Biology Reference
In-Depth Information
centripetal impulses. Also, he stressed the interesting possibility that
the output reactions of a given neuron, both with regard to quantity
and quality, might depend not so much upon the input as upon its
own innate disposition, as illustrated by the
bioelectrical
output of
the photoreceptors elicited by the
light
energy input.
Polyak's theory of rod and cone functions, although highly
speculative, was based on far more accurate histological data than
the theory of Schultze. His results strongly indicated that some of
the basic assumptions of Schultze had to be reformulated. Thus, he
could find no evidence of three distinct varieties of minute structures
that could serve as chromatic analyzers in the cone receptors and also
showed that several of the bipolar and ganglion cell varieties were
connected to both the rod and cone systems. Indeed, Polyak's own
functional interpretation of the histological structure of the retina
of the primate made it seem possible that colour vision, sensitivity
regulation and acuity performances to a large extent were controlled
by bipolar, horizontal, amacrine and ganglion cells and their synaptic
relations.
Milestones in the further development of our understanding
of the function of rods and cones are represented by the works of
H. K. Hartline, S. W. Kuffler and R. Granit.
