T. TOMITA
50
kami and Kaneko, cited in Tomita, 1965), and the conductance of the S
cell tends to decrease during response to illumination (Toyoda et al.,
1969). These are exactly what are observed in the photoreceptors.
It should be noted that in spite of the similarities between the S potential and single photoreceptor response there is one distinct difference in
that the S potential has a large area effect or a strong dependence of the
response amplitude upon the retinal area illuminated, while the single
photoreceptor response has substantially no such effect. A convergence
of a great many photoreceptors to S cells is suggested. Lateral electric
connections between S cells can multiply the effect, and the electron
microscope has proved tight junctions between adjacent horizontal cells.
The argument might not be complete without reference to the C
response. The depolarization in the C cell at certain bands of spectrum
appears to be associated with an increase in the conductance of the cell.
Conceivably, the C cell is in a half-facilitated state in the dark, and a
further facilitation is caused by certain wavelengths of light, while disfacilitation is caused by other wavelengths.
B. Responses in Other Cell Types
The intracellular study of single cells in the inner nuclear layer of the
fish retina has become possible only recently by the application of a technique developed for single photoreceptors. Figure 12 illustrates three
response types recorded in this layer by Kaneko and Hashimoto (1969).
They are on, off, and on-off type, being substantially the same as in single
ganglion cells. Some of these cells even respond with impulse spikes
superimposed on depolarizing phases of slow potentials, confirming the
extracellular observation of Brown and Wiesel (1959) in the cat. More
common in the carp, however, are those responding to light with slow
membrane potential changes superimposed by nonunitary spikelike or
oscillatory fluctuations on the depolarizing phases ( Fig. 12).
The organization of the receptive field of these cells also resembles
that of the ganglion cells, as demonstrated in the cat by Brown and Wiesel
(1959). Some have a receptive field of everywhere on, everywhere off, or
everywhere on-off, but others have the concentric receptive field such as
on center-off periphery or the reverse. The response in the periphery is
more easily detectable by an annular light patch. The size of the receptive
field is larger than predicted from the dendritic field of bipolar cells and
seems to be comparable with that of the S potential. From these observations, Kaneko and Hashimoto suspect that the S cells might intervene
between the photoreceptors and these cells to convey information, at least
in the periphery of the receptive field.
50
kami and Kaneko, cited in Tomita, 1965), and the conductance of the S
cell tends to decrease during response to illumination (Toyoda et al.,
1969). These are exactly what are observed in the photoreceptors.
It should be noted that in spite of the similarities between the S potential and single photoreceptor response there is one distinct difference in
that the S potential has a large area effect or a strong dependence of the
response amplitude upon the retinal area illuminated, while the single
photoreceptor response has substantially no such effect. A convergence
of a great many photoreceptors to S cells is suggested. Lateral electric
connections between S cells can multiply the effect, and the electron
microscope has proved tight junctions between adjacent horizontal cells.
The argument might not be complete without reference to the C
response. The depolarization in the C cell at certain bands of spectrum
appears to be associated with an increase in the conductance of the cell.
Conceivably, the C cell is in a half-facilitated state in the dark, and a
further facilitation is caused by certain wavelengths of light, while disfacilitation is caused by other wavelengths.
B. Responses in Other Cell Types
The intracellular study of single cells in the inner nuclear layer of the
fish retina has become possible only recently by the application of a technique developed for single photoreceptors. Figure 12 illustrates three
response types recorded in this layer by Kaneko and Hashimoto (1969).
They are on, off, and on-off type, being substantially the same as in single
ganglion cells. Some of these cells even respond with impulse spikes
superimposed on depolarizing phases of slow potentials, confirming the
extracellular observation of Brown and Wiesel (1959) in the cat. More
common in the carp, however, are those responding to light with slow
membrane potential changes superimposed by nonunitary spikelike or
oscillatory fluctuations on the depolarizing phases ( Fig. 12).
The organization of the receptive field of these cells also resembles
that of the ganglion cells, as demonstrated in the cat by Brown and Wiesel
(1959). Some have a receptive field of everywhere on, everywhere off, or
everywhere on-off, but others have the concentric receptive field such as
on center-off periphery or the reverse. The response in the periphery is
more easily detectable by an annular light patch. The size of the receptive
field is larger than predicted from the dendritic field of bipolar cells and
seems to be comparable with that of the S potential. From these observations, Kaneko and Hashimoto suspect that the S cells might intervene
between the photoreceptors and these cells to convey information, at least
in the periphery of the receptive field.