Abstract

The maximum area of complete spatial summation (i.e., Ricco’s area) for human short-wavelength-sensitive- (S-) and long-wavelength-sensitive- (L-) cone mechanisms was measured psychophysically at the fovea and at 1.5°, 4°, 8°, and 20° along the vertical meridian in the superior retina. Increment thresholds were measured for three observers by a temporal two-alternative forced-choice procedure. Test stimuli ranging from -0.36 to 4.61 log area (min2) were presented on concentric 12.3° adapting and auxiliary fields, which isolated either an S- or an L-cone mechanism on the plateau of its respective threshold versus intensity function. Test flash durations were 50 and 10 ms for the S- and L-cone mechanisms, respectively. The data indicate that, from 0° to 20°, Ricco’s area increases monotonically for the L-cone mechanism, is variable for the S-cone mechanism, and is larger for the S-cone mechanism than for the L-cone mechanism for essentially all retinal locations. This pattern of results most likely reflects differences in ganglion cell density and changes in neural convergence with retinal eccentricity.

© 2000 Optical Society of America

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  3. I. Lie, “Visual detection and resolution as a function of retina locus,” Vision Res. 20, 967–974 (1980).
    [CrossRef]
  4. L. Spillmann, A. Ransom-Hogg, R. Oehler, “A comparison of perceptive and receptive fields in man and monkey,” Human Neurobiol. 6, 51–62 (1987).
  5. B. Fischer, “Overlap of receptive field centers and representation of the visual field in the cat’s optic tract,” Vision Res. 13, 2113–2120 (1973).
    [CrossRef] [PubMed]
  6. B. E. Schefrin, M. L. Bieber, R. McLean, J. S. Werner, “The area of complete scotopic spatial summation enlarges with age,” J. Opt. Soc. Am. A 15, 340–348 (1998).
    [CrossRef]
  7. K. D. DaVila, W. S. Geisler, “The relative contributions of pre-neural and neural factors to areal summation in the fovea,” Vision Res. 31, 1369–1380 (1991).
    [CrossRef] [PubMed]
  8. G. Wald, “Area and visual threshold,” J. Gen. Physiol. 21, 269–287 (1938).
    [CrossRef] [PubMed]
  9. C. H. Graham, R. H. Brown, F. A. Mote, “The relation of size of stimulus and intensity in the human eye. I. Intensity thresholds for white light,” J. Exp. Psychol. 24, 555–573 (1939).
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    [CrossRef] [PubMed]
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    [CrossRef] [PubMed]
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    [CrossRef] [PubMed]
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  27. S. A. Hagstrom, J. Neitz, M. Neitz, “Variations in cone populations for red–green color vision examined by analysis of mRNA,” NeuroReport 9, 1963–1967 (1998).
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    [CrossRef] [PubMed]
  29. The term B/Y bistratified ganglion cell is used throughout the paper because it is convenient in anatomy. This nomenclature does not imply that these ganglion cells are responsible for the perception of blue and yellow hues.
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    [CrossRef] [PubMed]
  31. D. M. Dacey, “Physiology, morphology and spatial densities of identified ganglion cells types in primate retina,” in Higher-Order Processing in the Visual System, G. R. Bock, J. A. Goode, eds. (Wiley, New York, 1994), pp. 12–34.
  32. D. J. Calkins, Y. Tsukamoto, P. Sterling, “Microcircuitry and mosaic of a blue–yellow ganglion cell in the primate retina,” J. Neurosci. 18, 3373–3385 (1998).
    [PubMed]
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    [CrossRef] [PubMed]
  34. C. A. Curcio, K. A. Allen, “Topography of ganglion cells in human retina,” J. Comp. Neurol. 300, 5–25 (1990).
    [CrossRef] [PubMed]
  35. D. J. Calkins, P. Sterling, “Evidence that circuits for spatial and color vision segregate at the first retinal synapse,” Neuron 24, 313–321 (1999).
    [CrossRef] [PubMed]
  36. M. L. Bieber, B. E. Schefrin, J. S. Werner, “The senescence of cone photoreceptor sensitivity at 0°, 4°, and 8° retinal eccentricity and the possible relation to macular pigment density,” Invest. Ophthalmol. Visual Sci. Suppl. 39, S163 (1998).
  37. P. DeMarco, J. Pokorny, V. C. Smith, “Full-spectrum cone sensitivity functions for X-chromosome-linked anomalous trichromats,” J. Opt. Soc. Am. A 9, 1465–1476 (1992).
    [CrossRef] [PubMed]
  38. T.v.i. functions were also measured at 4°, 8°, and 20° retinal eccentricities. The peripheral functions confirmed that the thresholds measured at the selected background intensity were on the plateau of the t.v.i. function. Test sensitivity functions were also measured at 20° retinal eccentricity under conditions that isolated the S-cone and L-cone mechanisms. As in the fovea, the 20° test sensitivity functions verified the isolation of S- and L-cone mechanisms.
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    [CrossRef] [PubMed]
  40. H. Levitt, “Transformed up–down methods in psychoacoustics,” J. Acoust. Soc. Am. 49, 467–477 (1970).
    [CrossRef]
  41. F. M. de Monasterio, E. P. McCrane, J. K. Newlander, S. J. Schein, “Density profile of blue-sensitive cones along the horizontal meridian of macaque retina,” Invest. Ophthalmol. 26, 289–302 (1985).
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    [CrossRef] [PubMed]
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    [CrossRef] [PubMed]
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    [CrossRef] [PubMed]
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    [CrossRef]
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    [PubMed]
  47. R. W. Gubisch, “Optical performance of the human eye,” J. Opt. Soc. Am. 57, 407–415 (1967).
    [CrossRef]
  48. F. W. Campbell, R. W. Gubisch, “Optical quality of the human eye,” J. Physiol. (London) 186, 558–578 (1966).
  49. J. A. M. Jennings, W. N. Charman, “Optical image quality in the peripheral retina,” Am. J. Optom. Physiol. Opt. 55, 582–590 (1978).
    [CrossRef] [PubMed]
  50. R. Navarro, P. Artal, D. R. Williams, “Modulation transfer of the human eye as a function of retinal eccentricity,” J. Opt. Soc. Am. A 10, 201–212 (1993).
    [CrossRef] [PubMed]
  51. Ahnelt and colleagues (Ref. 21) did not provide an estimate of cone density at 4° and 8° retinal eccentricities. The 10° estimate for S and L cones has been included to show that the density of cones does not change from 10° to 20° retinal eccentricity. Although Curcio et al.23 did not extend their S-cone measurements beyond 8°, in an earlier paper Curcio et al.22 showed that total cone density remained relatively constant from 8° and beyond. Based on this finding, the 20° values were assumed to be the same as the density values at 8° retinal eccentricity. The mean cone density values across retinal quadrants from Curcio et al.22,23 were used in Fig. 6. Ahnelt et al.21 investigated only the temporal quadrant. The numbers of L cones from both studies were derived with the assumption of an L:M cone ratio of 2:1.24,25 If other estimates (e.g., Refs. 26–28) of the L:M cone ratio had been used, the L-cone density function would have shifted only along the y axis. This scalar shift would not affect the analyses presented in Fig. 6 and Table 1.
  52. B. B. Lee, “Receptive field structure in the primate retina,” Vision Res. 36, 631–644 (1996).
    [CrossRef] [PubMed]
  53. Retinal eccentricity values were obtained for ganglion cell density values within 8° of the fovea by use of the correction factor for ganglion cell displacement.54 The ganglion cell density values represent mean values across retinal quadrants. The 0° and 1.5° midget ganglion cell density values were derived from L-cone density values with the assumption of a 2:1 L:M cone ratio. If a different L:M ratio were used, the conclusions drawn from Fig. 7 would not change.
  54. D. M. Dacey, “Morphology of a small-field bistratified ganglion cells type in the macaque and human retina,” Visual Neurosci. 10, 1081–1098 (1993).
    [CrossRef]
  55. B. A. Wandell, E. N. Pugh, “A field-additive pathway detects brief-duration, long-wavelength incremental flashes,” Vision Res. 20, 613–624 (1980).
    [CrossRef] [PubMed]
  56. P. E. King-Smith, D. Carden, “Luminance and opponent-color contributions to visual detection and adaptation and to temporal and spatial integration,” J. Opt. Soc. Am. 66, 709–717 (1976).
    [CrossRef] [PubMed]
  57. B. A. Wandell, E. N. Pugh, “Detection of long-duration, long wavelength incremental flashes by a chromatically coded pathway,” Vision Res. 20, 625–636 (1980).
    [CrossRef]
  58. D. M. Dacey, M. R. Petersen, “Dendritic field size and morphology of midget and parasol ganglion cells of the human retina,” Proc. Natl. Acad. Sci. USA 89, 9666–9670 (1992).
    [CrossRef] [PubMed]

