scholarly journals A Corrected Formula for the Spectral Sensitivity Function in Radio Astronomy

1962 ◽  
Vol 15 (3) ◽  
pp. 445 ◽  
Author(s):  
RN Bracewell
Keyword(s):  
Spectral Sensitivity ◽  
Radio Astronomy ◽  
Sensitivity Function ◽  
Aperture Distribution ◽  
Spectral Sensitivity Function

According to Bracewell and Roberts (1954) the spectral sensitivity function .1(s) is calculated from an aerial aperture distribution .

Light-evoked contraction of red absorbing cones in the Xenopus retina is maximally sensitive to green light

1992 ◽  
Vol 8 (3) ◽  
pp. 243-249 ◽  
Author(s):  
Joseph C. Besharse ◽  
Paul Witkovsky
Keyword(s):  
Xenopus Laevis ◽  
Spectral Sensitivity ◽  
Red Light ◽  
Green Light ◽  
Sensitivity Function ◽  
Direct Mechanism ◽  
Sensitivity Experiments ◽  
Light Stimuli ◽  
The Difference ◽  
Spectral Sensitivity Function

AbstractTo test the hypothesis that light-evoked cone contraction in eye cups from Xenopus laevis is controlled through a direct mechanism initiated by the cone's own photopigment, we conducted spectral-sensitivity experiments. We estimate that initiation of contraction of red absorbing cones (611 nm) is 1.5 log units more sensitive to green (533 nm) than red (650 nm) light stimuli. The difference is comparable to that predicted from the spectral-sensitivity function of the green absorbing, principal rod (523 nm). Furthermore, 480-nm and 580-nm stimuli which are absorbed nearly equally by the principal rod have indistinguishable effects on cone contraction. We also found that light blockade of nighttime cone elongation is much more sensitive to green than to red light stimuli. Our observations are inconsistent with the hypothesis tested, and suggest that light-regulated cone motility is controlled through an indirect mechanism initiated primarily by the green absorbing, principal rod.

Tetrachromatic input to turtle horizontal cells

2001 ◽  
Vol 18 (5) ◽  
pp. 759-765 ◽  
Author(s):  
Y. ZANA ◽  
D.F. VENTURA ◽  
J.M. de SOUZA ◽  
R.D. DeVOE
Keyword(s):  
Spectral Sensitivity ◽  
Horizontal Cell ◽  
Sensitivity Function ◽  
Horizontal Cells ◽  
Chromatic Adaptation ◽  
Morphological Evidence ◽  
Cone Type ◽  
Response Method ◽  
Uv Cone ◽  
Spectral Sensitivity Function

Recent physiological experiments support behavioral and morphological evidence for a fourth type of cone in the turtle retina, maximally sensitive in the ultraviolet (UV). This cone type has not yet been included in the models proposed for connectivity between cones and horizontal cells. In this study, we examined the inputs of UV, S, M, and L cones to horizontal cells. We used the high-resolution Dynamic Constant Response Method to measure the spectral sensitivity of horizontal cells without background light and after adaptation to UV, blue (B), green (G), and red (R) light. We concluded the following: (1) Tetrachromatic input to a Y/B horizontal cell was identified. The spectral-sensitivity curves of the cell in three of the adaptation conditions were well represented by L-, M-, and S-cone functions. Adaptation to blue light revealed a peak at 372 nm, the same wavelength location as that determined behaviorally in the turtle. A porphyropsin template could be closely fitted to the sensitivity band in that region, strong evidence for input from a UV cone. (2) The spectral-sensitivity functions of R/G horizontal cells were well represented by the L- and M-cone functions. There was no indication of UV- or S-cone inputs into these cells. (3) The spectral sensitivities of the monophasic horizontal cells were dominated by the L cone. However, the shape of the spectral-sensitivity function depended on the background wavelength, indicating secondary M-cone input. Connectivity models of the outer retina that predict input from all cone types are supported by the finding of tetrachromatic input into Y/B horizontal cells. In contrast, we did not find tetrachromatic input to R/G and monophasic horizontal cells. Chromatic adaptation revealed the spectral-sensitivity function of the turtle UV cone peaking at 372 nm.

scholarly journals Spectral Sensitivity of the Common Prawn, Palaemonetes vulgaris

