title: Luminance and chromatic modulation sensitivity of macaque ganglion cells and human observers.
abstract: We measured the sensitivity of macaque ganglion cells to luminance and chromatic sinusoidal modulation. Phasic ganglion cells of the magnocellular pathway (M-pathway) were the more sensitive to luminance modulation, and tonic ganglion cells of the parvocellular pathway (P-pathway) were more sensitive to chromatic modulation. With decreasing retinal illuminance, phasic ganglion cells' temporal sensitivity to luminance modulation changed in a manner that paralleled psychophysical data. The same was true for tonic cells and chromatic modulation. Taken together, the data suggest strongly that the cells of the M-pathway form the physiological substrate for detection of luminance modulation and the cells of the P-pathway the substrate for detection of chromatic modulation. However, at high light levels, intrusion of a so-called luminance mechanism near 10 Hz in psychophysical detection of chromatic modulation is probably due to responses in the M-pathway, arising primarily from a nonlinearity of cone summation. Both phasic and tonic ganglion cells responded to frequencies higher than can be psychophysically detected. This suggests that central mechanisms, acting as low-pass filters, modify these cells' signals, though the corner frequency is lower for the P-pathway than for the M-pathway. For both cell types, the response phase at different frequencies was consistent with the cells' description as linear filters with a fixed time delay.
authors.affiliation: Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Federal Republic of Germany.
authors.forename: B B
authors.initials: BB
authors.lastname: Lee
authors.forename: J
authors.initials: J
authors.lastname: Pokorny
authors.forename: V C
authors.initials: VC
authors.lastname: Smith
authors.forename: P R
authors.initials: PR
authors.lastname: Martin
authors.forename: A
authors.initials: A
authors.lastname: Valberg
mesh_terms: D000818:Animals; D002138:Calibration; D003118:Color Perception / Q000502:physiology*; D015350:Contrast Sensitivity / Q000502:physiology*; D004594:Electrophysiology; D006801:Humans; D008027:Light; D008252:Macaca fascicularis; D010775:Photic Stimulation / Q000295:instrumentation; D011601:Psychophysics; D012165:Retinal Ganglion Cells / Q000502:physiology*; D012684:Sensory Thresholds / Q000502:physiology; D014795:Visual Pathways / Q000166:cytology / Q000502:physiology