1999 (2)

A. Roorda, D. R. Williams, “The arrangement of the three cone classes in the living human eye,” Nature 397, 520–522 (1999).
[CrossRef] [PubMed]

D. J. Calkins, P. Sterling, “Evidence that circuits for spatial and color vision segregate at the first retinal synapse,” Neuron 24, 313–321 (1999).
[CrossRef] [PubMed]

1998 (4)

M. L. Bieber, B. E. Schefrin, J. S. Werner, “The senescence of cone photoreceptor sensitivity at 0°, 4°, and 8° retinal eccentricity and the possible relation to macular pigment density,” Invest. Ophthalmol. Visual Sci. Suppl. 39, S163 (1998).

D. J. Calkins, Y. Tsukamoto, P. Sterling, “Microcircuitry and mosaic of a blue–yellow ganglion cell in the primate retina,” J. Neurosci. 18, 3373–3385 (1998).
[PubMed]

S. A. Hagstrom, J. Neitz, M. Neitz, “Variations in cone populations for red–green color vision examined by analysis of mRNA,” NeuroReport 9, 1963–1967 (1998).
[CrossRef] [PubMed]

B. E. Schefrin, M. L. Bieber, R. McLean, J. S. Werner, “The area of complete scotopic spatial summation enlarges with age,” J. Opt. Soc. Am. A 15, 340–348 (1998).
[CrossRef]

1996 (1)

B. B. Lee, “Receptive field structure in the primate retina,” Vision Res. 36, 631–644 (1996).
[CrossRef] [PubMed]

1994 (1)

D. M. Dacey, B. B. Lee, “The ‘blue-on’ opponent pathway in primate retina originates from a distinct bistratified ganglion cell type,” Nature 367, 731–735 (1994).
[CrossRef] [PubMed]

1993 (2)

D. M. Dacey, “Morphology of a small-field bistratified ganglion cells type in the macaque and human retina,” Visual Neurosci. 10, 1081–1098 (1993).
[CrossRef]

R. Navarro, P. Artal, D. R. Williams, “Modulation transfer of the human eye as a function of retinal eccentricity,” J. Opt. Soc. Am. A 10, 201–212 (1993).
[CrossRef] [PubMed]

1992 (3)

D. M. Dacey, M. R. Petersen, “Dendritic field size and morphology of midget and parasol ganglion cells of the human retina,” Proc. Natl. Acad. Sci. USA 89, 9666–9670 (1992).
[CrossRef] [PubMed]

P. DeMarco, J. Pokorny, V. C. Smith, “Full-spectrum cone sensitivity functions for X-chromosome-linked anomalous trichromats,” J. Opt. Soc. Am. A 9, 1465–1476 (1992).
[CrossRef] [PubMed]

J. L. Nerger, C. M. Cicerone, “The ratio of L cones to M cones in the human parafoveal retina,” Vision Res. 32, 879–888 (1992).
[CrossRef] [PubMed]

1991 (2)

C. A. Curcio, K. A. Allen, K. R. Sloan, C. L. Lerea, J. B. Hurley, I. B. Klock, A. H. Milam, “Distribution and morphology of human cone photoreceptors stained with anti-blue opsin,” J. Comp. Neurol. 312, 610–624 (1991).
[CrossRef] [PubMed]

K. D. DaVila, W. S. Geisler, “The relative contributions of pre-neural and neural factors to areal summation in the fovea,” Vision Res. 31, 1369–1380 (1991).
[CrossRef] [PubMed]

1990 (2)

C. A. Curcio, K. A. Allen, “Topography of ganglion cells in human retina,” J. Comp. Neurol. 300, 5–25 (1990).
[CrossRef] [PubMed]

C. A. Curcio, K. R. Sloan, R. E. Kalina, A. E. Hendrickson, “Human photoreceptor topography,” J. Comp. Neurol. 292, 497–523 (1990).
[CrossRef] [PubMed]

1989 (3)

H. Wässle, U. Grünert, J. Röhrenbeck, B. B. Boycott, “Cortical magnification factor and the ganglion cell density of the primate retina,” Nature 341, 643–646 (1989).
[CrossRef] [PubMed]

C. M. Cicerone, J. L. Nerger, “The relative numbers of long-wavelength-sensitive to middle-wavelength-sensitive cones in the human fovea centralis,” Vision Res. 29, 115–128 (1989).
[CrossRef] [PubMed]

R. L. P. Vimal, J. Pokorny, V. C. Smith, S. K. Shevell, “Foveal cone thresholds,” Vision Res. 29, 61–78 (1989).
[CrossRef] [PubMed]

1987 (2)

P. K. Ahnelt, H. Kolb, R. Pflug, “Identification of a subtype of cone photoreceptor, likely to be blue sensitive, in the human retina,” J. Comp. Neurol. 255, 18–34 (1987).
[CrossRef] [PubMed]

L. Spillmann, A. Ransom-Hogg, R. Oehler, “A comparison of perceptive and receptive fields in man and monkey,” Human Neurobiol. 6, 51–62 (1987).

