder and the sphincter (sphincter spasm) was found in only 16 (52%). In the other 14 (48%), there was either relaxation of the sphincter or absent electrical activity; atrophy and fibrosis of the striated muscle of the external sphincter (documented in six patients) probably resulted from chronic denervation. Thus, voiding cystourethrography only reveals narrowing of the urethra in the region of the external sphincter. However, when it is combined with urodynamic evaluation, the dynamics of the function of the sphincter can be defined and a rational approach to treatment planned.
11 citations