- •Contents
- •Acknowledgements
- •1 Introduction
- •1.1 Roots of the duplicity theory of vision: Ancient Greeks
- •1.2 Further development of the duplicity theory
- •Part I The development of the basic ideas of the duplicity theory from Newton to G. E. Müller
- •2 The Newton tradition
- •2.5 Conclusions
- •2.7 Maxwell: triplicity of colour vision proved
- •2.8 Helmholtz: the Young-Helmholtz colour theory
- •3 The Schultze tradition
- •3.1 The duplicity theory of Max Schultze
- •3.2 Evidence in favour of the theory
- •3.3 One or several types of cone?
- •3.5 Boll: discovery of rhodopsin as a visual photopigment
- •3.7 Phototransduction of rhodopsin
- •3.9 The duplicity theory of Parinaud
- •3.12 The duplicity theory of von Kries
- •1. Lights that match in day vision may differ in twilight vision: the Purkinje phenomenon.
- •2. Anatomical interpretation of the theory. Cones and Rods. Uniqueness of the fovea. Rhodopsin.
- •3. Isolation of twilight vision. Congenital, total colour-blindness. Nyctalopia. On comparative anatomy.
- •3.13 An attempt to unify the theories of Schultze and Young-Helmholtz
- •4 The Goethe tradition: the phenomenological approach
- •4.1 Phenomenological analysis may reveal underlying material processes
- •4.2 The colour theory of J. W. von Goethe
- •4.4 The colour theory of Ewald Hering
- •4.6 Contributions of Hering
- •5.1 The colour theory of Tschermak
- •5.2.2 Cones may inhibit regeneration of rhodopsin
- •5.2.3 Rods subserving chromatic colour vision
- •5.2.4 Three types of cones and five pairs of opponent processes
- •5.2.5 Activation of opponent processes by P1, P2 and P3
- •5.2.6 The P1 system
- •5.2.7 The P2 system
- •5.2.8 The P3 system
- •6 The duplicity theory of Polyak
- •6.1 Trichromacy of colour vision explained by three types of bipolar cell
- •6.2 Midget ganglion cells as synthesizers
- •6.3 The specific fibre-energy doctrine questioned
- •6.5 Common pathways of rods and cones
- •6.6 Explanations of acuity and sensitivity differences between rods and cones
- •6.7 The functional potentials of the synaptic arrangement
- •7.1 The electrical responses to light stimuli in single optic nerve fibres
- •7.2 The electrical responses in single optic nerve fibres of Limulus
- •7.3 The electrical responses in single optic nerve fibres of the frog
- •8 The duplicity theory of R. Granit
- •8.1 Supporting evidence for the duplicity theory from the ERG technique
- •8.2 The dominator-modulator theory
- •8.2.1. The trichromatic colour theory challenged
- •9.1 The duplicity theory of Willmer
- •9.1.1 Colour vision explained by two types of rod and one type of cone
- •9.3 Ivar Lie: interactions between rod and cone functions at mesopic intensity
- •9.3.1 Psychophysical experiments
- •9.3.2 The colour-mixing hypothesis
- •9.3.3 An alternative explanatory model
- •10 Status of the duplicity theory in the mid 1960s and its further development
- •Part III Chromatic rod vision: a historical account
- •11 Night vision may appear bluish
- •12 Mechanisms of chromatic rod vision in scotopic illumination
- •12.1 All principle hues may be observed in scotopic vision
- •12.2 Scotopic contrast colours are triggered by rod signals
- •12.3 Scotopic contrast colours depend on selective chromatic adaptation of cones
- •12.4 Scotopic hues explained
- •13 Rod-cone interactions in mesopic vision
- •13.1 Rod-cone interactions under mesopic conditions in a chromatically neutral state of adaptation
- •13.2 Rod-cone interactions under mesopic conditions in a chromatic state of adaptation
- •14 Further exploration of chromatic rod vision
- •14.1 Contribution of J. J. McCann and J. L. Benton
- •14.2 Contribution of P. W. Trezona
- •14.3 Contribution of C. F. Stromeyer III
- •14.4 Contribution of S. Buck and co-workers
- •14.5. Contribution of J. L. Nerger and co-workers
- •Part IV Theories of sensitivity regulation of the rod and cone systems: a historical account
- •15 Introduction
- •16 Early photochemical explanations
- •17 Contribution of S. Hecht
- •17.2 Supporting evidence obtained from invertebrates
- •17.3 Supporting evidence obtained from psychophysical experiments
- •18 Contribution of G. Wald: photochemical sensitivity regulation mechanisms of rods and cones
- •18.2 Serious challenges to the photochemical theory
- •18.3 The neural factor refuted
- •19 Relationship between amount of rhodopsin and sensitivity during dark adaptation
- •19.1 Results of Tansley
- •19.2 Results of Granit
- •19.5 A logarithmic relationship between sensitivity and amount of bleached photopigment
- •19.7 Contribution of W.A.H. Rushton: relationship between sensitivity and amount of bleached rhodopsin in humans
- •20 Post-receptor sensitivity regulation mechanisms
- •20.1 Psychophysical evidence
- •20.2 Anatomical and electrophysiological evidence
- •21.1 Each receptor type has a separate and independent adaptation pool
- •21.2 Are light and dark adaptation really equivalent?