1986 (2)

M. A. Johnson, “Color vision in the peripheral retina,” Am. J. Optom. Physiol. Opt. 63, 97–103 (1986).
[CrossRef] [PubMed]

P. A. Howarth, A. Bradley, “The longitudinal chromatic aberration of the human eye, and its correction,” Vision Res. 26, 361–366 (1986).
[CrossRef] [PubMed]

1985 (1)

F. M. de Monasterio, E. P. McCrane, J. K. Newlander, S. J. Schein, “Density profile of blue-sensitive cones along the horizontal meridian of macaque retina,” Invest. Ophthalmol. 26, 289–302 (1985).

1981 (3)

1980 (3)

I. Lie, “Visual detection and resolution as a function of retina locus,” Vision Res. 20, 967–974 (1980).
[CrossRef]

B. A. Wandell, E. N. Pugh, “Detection of long-duration, long wavelength incremental flashes by a chromatically coded pathway,” Vision Res. 20, 625–636 (1980).
[CrossRef]

B. A. Wandell, E. N. Pugh, “A field-additive pathway detects brief-duration, long-wavelength incremental flashes,” Vision Res. 20, 613–624 (1980).
[CrossRef] [PubMed]

1978 (1)

J. A. M. Jennings, W. N. Charman, “Optical image quality in the peripheral retina,” Am. J. Optom. Physiol. Opt. 55, 582–590 (1978).
[CrossRef] [PubMed]

1977 (1)

A. M. W. Scholtes, M. A. Bouman, “Psychophysical experiments on spatial summation at threshold level of the human peripheral retina,” Vision Res. 17, 867–873 (1977).
[CrossRef] [PubMed]

1976 (2)

W. N. Charman, J. A. M. Jennings, “The optical quality of the monochromatic retinal image as a function of focus,” Br. J. Physiol. Opt. 31, 119–134 (1976).
[PubMed]

P. E. King-Smith, D. Carden, “Luminance and opponent-color contributions to visual detection and adaptation and to temporal and spatial integration,” J. Opt. Soc. Am. 66, 709–717 (1976).
[CrossRef] [PubMed]

1973 (1)

B. Fischer, “Overlap of receptive field centers and representation of the visual field in the cat’s optic tract,” Vision Res. 13, 2113–2120 (1973).
[CrossRef] [PubMed]

1971 (2)

F. Dannheim, S. M. Drance, “Studies of spatial summation of central retinal areas in normal people of all ages,” Can. J. Ophthalmol. 6, 311–319 (1971).
[PubMed]

B. Sakitt, “Configuration dependence of scotopic spatial summation,” J. Physiol. (London) 216, 513–529 (1971).

1970 (2)

H. Levitt, “Transformed up–down methods in psychoacoustics,” J. Acoust. Soc. Am. 49, 467–477 (1970).
[CrossRef]

M. E. Wilson, “Invariant features of spatial summation with changing locus in the visual field,” J. Physiol. (London) 207, 611–622 (1970).

1967 (1)

1966 (2)

F. W. Campbell, R. W. Gubisch, “Optical quality of the human eye,” J. Physiol. (London) 186, 558–578 (1966).

G. Westheimer, “The Maxwellian view,” Vision Res. 6, 669–682 (1966).
[CrossRef] [PubMed]

1965 (1)

V. D. Glezer, “The receptive fields of the retina,” Vision Res. 5, 497–525 (1965).
[CrossRef] [PubMed]

1964 (1)

1962 (1)

P. E. Hallett, F. H. C. Marriott, F. C. Rodger, “The relationship of visual threshold to retinal position and area,” J. Physiol. (London) 160, 364–373 (1962).

1961 (1)

1958 (1)

H. B. Barlow, “Temporal and spatial summation in human vision at different background intensities,” J. Physiol. (London) 141, 337–350 (1958).

1957 (1)

1954 (1)

G. S. Brindley, “The summation areas of human colour-receptive mechanisms at increment threshold,” J. Physiol. (London) 124, 400–408 (1954).

1939 (1)

C. H. Graham, R. H. Brown, F. A. Mote, “The relation of size of stimulus and intensity in the human eye. I. Intensity thresholds for white light,” J. Exp. Psychol. 24, 555–573 (1939).
[CrossRef]

1938 (1)

G. Wald, “Area and visual threshold,” J. Gen. Physiol. 21, 269–287 (1938).
[CrossRef] [PubMed]

1877 (1)

A. Ricco, “Relazione fra il minimo angolo visuale l’intensita luminosa,” Mem. R. Accad. Sci. Lett. Arti Modena 17, 47–160 (1877).

Ahnelt, P. K.

P. K. Ahnelt, H. Kolb, R. Pflug, “Identification of a subtype of cone photoreceptor, likely to be blue sensitive, in the human retina,” J. Comp. Neurol. 255, 18–34 (1987).
[CrossRef] [PubMed]

Allen, K. A.

C. A. Curcio, K. A. Allen, K. R. Sloan, C. L. Lerea, J. B. Hurley, I. B. Klock, A. H. Milam, “Distribution and morphology of human cone photoreceptors stained with anti-blue opsin,” J. Comp. Neurol. 312, 610–624 (1991).
[CrossRef] [PubMed]

C. A. Curcio, K. A. Allen, “Topography of ganglion cells in human retina,” J. Comp. Neurol. 300, 5–25 (1990).
[CrossRef] [PubMed]

Artal, P.

Barlow, H. B.

H. B. Barlow, “Temporal and spatial summation in human vision at different background intensities,” J. Physiol. (London) 141, 337–350 (1958).

Baumgardt, E.

Bedford, R. E.

Bieber, M. L.

M. L. Bieber, B. E. Schefrin, J. S. Werner, “The senescence of cone photoreceptor sensitivity at 0°, 4°, and 8° retinal eccentricity and the possible relation to macular pigment density,” Invest. Ophthalmol. Visual Sci. Suppl. 39, S163 (1998).

B. E. Schefrin, M. L. Bieber, R. McLean, J. S. Werner, “The area of complete scotopic spatial summation enlarges with age,” J. Opt. Soc. Am. A 15, 340–348 (1998).
[CrossRef]

Bouman, M. A.

A. M. W. Scholtes, M. A. Bouman, “Psychophysical experiments on spatial summation at threshold level of the human peripheral retina,” Vision Res. 17, 867–873 (1977).
[CrossRef] [PubMed]

Boycott, B. B.

H. Wässle, U. Grünert, J. Röhrenbeck, B. B. Boycott, “Cortical magnification factor and the ganglion cell density of the primate retina,” Nature 341, 643–646 (1989).
[CrossRef] [PubMed]

Bradley, A.

P. A. Howarth, A. Bradley, “The longitudinal chromatic aberration of the human eye, and its correction,” Vision Res. 26, 361–366 (1986).
[CrossRef] [PubMed]

Brindley, G. S.

G. S. Brindley, “The summation areas of human colour-receptive mechanisms at increment threshold,” J. Physiol. (London) 124, 400–408 (1954).

