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SPECTRAL SENSITIVITY OF SINGLE UNITS IN THE OPTIC TECTUAI OF THE GOLDFISH
Author(s) -
Jacobson Marcus
Publication year - 1964
Publication title -
quarterly journal of experimental physiology and cognate medical sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0033-5541
DOI - 10.1113/expphysiol.1964.sp001744
Subject(s) - spectral sensitivity , maxima , optics , wavelength , sensitivity (control systems) , photopic vision , action spectrum , absorption spectroscopy , absorption (acoustics) , analytical chemistry (journal) , chemistry , physics , chromatography , art , retina , photochemistry , electronic engineering , performance art , art history , engineering
Action potentials evoked by a small light in the visual field were recorded from single units in the optic tectum of the goldfish. The relative spectral sensitivity of these responses was measured by determining the threshold energy of the stimulus light at 22 wavelengths from 341 to 779 mµ. After dark adaptation the spectral sensitivity of "on", "off" and "on‐off" units was the same, with a maximum at about 533 mµ and fitted the absorption spectrum of porphyropsin. After light adaptation some "on" and some "off" units had a spectral sensitivity curve which fitted the absorption spectrum of cyanopsin with a maximum at about 620 mµ. Most units had a narrow photopic spectral sensitivity curve: in some units there was a single maximum, usually in the range 605‐651 mµ. but in some "on‐off" units the maximum sensitivities of "on" and of "off" responses were different. There were three classes of these units: R‐G units (sensitivity maxima at 630‐651 mµ and 497‐517 mµ), R‐B units (maxima 605‐651 mµ and 462 ±14 mµ) and Y‐B units (maxima 552‐605 mµ and 462±14 mµ). The neutral point, at which "on" and "off" responses had the same sensitivity, was at 552‐584 mµ in R‐G units, at 517‐552 mµ in R‐B units and at 497‐517 mµ in Y‐B units. The results indicate that the goldfish has a rod pigment with its absorption maximum at about 533 mµ, and that there are at least two cone pigments with absorption maxima at about 467 mµ and 620 mµ. It is suggested that antagonism between two sets of cones, each set containing one of three pigments with absorption maxima at 467, 533 and 620 mµ could account for the observed sensitivity maxima and neutral points of R‐G, R‐B and Y‐B units.