1968 ◽  
Vol 51 (5) ◽  
pp. 694-700 ◽  
Author(s):  
George Wald ◽  
Edward B. Seldin
Keyword(s):  
Spectral Sensitivity ◽  
Dark Adaptation ◽  
Visual Pigment ◽  
Red Light ◽  
Relative Number ◽  
Sensitivity Function ◽  
The Common ◽  
Colored Lights ◽  
Spectral Sensitivity Function ◽  
Spectral Sensitivity Curve

The vision of Palaemonetes is of particular interest in view of extensive studies of the responses of its chromatophore systems and eye pigments to light. The spectral sensitivity is here examined under conditions of dark adaptation and adaptation to bright colored lights. In each case the relative number of photons per one-fiftieth sec flash needed to evoke a constant peak amplitude (usually 25 or 50 µv) in the electroretinogram (ERG) was measured at various wavelengths throughout the spectrum. The sensitivity is the reciprocal of this number. In dark-adapted animals the spectral sensitivity curve consists of a broad, almost symmetrical band, maximal at about 540 mµ, with a shoulder near 390 mµ. Adaptation to bright red or blue light, left on continuously throughout the measurements, depresses the 540 mµ peak without notably changing its shape or position, implying that only one visual pigment operates in this region. Adaptation to red light, however, spares a violet-sensitive system, so that a high, narrow peak at 390 mµ now dominates the spectral sensitivity function. The 540 and 390 mµ peaks are apparently associated with different visual pigments; and these seem to be segregated in different receptor systems, since the associated ERG's have markedly different time constants. It is suggested that these two sensitivity bands may represent the red- and violet-sensitive components of an apparatus for color differentiation.

Cone contributions to the photopic spectral sensitivity of the zebrafish ERG

1998 ◽  
Vol 15 (6) ◽  
pp. 1029-1037 ◽  
Author(s):  
ALAN HUGHES ◽  
SHANNON SASZIK ◽  
JOSEPH BILOTTA ◽  
PAUL J. DEMARCO ◽  
WARREN F. PATTERSON
Keyword(s):  
Spectral Sensitivity ◽  
Danio Rerio ◽  
Sensitivity Function ◽  
Chromatic Adaptation ◽  
Wave Component ◽  
Background Condition ◽  
Fundamental Properties ◽  
Increment Threshold ◽  
Cone Photopigments ◽  
Spectral Sensitivity Function

Microspectrophotometry studies show that zebrafish (Danio rerio) possess four cone photopigments. The purpose of this study was to determine the cone contributions to the zebrafish photopic increment threshold spectral-sensitivity function. Electroretinogram (ERG) b-wave responses to monochromatic lights presented on a broadband or chromatic background were obtained. It was found that under the broadband background condition, the zebrafish spectral-sensitivity function showed several peaks that were narrower in sensitivity compared to the cone spectra. The spectral-sensitivity function was modeled with L − M and M − S opponent interactions and nonopponent S- and U-cone mechanisms. Using chromatic adaptation designed to suppress the contribution of the S-cones, a strong U-cone contribution to the spectral-sensitivity function was revealed, and the contributions of the S-cones to the M − S mechanism were reduced. These results show that the b-wave component of the ERG receives input from all four cone types and appears to reflect color opponent mechanisms. Thus, zebrafish may possess the fundamental properties necessary for color vision.

Diurnal control of rod function in the chicken

1991 ◽  
Vol 6 (6) ◽  
pp. 641-653 ◽  
Author(s):  
Frank Schaeffel ◽  
Baerbel Rohrer ◽  
Eberhart Zrenner ◽  
Thomas Lemmer
Keyword(s):  
Spectral Sensitivity ◽  
Dark Adaptation ◽  
Wave Amplitude ◽  
Light And Electron Microscopy ◽  
Sensitivity Function ◽  
Two Phase ◽  
Flickering Light ◽  
Amplitude Criterion ◽  
Rod Function ◽  
Spectral Sensitivity Function