Brown, R. H.

C. H. Graham, R. H. Brown, F. A. Mote, “The relation of size of stimulus and intensity in the human eye. I. Intensity thresholds for white light,” J. Exp. Psychol. 24, 555–573 (1939).
[CrossRef]

Calkins, D. J.

D. J. Calkins, P. Sterling, “Evidence that circuits for spatial and color vision segregate at the first retinal synapse,” Neuron 24, 313–321 (1999).
[CrossRef] [PubMed]

D. J. Calkins, Y. Tsukamoto, P. Sterling, “Microcircuitry and mosaic of a blue–yellow ganglion cell in the primate retina,” J. Neurosci. 18, 3373–3385 (1998).
[PubMed]

Campbell, F. W.

F. W. Campbell, R. W. Gubisch, “Optical quality of the human eye,” J. Physiol. (London) 186, 558–578 (1966).

Carden, D.

Charman, W. N.

J. A. M. Jennings, W. N. Charman, “Optical image quality in the peripheral retina,” Am. J. Optom. Physiol. Opt. 55, 582–590 (1978).
[CrossRef] [PubMed]

W. N. Charman, J. A. M. Jennings, “The optical quality of the monochromatic retinal image as a function of focus,” Br. J. Physiol. Opt. 31, 119–134 (1976).
[PubMed]

Cicerone, C. M.

J. L. Nerger, C. M. Cicerone, “The ratio of L cones to M cones in the human parafoveal retina,” Vision Res. 32, 879–888 (1992).
[CrossRef] [PubMed]

C. M. Cicerone, J. L. Nerger, “The relative numbers of long-wavelength-sensitive to middle-wavelength-sensitive cones in the human fovea centralis,” Vision Res. 29, 115–128 (1989).
[CrossRef] [PubMed]

Curcio, C. A.

C. A. Curcio, K. A. Allen, K. R. Sloan, C. L. Lerea, J. B. Hurley, I. B. Klock, A. H. Milam, “Distribution and morphology of human cone photoreceptors stained with anti-blue opsin,” J. Comp. Neurol. 312, 610–624 (1991).
[CrossRef] [PubMed]

C. A. Curcio, K. R. Sloan, R. E. Kalina, A. E. Hendrickson, “Human photoreceptor topography,” J. Comp. Neurol. 292, 497–523 (1990).
[CrossRef] [PubMed]

C. A. Curcio, K. A. Allen, “Topography of ganglion cells in human retina,” J. Comp. Neurol. 300, 5–25 (1990).
[CrossRef] [PubMed]

Dacey, D. M.

D. M. Dacey, B. B. Lee, “The ‘blue-on’ opponent pathway in primate retina originates from a distinct bistratified ganglion cell type,” Nature 367, 731–735 (1994).
[CrossRef] [PubMed]

D. M. Dacey, “Morphology of a small-field bistratified ganglion cells type in the macaque and human retina,” Visual Neurosci. 10, 1081–1098 (1993).
[CrossRef]

D. M. Dacey, M. R. Petersen, “Dendritic field size and morphology of midget and parasol ganglion cells of the human retina,” Proc. Natl. Acad. Sci. USA 89, 9666–9670 (1992).
[CrossRef] [PubMed]

D. M. Dacey, “Physiology, morphology and spatial densities of identified ganglion cells types in primate retina,” in Higher-Order Processing in the Visual System, G. R. Bock, J. A. Goode, eds. (Wiley, New York, 1994), pp. 12–34.

Dannheim, F.

F. Dannheim, S. M. Drance, “Studies of spatial summation of central retinal areas in normal people of all ages,” Can. J. Ophthalmol. 6, 311–319 (1971).
[PubMed]

DaVila, K. D.

K. D. DaVila, W. S. Geisler, “The relative contributions of pre-neural and neural factors to areal summation in the fovea,” Vision Res. 31, 1369–1380 (1991).
[CrossRef] [PubMed]

de Monasterio, F. M.

F. M. de Monasterio, E. P. McCrane, J. K. Newlander, S. J. Schein, “Density profile of blue-sensitive cones along the horizontal meridian of macaque retina,” Invest. Ophthalmol. 26, 289–302 (1985).

DeMarco, P.

Drance, S. M.

F. Dannheim, S. M. Drance, “Studies of spatial summation of central retinal areas in normal people of all ages,” Can. J. Ophthalmol. 6, 311–319 (1971).
[PubMed]

Fischer, B.

B. Fischer, “Overlap of receptive field centers and representation of the visual field in the cat’s optic tract,” Vision Res. 13, 2113–2120 (1973).
[CrossRef] [PubMed]

Geisler, W. S.

K. D. DaVila, W. S. Geisler, “The relative contributions of pre-neural and neural factors to areal summation in the fovea,” Vision Res. 31, 1369–1380 (1991).
[CrossRef] [PubMed]

Glezer, V. D.

V. D. Glezer, “The receptive fields of the retina,” Vision Res. 5, 497–525 (1965).
[CrossRef] [PubMed]

Graham, C. H.

C. H. Graham, R. H. Brown, F. A. Mote, “The relation of size of stimulus and intensity in the human eye. I. Intensity thresholds for white light,” J. Exp. Psychol. 24, 555–573 (1939).
[CrossRef]

Grünert, U.

H. Wässle, U. Grünert, J. Röhrenbeck, B. B. Boycott, “Cortical magnification factor and the ganglion cell density of the primate retina,” Nature 341, 643–646 (1989).
[CrossRef] [PubMed]

Gubisch, R. W.

R. W. Gubisch, “Optical performance of the human eye,” J. Opt. Soc. Am. 57, 407–415 (1967).
[CrossRef]

F. W. Campbell, R. W. Gubisch, “Optical quality of the human eye,” J. Physiol. (London) 186, 558–578 (1966).

Hagstrom, S. A.

S. A. Hagstrom, J. Neitz, M. Neitz, “Variations in cone populations for red–green color vision examined by analysis of mRNA,” NeuroReport 9, 1963–1967 (1998).
[CrossRef] [PubMed]

Hallett, P. E.

P. E. Hallett, F. H. C. Marriott, F. C. Rodger, “The relationship of visual threshold to retinal position and area,” J. Physiol. (London) 160, 364–373 (1962).

Hayhoe, M. M.

D. R. Williams, D. I. A. MacLeod, M. M. Hayhoe, “Punctate sensitivity of the blue-sensitive mechanism,” Vision Res. 21, 1357–1375 (1981).
[CrossRef] [PubMed]

Hendrickson, A. E.

C. A. Curcio, K. R. Sloan, R. E. Kalina, A. E. Hendrickson, “Human photoreceptor topography,” J. Comp. Neurol. 292, 497–523 (1990).
[CrossRef] [PubMed]

Hillmann, B.

Howarth, P. A.

P. A. Howarth, A. Bradley, “The longitudinal chromatic aberration of the human eye, and its correction,” Vision Res. 26, 361–366 (1986).
[CrossRef] [PubMed]

Hurley, J. B.

