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Biomedical subjects

D Regan

Publications and source records attributed to D Regan.

243 records · Page 14Linked to original sources
PubMedDate not supplied

A comparison of the 40-Hz response in man, and the properties of macaque ganglion cells.

Visually evoked field potentials in human subjects and single-cell responses from retinal ganglion cells in the macaque monkey were compared in closely similar stimulus situations. The classical heterochromatic flicker photometry (HFP) technique was used to measure spectral sensitivity in man, both psychophysically and by recording the 40-Hz response, and to measure the spectral sensitivity of magnocellular (MC-) pathway cells of the macaque. The three measures gave closely similar spectral-sensitivity curves. Close agreement between the three measures was also found when the variable-modulation HFP technique was used to measure spectral sensitivity. When the relative phase between red and green lights was varied, the point of minimum subjective flicker for human observers was close to a sharp minimum found in the amplitude of the 40-Hz response in human and was also close to a minimum in the response of MC-pathway neurons in the monkey. The human 40-Hz response saturated at between 10 and 30% modulation depth, and so did the response of MC-pathway cells in the monkey. The 16-Hz response in human showed none of the above correlations with MC-pathway properties. On the other hand, parvocellular (PC-) pathway cells responded vigorously to constant-luminance, chromatic modulation, at frequencies higher than can be detected by human observers. The human 16-Hz response also was strong in that stimulus situation. In addition, the response of PC-pathway cells on increasing modulation depth showed little saturation, and this behaviour was paralleled by the human 16-Hz response.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Spatial orientation in aviation: visual contributions.

Misjudgment of spatial orientation is reported to be an important factor in a substantial proportion of aviation accidents. The likelihood of such misjudgment is particularly high when there are conflicting interactions between labyrinthine and visual signals. In a manoeuvering aircraft, visual information is often a crucial factor in the pilot's ability to judge the aircraft's altitude and position with respect to external and terrain features. A body of research evidence supports the following conceptual framework. (1) The human visual system processes a limited number of visual dimensions almost independently of each other (for example, colour, luminance, spatial frequency, orientation, changing size, motion in depth, time to contact). (2) Each of these selective sensitivities shows considerable intersubject variability. (3) Intersubject variability is far from perfectly correlated across the set of selective sensitivities. This paper discusses the relevance of this framework for predicting, first the specific situations in which visual judgments are most likely to occur and, second, which individual pilots are most likely to make the visual misjudgments.

Accidents, Aviation↗