40
T. TOMITA
The PI11 is of dual nature as earlier suggested by Granit (1947).
The separation of PIII into two subcomponents was achieved by a
technique of fractional depth recording of the ERG (Murakami and
Kaneko, 1966). The one subcomponent is termed the “distal PIII” and
localized in the receptors themselves. The other termed the “proximal
PIII” originates in some structures in the inner nuclear layer. The latency
of the proximal PI11 is several milliseconds longer than that of the distal
PIII. The proximal PIII is more susceptible to various agents than the
distal PIII. The proximal PI11 may be a transretinal manifestation either
of the S potential (Byzov, 1962) or of the activity of the cell types in
the inner nuclear layer that respond to light with hyperpolarization (see
Section V ) , or probably of both.
One aspect of the PI11 that made Granit hesitate to localize it in the
receptors was its polarity. The PI11 has a polarity just opposite to what
one predicts from other receptors including invertebrate photoreceptors.
While it is general that the receptors, when excited, are depolarized to
form an electric field making their distal tips negative, the polarity of
PI11 makes them positive instead of negative. According to the recent
observations on single rods and cones with intracellular micropipettes,
however, the unusual polarity of the electric field around the vertebrate
photoreceptors is attributed to their being hyperpolarized by light ( see
Section IV, B ) .
111. RESPONSE OF SINGLE GANGLION CELLS
A. Response Types
The response types of single ganglion cells in the fish are the same as
in other vertebrates such as the frog (Hartline, 1938) and the cat ( KuHer,
1953). They are either on type giving a burst of impulses when the light
is turned on, the o# type giving a burst of impulses when the light turned
off, or the o*o# type which responds with a burst of impulses at both
onset and cessation of light. Intracellular recording reveals that in the on
type the cell is depolarized during illumination, while in the off type the
cell is hyperpolarized during illumination and depolarized following the
cessation of light. In the on-off type a depolarization occurs at both on
and off. It is obvious that the ganglion cell functions according to the
general plan of neurons which are under excitatory and inhibitory presynaptic controls.
T. TOMITA
The PI11 is of dual nature as earlier suggested by Granit (1947).
The separation of PIII into two subcomponents was achieved by a
technique of fractional depth recording of the ERG (Murakami and
Kaneko, 1966). The one subcomponent is termed the “distal PIII” and
localized in the receptors themselves. The other termed the “proximal
PIII” originates in some structures in the inner nuclear layer. The latency
of the proximal PI11 is several milliseconds longer than that of the distal
PIII. The proximal PIII is more susceptible to various agents than the
distal PIII. The proximal PI11 may be a transretinal manifestation either
of the S potential (Byzov, 1962) or of the activity of the cell types in
the inner nuclear layer that respond to light with hyperpolarization (see
Section V ) , or probably of both.
One aspect of the PI11 that made Granit hesitate to localize it in the
receptors was its polarity. The PI11 has a polarity just opposite to what
one predicts from other receptors including invertebrate photoreceptors.
While it is general that the receptors, when excited, are depolarized to
form an electric field making their distal tips negative, the polarity of
PI11 makes them positive instead of negative. According to the recent
observations on single rods and cones with intracellular micropipettes,
however, the unusual polarity of the electric field around the vertebrate
photoreceptors is attributed to their being hyperpolarized by light ( see
Section IV, B ) .
111. RESPONSE OF SINGLE GANGLION CELLS
A. Response Types
The response types of single ganglion cells in the fish are the same as
in other vertebrates such as the frog (Hartline, 1938) and the cat ( KuHer,
1953). They are either on type giving a burst of impulses when the light
is turned on, the o# type giving a burst of impulses when the light turned
off, or the o*o# type which responds with a burst of impulses at both
onset and cessation of light. Intracellular recording reveals that in the on
type the cell is depolarized during illumination, while in the off type the
cell is hyperpolarized during illumination and depolarized following the
cessation of light. In the on-off type a depolarization occurs at both on
and off. It is obvious that the ganglion cell functions according to the
general plan of neurons which are under excitatory and inhibitory presynaptic controls.