C. A. Curcio, K. A. Allen, K. R. Sloan, C. L. Lerea, J. B. Hurley, I. B. Klock, A. H. Milam, “Distribution and morphology of human cone photoreceptors stained with anti-blue opsin,” J. Comp. Neurol. 312, 610–624 (1991).
[CrossRef] [PubMed]

Inui, T.

Jennings, J. A. M.

J. A. M. Jennings, W. N. Charman, “Optical image quality in the peripheral retina,” Am. J. Optom. Physiol. Opt. 55, 582–590 (1978).
[CrossRef] [PubMed]

W. N. Charman, J. A. M. Jennings, “The optical quality of the monochromatic retinal image as a function of focus,” Br. J. Physiol. Opt. 31, 119–134 (1976).
[PubMed]

Johnson, M. A.

M. A. Johnson, “Color vision in the peripheral retina,” Am. J. Optom. Physiol. Opt. 63, 97–103 (1986).
[CrossRef] [PubMed]

Kalina, R. E.

C. A. Curcio, K. R. Sloan, R. E. Kalina, A. E. Hendrickson, “Human photoreceptor topography,” J. Comp. Neurol. 292, 497–523 (1990).
[CrossRef] [PubMed]

Kani, K.

King-Smith, P. E.

Klock, I. B.

C. A. Curcio, K. A. Allen, K. R. Sloan, C. L. Lerea, J. B. Hurley, I. B. Klock, A. H. Milam, “Distribution and morphology of human cone photoreceptors stained with anti-blue opsin,” J. Comp. Neurol. 312, 610–624 (1991).
[CrossRef] [PubMed]

Kolb, H.

P. K. Ahnelt, H. Kolb, R. Pflug, “Identification of a subtype of cone photoreceptor, likely to be blue sensitive, in the human retina,” J. Comp. Neurol. 255, 18–34 (1987).
[CrossRef] [PubMed]

Krauskopf, J.

Lee, B. B.

B. B. Lee, “Receptive field structure in the primate retina,” Vision Res. 36, 631–644 (1996).
[CrossRef] [PubMed]

D. M. Dacey, B. B. Lee, “The ‘blue-on’ opponent pathway in primate retina originates from a distinct bistratified ganglion cell type,” Nature 367, 731–735 (1994).
[CrossRef] [PubMed]

Lerea, C. L.

C. A. Curcio, K. A. Allen, K. R. Sloan, C. L. Lerea, J. B. Hurley, I. B. Klock, A. H. Milam, “Distribution and morphology of human cone photoreceptors stained with anti-blue opsin,” J. Comp. Neurol. 312, 610–624 (1991).
[CrossRef] [PubMed]

Levitt, H.

H. Levitt, “Transformed up–down methods in psychoacoustics,” J. Acoust. Soc. Am. 49, 467–477 (1970).
[CrossRef]

Lie, I.

I. Lie, “Visual detection and resolution as a function of retina locus,” Vision Res. 20, 967–974 (1980).
[CrossRef]

MacLeod, D. I. A.

D. R. Williams, D. I. A. MacLeod, M. M. Hayhoe, “Punctate sensitivity of the blue-sensitive mechanism,” Vision Res. 21, 1357–1375 (1981).
[CrossRef] [PubMed]

Marriott, F. H. C.

P. E. Hallett, F. H. C. Marriott, F. C. Rodger, “The relationship of visual threshold to retinal position and area,” J. Physiol. (London) 160, 364–373 (1962).

McCrane, E. P.

F. M. de Monasterio, E. P. McCrane, J. K. Newlander, S. J. Schein, “Density profile of blue-sensitive cones along the horizontal meridian of macaque retina,” Invest. Ophthalmol. 26, 289–302 (1985).

McLean, R.

Milam, A. H.

C. A. Curcio, K. A. Allen, K. R. Sloan, C. L. Lerea, J. B. Hurley, I. B. Klock, A. H. Milam, “Distribution and morphology of human cone photoreceptors stained with anti-blue opsin,” J. Comp. Neurol. 312, 610–624 (1991).
[CrossRef] [PubMed]

Mimura, O.

Mote, F. A.

C. H. Graham, R. H. Brown, F. A. Mote, “The relation of size of stimulus and intensity in the human eye. I. Intensity thresholds for white light,” J. Exp. Psychol. 24, 555–573 (1939).
[CrossRef]

Navarro, R.

Neitz, J.

S. A. Hagstrom, J. Neitz, M. Neitz, “Variations in cone populations for red–green color vision examined by analysis of mRNA,” NeuroReport 9, 1963–1967 (1998).
[CrossRef] [PubMed]

Neitz, M.

S. A. Hagstrom, J. Neitz, M. Neitz, “Variations in cone populations for red–green color vision examined by analysis of mRNA,” NeuroReport 9, 1963–1967 (1998).
[CrossRef] [PubMed]

Nerger, J. L.

J. L. Nerger, C. M. Cicerone, “The ratio of L cones to M cones in the human parafoveal retina,” Vision Res. 32, 879–888 (1992).
[CrossRef] [PubMed]

C. M. Cicerone, J. L. Nerger, “The relative numbers of long-wavelength-sensitive to middle-wavelength-sensitive cones in the human fovea centralis,” Vision Res. 29, 115–128 (1989).
[CrossRef] [PubMed]

Newlander, J. K.

F. M. de Monasterio, E. P. McCrane, J. K. Newlander, S. J. Schein, “Density profile of blue-sensitive cones along the horizontal meridian of macaque retina,” Invest. Ophthalmol. 26, 289–302 (1985).

Oehler, R.

L. Spillmann, A. Ransom-Hogg, R. Oehler, “A comparison of perceptive and receptive fields in man and monkey,” Human Neurobiol. 6, 51–62 (1987).

Petersen, M. R.

D. M. Dacey, M. R. Petersen, “Dendritic field size and morphology of midget and parasol ganglion cells of the human retina,” Proc. Natl. Acad. Sci. USA 89, 9666–9670 (1992).
[CrossRef] [PubMed]

Pflug, R.

P. K. Ahnelt, H. Kolb, R. Pflug, “Identification of a subtype of cone photoreceptor, likely to be blue sensitive, in the human retina,” J. Comp. Neurol. 255, 18–34 (1987).
[CrossRef] [PubMed]

Pokorny, J.

Powell, I.

Pugh, E. N.

B. A. Wandell, E. N. Pugh, “Detection of long-duration, long wavelength incremental flashes by a chromatically coded pathway,” Vision Res. 20, 625–636 (1980).
[CrossRef]

B. A. Wandell, E. N. Pugh, “A field-additive pathway detects brief-duration, long-wavelength incremental flashes,” Vision Res. 20, 613–624 (1980).
[CrossRef] [PubMed]

Ransom-Hogg, A.

L. Spillmann, A. Ransom-Hogg, R. Oehler, “A comparison of perceptive and receptive fields in man and monkey,” Human Neurobiol. 6, 51–62 (1987).

