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Biomedical subjects

C R Cavonius

Publications and source records attributed to C R Cavonius.

At least 37 records · Page 2Linked to original sources
PubMed1975

Contrast sensitivity of individual colour mechanisms of human vision.

1. Contrast sensitivity functions of isolated colour mechanisms were measured at spatial frequencies from 0-2 to 32 c/deg. The contrast sensitivity vs. spatial-frequency functions of the red (pi5) and green (pi4) mechanisms are similar, while the blue (pi3) mechanism has lower absolute sensitivity and lower resolving power. Isolation of a single mechanism never increases its maximum sensitivity. 2. The shape of the contrast sensitivity function of a colour mechanism is established within the mechanism. Little if any inhibitory interaction takes place among colour mechanisms. 3. Differences that have been reported between the sensitivities of the red and green mechanisms, as well as the apparent "supersensitivity" of the isolated green mechanism, may be artifacts that result from the extrapolation procedures that were used to estimate the absolute sensitivities of the colour mechanisms.

Adaptation, Ocular↗
PubMed1973

Relationships between luminance and visual acuity in the rhesus monkey.

1. The ability of rhesus monkeys to detect the gap in Landolt ring test-objects that were presented against background luminances between 5 x 10(-5) cd/m(2) and 5 x 10(3) cd/m(2) was compared with similar human data.2. At high luminance-levels the acuity of human observers is slightly better than that of rhesus, but rhesus have better acuity at scotopic luminance-levels. Both species have distinct photopic and scotopic acuity functions that cross at 6 x 10(-3) cd/m(2).3. The threshold for light detection is estimated to be the same for both species when specified in quanta incident on the retina.4. It is concluded that the receptor and neural mechanisms that mediate visual-acuity function similarly in rhesus and man, and that the differences in acuity that were measured in the two species may be attributed to optical rather than to physiological factors.

Animals↗
PubMed1971

Alpha and kappa electroencephalogram activity in eyeless subjects.

Several reports have cast doubt on the cerebral origin of alpha and kappa electroencephalogram activity by charging that they are artifacts related to eye activity. Data are cited which eliminate the corneoretinal potential of the eyeball, tremor of the extraocular muscles, eye position, accommodation, and eye flutter as sources of alpha and kappa electroencephalogram activity. A subject with both eyes removed showed normal alpha and kappa electroencephalogram activity. Marked left-right differences in alpha activity were not found in one-eyed subjects whose eyes and extraocular muscles were completely removed on one side.

Adult↗