Spectral Sensitivity of Cones of the Monkey Macaca Fascicularis. Baylor et al. 1987

Phanith & Mathew

  

Breakdown into Vision Three classes of cones Microspectrophotometry (MSP) Direct photocurrent measurement Wavenumber = 1/λ

AIM

To build upon currently known cones spectral sensitivities by determining the sensitivities of

cones to a broader range of wavelengths.

Phototransduction

Kandel

Phototransduction

Kandel

Suction electrode technique Outer segment of cone =

phototransduction

Measured responses to: 440 nm 500 nm 659 nm

Fractional bleaching f = 1 – e-I*A

1. Spectral Sensitivities (Methods)

opsin opsin* opsinbleached

retinaltrans

retinalcis pigment epithelium

phototransductioncascade

2. Spectral Forms Principle of Univariance

Probability of photon absorption determined by wavelength

Amplitude and waveform of response independent of photon wavelength

2 Photon Response

What is the importance of the Principle of Univariance?

Principle of Univariance

Figure 1. Figure 2.

exponential saturation function:

r = rm(1-e-ki)

r = peak amplitude of the responserm = maximal amplitudei = flash photon density

Principle of Univariance

Figure 1. Figure 2.

exponential saturation function:

r = rm(1-e-k(λ)i)

r = peak amplitude of the responserm = maximal amplitudei = flash photon densityk(λ) = proportionality constant

S

3 & 4. Maximum Sensitivities and Fitting

M LLegend:

6th order polynomial:

Figure 3a. Figure 3b.

Limitations:• Top region is flat

• True shape must be assumed

5. Subclasses of Cones Linear regression Derived from:

15 L cones from 6 macaques 19 M cones from 7 macaques 4 S cones from 3 macaques

5. Subclasses of Cones

Figure 1. The genetics of normal and defective color vision. Neitz 2011

6. Psychophysical Results

Figure 4.

λ𝑥=645nmλ 𝑦=526 nmλ𝑧=444 nm

Monitor and Cone Spaces

Cone Isolating Stimuli

Comparisons of Spectra estimate of human cones

spectral sensitivities note:

smooth curve = Π mechanisms points = adjusted sensitivity

points

adjusted for: macular pigment lens screening

L

M

S

Discussion: