Biology Reference
In-Depth Information
received from the three or four different kinds of bipolar cells. This
presumption, of course, clearly violated the specific fibre-energy doctrine
of Helmholtz (
1896
) and also appeared to be in conflict with electro-
physiological recordings from single nerve fibres where only one kind
of electrical activity had been recorded (Graham & Hartline,
1935
). In
opposition to the doctrine of Helmholtz, however, Polyak stressed the
possibility that the mode of reaction of a nerve fibre might be 'plastic'.
Thus, he suggested that a great variety of bioelectrical and chemical
processes of different kinds might take place in the neuro-plasma of a
nerve fibre while eliciting substantially the same outward electrical
manifestation registered by the microelectrode. Different qualities might
also be coded by special groupings of the impulses in time, for example,
by rhythmical groupings not yet known. Furthermore, in defence of
his colour theory, Polyak pointed to the fact that the retina had a very
complex structure and was made up of basically the same nerve cells as
found in the brain, where evidently different qualities could emerge. He
did admit, however, that little was yet known with regard to the ability
of the same neuron or nerve fibre to generate and to conduct different
modalities and qualities of dynamical changes.
6.4 Applications of Polyak's colour theory
Polyak held that his colour theory, because of its general character,
was applicable to a number of other colour theories in addition to
Young's trichromatic colour theory. The basic requirements of
Hering's opponent colour theory, for example, could be satisfied by
the assumption that transmission of each dissimilation- assimila-
tion process (the red-green, yellow-blue and white-black antagonistic
processes) was carried out by one of the three bipolar varieties.
Furthermore, Polyak argued that his colour theory provided
new insight into the material causes of various forms of colour-
blindness: protanopia, deuteranopia, tritanopia, various forms of
anomalous trichromatism, monochromatism, and also partial and
complete blindness. Instead of failures of cones, one, two or all three