Ricco, A.

A. Ricco, “Relazione fra il minimo angolo visuale l’intensita luminosa,” Mem. R. Accad. Sci. Lett. Arti Modena 17, 47–160 (1877).

Rodger, F. C.

P. E. Hallett, F. H. C. Marriott, F. C. Rodger, “The relationship of visual threshold to retinal position and area,” J. Physiol. (London) 160, 364–373 (1962).

Röhrenbeck, J.

H. Wässle, U. Grünert, J. Röhrenbeck, B. B. Boycott, “Cortical magnification factor and the ganglion cell density of the primate retina,” Nature 341, 643–646 (1989).
[CrossRef] [PubMed]

Roorda, A.

A. Roorda, D. R. Williams, “The arrangement of the three cone classes in the living human eye,” Nature 397, 520–522 (1999).
[CrossRef] [PubMed]

Sakitt, B.

B. Sakitt, “Configuration dependence of scotopic spatial summation,” J. Physiol. (London) 216, 513–529 (1971).

Schefrin, B. E.

B. E. Schefrin, M. L. Bieber, R. McLean, J. S. Werner, “The area of complete scotopic spatial summation enlarges with age,” J. Opt. Soc. Am. A 15, 340–348 (1998).
[CrossRef]

M. L. Bieber, B. E. Schefrin, J. S. Werner, “The senescence of cone photoreceptor sensitivity at 0°, 4°, and 8° retinal eccentricity and the possible relation to macular pigment density,” Invest. Ophthalmol. Visual Sci. Suppl. 39, S163 (1998).

Schein, S. J.

F. M. de Monasterio, E. P. McCrane, J. K. Newlander, S. J. Schein, “Density profile of blue-sensitive cones along the horizontal meridian of macaque retina,” Invest. Ophthalmol. 26, 289–302 (1985).

Scholtes, A. M. W.

A. M. W. Scholtes, M. A. Bouman, “Psychophysical experiments on spatial summation at threshold level of the human peripheral retina,” Vision Res. 17, 867–873 (1977).
[CrossRef] [PubMed]

Shevell, S. K.

R. L. P. Vimal, J. Pokorny, V. C. Smith, S. K. Shevell, “Foveal cone thresholds,” Vision Res. 29, 61–78 (1989).
[CrossRef] [PubMed]

Sloan, K. R.

C. A. Curcio, K. A. Allen, K. R. Sloan, C. L. Lerea, J. B. Hurley, I. B. Klock, A. H. Milam, “Distribution and morphology of human cone photoreceptors stained with anti-blue opsin,” J. Comp. Neurol. 312, 610–624 (1991).
[CrossRef] [PubMed]

C. A. Curcio, K. R. Sloan, R. E. Kalina, A. E. Hendrickson, “Human photoreceptor topography,” J. Comp. Neurol. 292, 497–523 (1990).
[CrossRef] [PubMed]

Smith, V. C.

Spillmann, L.

L. Spillmann, A. Ransom-Hogg, R. Oehler, “A comparison of perceptive and receptive fields in man and monkey,” Human Neurobiol. 6, 51–62 (1987).

Sterling, P.

D. J. Calkins, P. Sterling, “Evidence that circuits for spatial and color vision segregate at the first retinal synapse,” Neuron 24, 313–321 (1999).
[CrossRef] [PubMed]

D. J. Calkins, Y. Tsukamoto, P. Sterling, “Microcircuitry and mosaic of a blue–yellow ganglion cell in the primate retina,” J. Neurosci. 18, 3373–3385 (1998).
[PubMed]

Tsukamoto, Y.

D. J. Calkins, Y. Tsukamoto, P. Sterling, “Microcircuitry and mosaic of a blue–yellow ganglion cell in the primate retina,” J. Neurosci. 18, 3373–3385 (1998).
[PubMed]

Vimal, R. L. P.

R. L. P. Vimal, J. Pokorny, V. C. Smith, S. K. Shevell, “Foveal cone thresholds,” Vision Res. 29, 61–78 (1989).
[CrossRef] [PubMed]

Wald, G.

G. Wald, “Area and visual threshold,” J. Gen. Physiol. 21, 269–287 (1938).
[CrossRef] [PubMed]

Wandell, B. A.

B. A. Wandell, E. N. Pugh, “A field-additive pathway detects brief-duration, long-wavelength incremental flashes,” Vision Res. 20, 613–624 (1980).
[CrossRef] [PubMed]

B. A. Wandell, E. N. Pugh, “Detection of long-duration, long wavelength incremental flashes by a chromatically coded pathway,” Vision Res. 20, 625–636 (1980).
[CrossRef]

Wässle, H.

H. Wässle, U. Grünert, J. Röhrenbeck, B. B. Boycott, “Cortical magnification factor and the ganglion cell density of the primate retina,” Nature 341, 643–646 (1989).
[CrossRef] [PubMed]

Werner, J. S.

B. E. Schefrin, M. L. Bieber, R. McLean, J. S. Werner, “The area of complete scotopic spatial summation enlarges with age,” J. Opt. Soc. Am. A 15, 340–348 (1998).
[CrossRef]

M. L. Bieber, B. E. Schefrin, J. S. Werner, “The senescence of cone photoreceptor sensitivity at 0°, 4°, and 8° retinal eccentricity and the possible relation to macular pigment density,” Invest. Ophthalmol. Visual Sci. Suppl. 39, S163 (1998).

Westheimer, G.

G. Westheimer, “The Maxwellian view,” Vision Res. 6, 669–682 (1966).
[CrossRef] [PubMed]

Williams, D. R.

A. Roorda, D. R. Williams, “The arrangement of the three cone classes in the living human eye,” Nature 397, 520–522 (1999).
[CrossRef] [PubMed]

R. Navarro, P. Artal, D. R. Williams, “Modulation transfer of the human eye as a function of retinal eccentricity,” J. Opt. Soc. Am. A 10, 201–212 (1993).
[CrossRef] [PubMed]

D. R. Williams, D. I. A. MacLeod, M. M. Hayhoe, “Punctate sensitivity of the blue-sensitive mechanism,” Vision Res. 21, 1357–1375 (1981).
[CrossRef] [PubMed]

Wilson, M. E.

M. E. Wilson, “Invariant features of spatial summation with changing locus in the visual field,” J. Physiol. (London) 207, 611–622 (1970).

Wyszecki, G.

