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Biomedical subjects

D Regan

Publications and source records attributed to D Regan.

At least 163 records · Page 9Linked to original sources
PubMed1981

Auditory brainstem responses in postconcussion syndrome.

Evidence that head injuries can shear nerve fibers and end bulbs in the tracts between the diencephalon and brainstem led us to hypothesize that auditory brainstem responses might be abnormal in patients with postconcussion syndrome. We recorded brainstem responses in 11 patients and 12 control subjects. Comparing the two populations, our chief finding was that the patients showed significant delays for wave 3. This finding indicates organic changes involving a region at least as central as the superior olivary complex, thus refuting many authors' claims that the syndrome is entirely psychogenic.

Adult↗
PubMed1981

Abnormal adaptation of visual contrast sensitivity in multiple sclerosis patients.

Some multiple sclerosis patients with 20/20 acuity complain of poor vision. In a previous report we accounted for this in our patient group by showing that multiple sclerosis had caused a depression of contrast sensitivity while sparing visual acuity. In this study we investigated whether some of this measured depression might be due to abnormally rapid or severe adaptation during the test procedure rather than a true permanent loss. Our finding was opposite to this supposition: adaptation was normally slight and/or slow. Depressed contrast sensitivity was not well correlated with abnormal adaptation to contrast. In patients whose contrast sensitivity losses were restricted to a band of spatial frequencies, we found no evidence that abnormalities of contrast adaptation were restricted to this same spatial frequency band. Further evidence of dissociation between abnormal contrast sensitivity and abnormal contrast adaptation is that some patients with normal contrast sensitivity showed abnormally small adaptation.

Adaptation, Ocular↗
PubMed1981

Correlations between visual test results and flying performance on the advanced simulator for pilot training (ASPT).

Looking for visual differences in pilots to account for differences in flying performance, we tested five groups of subjects: Air Force primary student jet pilots, graduating (T38 aircraft) students, Air Force pilot instructors, and two control groups made up of experienced nonpilot aircrew and nonflying civilians. This interim report compares 13 different visual test results with low-visibility landing performance on the Air Force Human Resources Laboratory ASPT simulator. Performance was assessed by the number of crashes and by the distance of the aircraft from the runway threshold at the time of the first visual flight correction. Our main finding was that, for student pilots, landing performance correlated with tracking performance for a target that changed size (as if moving in depth) and also with tracking performance for a target that moved sideways. On the other hand, landing performance correlated comparatively weakly with psychophysical thresholds for motion and contrast. For student pilots, several of the visual tests gave results that correlated with flying grades in T37 and T38 jet aircraft. Tracking tests clearly distinguished between the nonflying group and all the flying groups. On the other hand, visual threshold tests did not distinguish between nonflying and flying groups except for grating contrast, which distinguished between the nonflying group and the pilot instructors. The sideways-motion tracking task was sensitive enough to distinguish between the various flying groups.

Adult↗
PubMed1980

Temporal selectivity of changing-size channels.

Changing-size channels tuned to the oscillation frequency are excited by a stimulus square whose size oscillates at a fixed frequency. In the 0.25-16 Hz frequency band there are at least three kinds of changing-size channels tuned to different frequencies.

Humans↗