AbstractWe studied rod function in the chicken by recording corneal electroretinograms (ERGs). The following experiments were performed to demonstrate rod function during daytime: (1) determining the dark-adaptation function; (2) measuring the spectral sensitivity by a a–b-wave amplitude criterion in response to monochromatic flickering light of different frequencies ranging from 6.5–40.8 Hz (duty cycle 1: I); (3) analyzing the response vs. log stimulus intensity (V–log I) function in order to reveal a possible two phase process; and (4) determining the spectral sensitivity function either in a non-dark adapted state or after dark adaptation of the animals for I and 24 h. None of these experiments demonstrated clear evidence of rod function during daytime. On the other hand, we found rods histologically by light- and electron microscopy. Therefore, we repeated our ERG recordings during the night (between midnight and 3:00 A.M.). Without previous dark adaptation, rod function could be seen immediately in the same experiments described above. The result shows that, in the chicken, rods are turned on endogenously during the night but are scarcely functional during the day.

Ultraviolet colour opponency in the turtle retina

2001 ◽  
Vol 204 (14) ◽  
pp. 2527-2534 ◽  
Author(s):  
D. F. Ventura ◽  
Y. Zana ◽  
J. M. de Souza ◽  
R. D. DeVoe
Keyword(s):  
Receptive Field ◽  
Spectral Sensitivity ◽  
Ganglion Cells ◽  
Horizontal Cell ◽  
Amacrine Cells ◽  
Sensitivity Function ◽  
Neural Basis ◽  
Inner Retina ◽  
Cell Responses ◽  
Spectral Sensitivity Function

SUMMARY We have examined the functional architecture of the turtle Pseudemys scripta elegans retina with respect to colour processing, extending spectral stimulation into the ultraviolet, which has not been studied previously in the inner retina. We addressed two questions. (i) Is it possible to deduce the ultraviolet cone spectral sensitivity function through horizontal cell responses? (ii) Is there evidence for tetrachromatic neural mechanisms, i.e. UV/S response opponency? Using a constant response methodology we have isolated the ultraviolet cone input into the S/LM horizontal cell type and described it in fine detail. Monophasic (luminosity), biphasic L/M (red-green) and triphasic S/LM (yellow-blue) horizontal cells responded strongly to ultraviolet light. The blue-adapted spectral sensitivity function of a S/LM cell peaked in the ultraviolet and could be fitted to a porphyropsin cone template with a peak at 372nm. In the inner retina eight different combinations of spectral opponency were found in the centre of the receptive field of ganglion cells. Among amacrine cells the only types found were UVSM−L+ and its reverse. One amacrine and four ganglion cells were also opponent in the receptive field surround. UV/S opponency, seen in three different types of ganglion cell, provides a neural basis for discrimination of ultraviolet colours. In conclusion, the results strongly suggest that there is an ultraviolet channel and a neural basis for tetrachromacy in the turtle retina.

Spectral sensitivity of monocularly deprived cats

1992 ◽  
Vol 9 (6) ◽  
pp. 617-622 ◽  
Author(s):  
Zijiang J. He ◽  
Michael S. Loop
Keyword(s):  
Spectral Sensitivity ◽  
Sensitivity Function ◽  
Monocular Deprivation ◽  
Stimulus Light ◽  
Large White ◽  
Sensitivity Functions ◽  
Increment Threshold ◽  
Normal Transition ◽  
Intensity Functions ◽  
Spectral Sensitivity Function

AbstractThe reports of rod-dominated psychophysical spectral sensitivity from the deprived eye of monocularly lid-sutured (MD) monkeys are intriguing but difficult to reconcile with the absence of any reported deprivation effects in retina. As most studies of MD retina have been from cat, we have examined psychophysically the increment threshold spectral sensitivity of MD cats using both reaction time and simultaneous two-choice behavioral procedures. Although the deprived eyes exhibited an absolute increment threshold sensitivity deficit, both rod and cone spectral sensitivity functions were obtained on large white backgrounds. This normal transition from rod to cone vision, as background luminance increased, was also found in threshold vs. intensity functions. Using their deprived eye, some cats exhibited a rod spectral sensitivity function when a smaller, normally photopic, background was used providing some support for a hypothesis that the rod-dominated spectral sensitivity observed in monkey may represent detection of scattered stimulus light. Alternatively monocular deprivation may reveal a rod-dominated mechanism which exists in monkey but not in cat.

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