Am. J. Optom. Physiol. Opt. (2)

M. A. Johnson, “Color vision in the peripheral retina,” Am. J. Optom. Physiol. Opt. 63, 97–103 (1986).
[CrossRef] [PubMed]

J. A. M. Jennings, W. N. Charman, “Optical image quality in the peripheral retina,” Am. J. Optom. Physiol. Opt. 55, 582–590 (1978).
[CrossRef] [PubMed]

Appl. Opt. (1)

Br. J. Physiol. Opt. (1)

W. N. Charman, J. A. M. Jennings, “The optical quality of the monochromatic retinal image as a function of focus,” Br. J. Physiol. Opt. 31, 119–134 (1976).
[PubMed]

Can. J. Ophthalmol. (1)

F. Dannheim, S. M. Drance, “Studies of spatial summation of central retinal areas in normal people of all ages,” Can. J. Ophthalmol. 6, 311–319 (1971).
[PubMed]

Human Neurobiol. (1)

L. Spillmann, A. Ransom-Hogg, R. Oehler, “A comparison of perceptive and receptive fields in man and monkey,” Human Neurobiol. 6, 51–62 (1987).

Invest. Ophthalmol. (1)

F. M. de Monasterio, E. P. McCrane, J. K. Newlander, S. J. Schein, “Density profile of blue-sensitive cones along the horizontal meridian of macaque retina,” Invest. Ophthalmol. 26, 289–302 (1985).

Invest. Ophthalmol. Visual Sci. Suppl. (1)

M. L. Bieber, B. E. Schefrin, J. S. Werner, “The senescence of cone photoreceptor sensitivity at 0°, 4°, and 8° retinal eccentricity and the possible relation to macular pigment density,” Invest. Ophthalmol. Visual Sci. Suppl. 39, S163 (1998).

J. Acoust. Soc. Am. (1)

H. Levitt, “Transformed up–down methods in psychoacoustics,” J. Acoust. Soc. Am. 49, 467–477 (1970).
[CrossRef]

J. Comp. Neurol. (4)

C. A. Curcio, K. A. Allen, “Topography of ganglion cells in human retina,” J. Comp. Neurol. 300, 5–25 (1990).
[CrossRef] [PubMed]

P. K. Ahnelt, H. Kolb, R. Pflug, “Identification of a subtype of cone photoreceptor, likely to be blue sensitive, in the human retina,” J. Comp. Neurol. 255, 18–34 (1987).
[CrossRef] [PubMed]

C. A. Curcio, K. R. Sloan, R. E. Kalina, A. E. Hendrickson, “Human photoreceptor topography,” J. Comp. Neurol. 292, 497–523 (1990).
[CrossRef] [PubMed]

C. A. Curcio, K. A. Allen, K. R. Sloan, C. L. Lerea, J. B. Hurley, I. B. Klock, A. H. Milam, “Distribution and morphology of human cone photoreceptors stained with anti-blue opsin,” J. Comp. Neurol. 312, 610–624 (1991).
[CrossRef] [PubMed]

J. Exp. Psychol. (1)

C. H. Graham, R. H. Brown, F. A. Mote, “The relation of size of stimulus and intensity in the human eye. I. Intensity thresholds for white light,” J. Exp. Psychol. 24, 555–573 (1939).
[CrossRef]

J. Gen. Physiol. (1)

G. Wald, “Area and visual threshold,” J. Gen. Physiol. 21, 269–287 (1938).
[CrossRef] [PubMed]

J. Neurosci. (1)

D. J. Calkins, Y. Tsukamoto, P. Sterling, “Microcircuitry and mosaic of a blue–yellow ganglion cell in the primate retina,” J. Neurosci. 18, 3373–3385 (1998).
[PubMed]

J. Opt. Soc. Am. (6)

J. Opt. Soc. Am. A (3)

J. Physiol. (London) (6)

F. W. Campbell, R. W. Gubisch, “Optical quality of the human eye,” J. Physiol. (London) 186, 558–578 (1966).

B. Sakitt, “Configuration dependence of scotopic spatial summation,” J. Physiol. (London) 216, 513–529 (1971).

G. S. Brindley, “The summation areas of human colour-receptive mechanisms at increment threshold,” J. Physiol. (London) 124, 400–408 (1954).

H. B. Barlow, “Temporal and spatial summation in human vision at different background intensities,” J. Physiol. (London) 141, 337–350 (1958).

P. E. Hallett, F. H. C. Marriott, F. C. Rodger, “The relationship of visual threshold to retinal position and area,” J. Physiol. (London) 160, 364–373 (1962).

M. E. Wilson, “Invariant features of spatial summation with changing locus in the visual field,” J. Physiol. (London) 207, 611–622 (1970).

Mem. R. Accad. Sci. Lett. Arti Modena (1)

A. Ricco, “Relazione fra il minimo angolo visuale l’intensita luminosa,” Mem. R. Accad. Sci. Lett. Arti Modena 17, 47–160 (1877).

Nature (3)

H. Wässle, U. Grünert, J. Röhrenbeck, B. B. Boycott, “Cortical magnification factor and the ganglion cell density of the primate retina,” Nature 341, 643–646 (1989).
[CrossRef] [PubMed]

D. M. Dacey, B. B. Lee, “The ‘blue-on’ opponent pathway in primate retina originates from a distinct bistratified ganglion cell type,” Nature 367, 731–735 (1994).
[CrossRef] [PubMed]

A. Roorda, D. R. Williams, “The arrangement of the three cone classes in the living human eye,” Nature 397, 520–522 (1999).
[CrossRef] [PubMed]

Neuron (1)

D. J. Calkins, P. Sterling, “Evidence that circuits for spatial and color vision segregate at the first retinal synapse,” Neuron 24, 313–321 (1999).
[CrossRef] [PubMed]

NeuroReport (1)

S. A. Hagstrom, J. Neitz, M. Neitz, “Variations in cone populations for red–green color vision examined by analysis of mRNA,” NeuroReport 9, 1963–1967 (1998).
[CrossRef] [PubMed]

Proc. Natl. Acad. Sci. USA (1)

D. M. Dacey, M. R. Petersen, “Dendritic field size and morphology of midget and parasol ganglion cells of the human retina,” Proc. Natl. Acad. Sci. USA 89, 9666–9670 (1992).
[CrossRef] [PubMed]

Vision Res. (14)

B. A. Wandell, E. N. Pugh, “A field-additive pathway detects brief-duration, long-wavelength incremental flashes,” Vision Res. 20, 613–624 (1980).
[CrossRef] [PubMed]

B. B. Lee, “Receptive field structure in the primate retina,” Vision Res. 36, 631–644 (1996).
[CrossRef] [PubMed]

B. A. Wandell, E. N. Pugh, “Detection of long-duration, long wavelength incremental flashes by a chromatically coded pathway,” Vision Res. 20, 625–636 (1980).
[CrossRef]

G. Westheimer, “The Maxwellian view,” Vision Res. 6, 669–682 (1966).
[CrossRef] [PubMed]

P. A. Howarth, A. Bradley, “The longitudinal chromatic aberration of the human eye, and its correction,” Vision Res. 26, 361–366 (1986).
[CrossRef] [PubMed]

I. Lie, “Visual detection and resolution as a function of retina locus,” Vision Res. 20, 967–974 (1980).
[CrossRef]

B. Fischer, “Overlap of receptive field centers and representation of the visual field in the cat’s optic tract,” Vision Res. 13, 2113–2120 (1973).
[CrossRef] [PubMed]

