Biomedical subjects

J A Matsen-Twisdale

Publications and source records attributed to J A Matsen-Twisdale.

3 recordsLinked to original sources

PubMed1979

Visual evoked potentials and signal detection following a marathon race.

Five marathon runners participated in a visual sustained attention experiment 1 week prior to a competitive martathon race and from 1.5 to 8.5 h following the race. The task was designed to help assess changes in central nervous system function by examinining both behavioral deficits and electroencephalogram (EEG) visual evoked potentials as a function of the race. A significant increase in heart rate was observed during the behavioral task. No changes in any of the wave forms of the EEG visual evoked response were observed during the vigilance task as a function of the race. Sustained visual attention responses were unchanged for correct detections, but post-marathon performance gave significantly fewer false positive responses. The results provided evidence that central nervous system dysfunction was not observed following the completion of a competitive marathon race.

Adult↗

PubMed1979

Pulmonary function and maximum exercise responses following acute ozone exposure.

We examined changes in pulmonary function during resting exposure to concentrations of ozone at 0.75, 0.50, 0.25, and 0.00 parts/million (ppm), and determined the effect these exposures had on a subsequent maximum exercise test using filtered air. In order to determine if recovery of pulmonary function would be facilitated by increased ventilation due to maximum exercise, a control condition was conducted with subjects resting for a period equivalent to the maximum exercise condition. Eight males and five females participated in eight different conditions in order to answer these two questions. Resting 2-h exposure to 0.75 and 0.50 ppm ozone caused significant decrements in forced vital capacity of 10% and 5%, respectively. However, 0.00 and 0.25 ppm ozone induced no pulmonary decrement. None of the pollutant conditions reduced subsequent maximum exercise performance (ml O2.min-1.kg-1, heart rate, and total performance time). The pulmonary function responses after the maximum capacity test returned to pre-ozone values for the 0.50 ppm condition, but were still significantly decreased for the 0.75 ppm condition. The increased ventilatory exchanges from maximum exercise did not facilitate the return of pulmonary function. It appeared that increased ventilation during ozone exposure plays a significant role only in inducing pulmonary function decrement, but not in facilitating the return of pulmonary function to normal values.

Adult↗

PubMed1979

Auditory and visual sustained attention during ozone exposure.

Experiments were conducted to determine the effects of different concentrations of ozone at 0.00, 0.25, 0.50, and 0.75 parts/million (ppm) on sustained visual and auditory attention tasks (vigilance performance). When the rate of signals to nonsignals was low, approximately 1 out of 30, ozone in concentrations as high as 0.75 ppm did not alter performance to either visual or auditory tasks. However, when the ratio of signals to non-signals was increased, a deficit in performance beyond that of the normal vigilance decline was observed during the 0.75 ppm ozone exposure. However, no changes in false positive responses occurred. The results were interpreted within the framework of an arousal hypothesis, suggesting that high concentrations of ozone may produce overarousal.

Adult↗