Trains of 100 to 200 stimuli result in F discharges from less than one half of motor units of hand muscles. The maximum observed F discharge frequency was 10%. There was no relation between the surface voltage of motor unit potentials and the frequency of F discharge. The motor unit potentials of larger surface voltage were recruited at higher stimulus intensity levels, usually supramaximal for...

Conduction in the lateral popliteal nerve of the baboon was studied during the course of Wallerian degeneration. Six nerves were examined. In each case the muscle response to nerve stimulation and the ascending nerve action potential were recorded daily until the nerve became inexcitable. The muscle response to nerve stimulation disappeared after four to five days, but ascending nerve action po...

Human reaction times during sensory-motor tasks vary considerably. To begin to understand how this variability arises, we examined neuronal populational response time variability at early versus late visual processing stages. The conventional view is that precise temporal information is gradually lost as information is passed through a layered network of mean-rate "units." We tested in humans w...

A core assumption underlying mental chronometry is that more complex tasks increase cortical processing, prolonging reaction times. In this study we show that increases in task complexity alter the magnitude, rather than the latency, of the output for a circuit that rapidly transforms visual information into motor actions. We quantified visual stimulus-locked responses (SLRs), which are changes...

Recording of median and ulnar digital sensory nerve action potentials in normal subjects showed that the ratio of the median (index finger) to ulnar (little finger) potential amplitude was consistently greater than one. In 15 patients with the carpal tunnel syndrome (seven bilateral) this ratio was found to be less than one for all but two of the 22 clinically affected hands, including three of...

This study explored in humans the role of the posterior parietal cortex (PPC) in saccades, vergence, and combined saccade-vergence movements by means of transcranial magnetic stimulation (TMS). TMS was applied to the right PPC at 80 ms, 90 ms, or 100 ms after target onset in experiment 1, and to the left PPC in experiment 2. Control experiments were also run in which TMS was applied over the pr...

BACKGROUND We evaluated the epidural administration of tezampanel, a non-N-methyl-d-aspartate receptor antagonist, in a rat model for postoperative pain. We sought to determine if this drug affects nociception when administered epidurally by testing its effects on responses to heat in normal rats. The effects of epidural tezampanel on pain-related behaviors in rats that underwent plantar incisi...

OBJECTIVE To examine mechanisms controlling the stapedial reflex in patients with amyotrophic sclerosis (ALS). METHODS The stapedial reflex was examined using impedance audiometry in 38 patients with sporadic ALS and in 25 age matched controls. RESULTS All patients showed normal reflex decay test results. There were no significant differences between patients with ALS and control subjects i...

PRIMARY OBJECTIVE To study whether transcallosal inhibition (TCI) can evaluate the severity of traumatic brain injury (TBI). RESEARCH DESIGN Case-control study. METHODS AND PROCEDURES Twenty patients with a chronic TBI and 20 control subjects were studied. The following transcranial magnetic stimulation parameters were checked; resting motor threshold, central motor latency times, onset lat...