K. D. DaVila, W. S. Geisler, “The relative contributions of pre-neural and neural factors to areal summation in the fovea,” Vision Res. 31, 1369–1380 (1991).
[CrossRef] [PubMed]

V. D. Glezer, “The receptive fields of the retina,” Vision Res. 5, 497–525 (1965).
[CrossRef] [PubMed]

A. M. W. Scholtes, M. A. Bouman, “Psychophysical experiments on spatial summation at threshold level of the human peripheral retina,” Vision Res. 17, 867–873 (1977).
[CrossRef] [PubMed]

D. R. Williams, D. I. A. MacLeod, M. M. Hayhoe, “Punctate sensitivity of the blue-sensitive mechanism,” Vision Res. 21, 1357–1375 (1981).
[CrossRef] [PubMed]

C. M. Cicerone, J. L. Nerger, “The relative numbers of long-wavelength-sensitive to middle-wavelength-sensitive cones in the human fovea centralis,” Vision Res. 29, 115–128 (1989).
[CrossRef] [PubMed]

J. L. Nerger, C. M. Cicerone, “The ratio of L cones to M cones in the human parafoveal retina,” Vision Res. 32, 879–888 (1992).
[CrossRef] [PubMed]

R. L. P. Vimal, J. Pokorny, V. C. Smith, S. K. Shevell, “Foveal cone thresholds,” Vision Res. 29, 61–78 (1989).
[CrossRef] [PubMed]

Visual Neurosci. (1)

D. M. Dacey, “Morphology of a small-field bistratified ganglion cells type in the macaque and human retina,” Visual Neurosci. 10, 1081–1098 (1993).
[CrossRef]

Other (5)

Retinal eccentricity values were obtained for ganglion cell density values within 8° of the fovea by use of the correction factor for ganglion cell displacement.54 The ganglion cell density values represent mean values across retinal quadrants. The 0° and 1.5° midget ganglion cell density values were derived from L-cone density values with the assumption of a 2:1 L:M cone ratio. If a different L:M ratio were used, the conclusions drawn from Fig. 7 would not change.

Ahnelt and colleagues (Ref. 21) did not provide an estimate of cone density at 4° and 8° retinal eccentricities. The 10° estimate for S and L cones has been included to show that the density of cones does not change from 10° to 20° retinal eccentricity. Although Curcio et al.23 did not extend their S-cone measurements beyond 8°, in an earlier paper Curcio et al.22 showed that total cone density remained relatively constant from 8° and beyond. Based on this finding, the 20° values were assumed to be the same as the density values at 8° retinal eccentricity. The mean cone density values across retinal quadrants from Curcio et al.22,23 were used in Fig. 6. Ahnelt et al.21 investigated only the temporal quadrant. The numbers of L cones from both studies were derived with the assumption of an L:M cone ratio of 2:1.24,25 If other estimates (e.g., Refs. 26–28) of the L:M cone ratio had been used, the L-cone density function would have shifted only along the y axis. This scalar shift would not affect the analyses presented in Fig. 6 and Table 1.

The term B/Y bistratified ganglion cell is used throughout the paper because it is convenient in anatomy. This nomenclature does not imply that these ganglion cells are responsible for the perception of blue and yellow hues.

D. M. Dacey, “Physiology, morphology and spatial densities of identified ganglion cells types in primate retina,” in Higher-Order Processing in the Visual System, G. R. Bock, J. A. Goode, eds. (Wiley, New York, 1994), pp. 12–34.

T.v.i. functions were also measured at 4°, 8°, and 20° retinal eccentricities. The peripheral functions confirmed that the thresholds measured at the selected background intensity were on the plateau of the t.v.i. function. Test sensitivity functions were also measured at 20° retinal eccentricity under conditions that isolated the S-cone and L-cone mechanisms. As in the fovea, the 20° test sensitivity functions verified the isolation of S- and L-cone mechanisms.

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Figures (9)

Fig. 1
Fig. 1

T.v.i. functions measured in the fovea, shown for conditions that isolated an S-cone mechanism (top) and an L-cone mechanism (bottom) for one observer. Arrows denote the background intensity levels chosen to measure test sensitivities and Ricco’s area.

Fig. 2
Fig. 2

Test sensitivities under conditions that isolated S-cone (top) and L-cone (bottom) mechanisms in the fovea for one observer. Arrows denote the wavelength of the test stimuli chosen to measure Ricco’s area. Solid curves are the fundamentals of DeMarco et al.37

Fig. 3
Fig. 3

Log threshold plotted as a function of log area for the experimental condition that isolated an S-cone mechanism. Each row denotes a different observer; each column depicts a different superior retinal eccentricity. The best-fitting bilinear function is shown in each panel, and the arrow specifies Ricco’s area for that experimental condition.

Fig. 4
Fig. 4

Same as Fig. 3, but for an L-cone mechanism.

Fig. 5
Fig. 5

Log Ricco’s area plotted as a function of superior retinal eccentricity for an S-cone mechanism (open circles) and an L-cone mechanism (filled circles) for three observers.

Fig. 6
Fig. 6

Log Ricco’s area at the retina and reciprocal log cone density plotted as a function of retinal eccentricity: Top, Ricco’s areas for an S-cone mechanism compared with S-cone density; bottom, Ricco’s areas for an L-cone mechanism compared with L-cone density. Each set of open symbols denotes a different observer. Filled squares and circles represent density values from Curcio et al.22,23 and Ahnelt et al.21, respectively.

Fig. 7
Fig. 7

Log Ricco’s area at the retina and reciprocal log ganglion cell density plotted as a function of retinal eccentricity: Top, Ricco’s areas for an S-cone mechanism compared with density of the B/Y bistratified ganglion cells; bottom, Ricco’s areas for an L-cone mechanism compared with density of midget (filled squares) and parasol (filled circles) ganglion cells. Open symbols denote the different observers.

Fig. 8
Fig. 8

Number of ganglion cells that underlie Ricco’s areas across the retina: Top, number of bistratified ganglion cells that underlie Ricco’s areas for an S-cone mechanism; middle (bottom), number of midget (parasol) ganglion cells that underlie Ricco’s areas for an L-cone mechanism. Each set of symbols represents data from a different observer.

Fig. 9
Fig. 9

Diameter of Ricco’s area at the retina and dendritic field size plotted as a function of retinal eccentricity: Top, diameter of Ricco’s areas (open symbols) for an S-cone mechanism compared with dendritic field size of B/Y bistratified ganglion cells (filled circles); bottom, diameter of Ricco’s areas (open symbols) for an L-cone mechanism compared with dendritic field sizes of midget (filled squares) and parasol (filled circles) ganglion cells. Each set of open symbols represents data from a different observer.

Tables (2)

Tables Icon

Table 1 Linear Regressions of Log Cell Density and Log Ricco’s Area for the L-Cone Mechanisma

Tables Icon

Table 2 Linear Regressions of Log Cell Density and Log Ricco’s Area for the S-Cone Mechanisma

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