- •21.3 A decisive experiment
- •21.4 The adaptation mechanisms explored by the after-flash technique
- •22 Contribution of H. B. Barlow
- •22.1 Dark and Light adaptation based on similar mechanisms
- •22.2 Both noise and neural mechanisms involved
- •22.3 Evidence in support of the noise theory
- •22.4 Opposing evidence
- •22.5 Sensitivity difference between rods and cones explained
- •23 Rushton and Barlow compared
- •24.1 Contribution of T.D. Lamb
- •24.2 The search for a new formula
- •24.3 Differences between rod and cone dark adaptation
- •24.4 Light and dark adaptation are not equivalent
- •24.5 Allosteric regulation of dark adaptation
- •24.6 A search for the allosteric adaptation mechanisms
- •25 Several mechanisms involved in sensitivity regulation
- •26 Sensitivity regulation due to rod-cone interaction
- •27 Modern conceptions of sensitivity regulation
- •Part V Factors that triggered the paradigm shifts in the development of the duplicity theory
- •References
- •Index
20 development of the basic ideas of the duplicity theory
the triplicity in the retina. This profound new insight deserves to be ranked as the second major paradigm shift in vision research.
2.8 Helmholtz: the Young-Helmholtz colour theory
Helmholtz (1867) immediately accepted the colour-mixture data of Maxwell and, as a consequence, the trichromatic colour theory of Young (1807). He summarized its main theoretical statements as follows (Helmholtz, 1867, pp. 291–292):
1. There exist three different types of nerve fibre in the eye. Activation of one gives rise to red sensation, the other green and the third violet. (In this statement Helmholtz extended the specific nerve-energy doctrine of Johannes Müller (1840) to a doctrine of specific fibre energy operating within a single sense organ.)
2. The three types of fibre are activated to different degrees by different wavelengths in that red-related fibres are most strongly activated by the longest wavelengths, the green-related fibres by middle wavelengths, while the violet-related fibres are most strongly activated by the shortest wavelengths.
3. Pure yellow results from moderate activity in redand green-related fibres and a small activation of violet-related fibres, while blue is produced by moderate activities of greenand violet-related fibres and a small activation of red-related fibres. Finally, white sensation is produced when the three different typses of nerve fibre are activated to about the same degree.
4. The nerve activities of the three different types of fibre are qualitatively different and transmitted to the brain without interacting with each other.
As an alternative possibility, Helmholtz (1867, p. 292) pointed out that the triplex mechanism might be based on three independent and qualitatively different processes within each fibre. Under this alternative, an essential cause of the triplicity and colour quality would be seated in each nerve fibre.
Later, in the 1896 edition of his ‘Handbuch’, however, he, in accord with Newton (1675, 1730), attributed the different types
the newton tradition 21
of sensory quality solely to the brain. Here he assumed that there were no qualitative differences as regards nerve conduction, so that the nerve fibres were like telegraph wires which passively conduct electricity.
Of course, Helmholtz knew that the ether waves of light did not directly activate the nerve fibres. Instead, he assumed that the nerve activity was generated by processes in light-sensitive elements, and that these elements had to be cones, since only cones were found in the central fovea, where vision was best developed, and also because vision deteriorated with eccentricity, where the number of rods relative to cones increased. The transformation of light to nerve impulses (the phototransduction in the receptors) was, however, completely unknown in the 1860s (Helmholtz, 1867, pp. 214–215).