38
JERALD J. BERNSTEIN
response of the on unit was a sustained discharge when a spot of light
was placed in any part of the receptive field. Diameters of the receptive
field ranged from 15” to more than 40”. Off units were recorded from
all the fiber layers of the tectum but again were most frequently found
in layer D (Jacobson and Gaze, 1964).
The organization of the retinotectal projection within the optic
tectum of teleost fish was similar in all species observed (Jacobson
and Gaze, 1964; Schwassman and Kruger, 1965; Sutterlin and Prosser,
1968). The only variation appeared to be in the bluegill which departed
from the strict linearity of the representation of the visual projection
upon the tectum. In the bluegill distances between the receptive field
were compressed for a unit discharging to a stimulus below the horizontal meridian (Schwassman and Kruger, 1965).
Retinal unit responses have been recorded from the optic nerve after
stimulation of the eye by means of perimetry (Mark and Davidson,
1966). The units in the retina gave the same type of response as the
units in the tectum. They were sensitive to small spots of light in a
limited visual field or to the movement of small dark or light objects in
and out of the receptive field. This, together with the data on the
retinal response to color in which the units of the retina (MacNichol
et al., 1961) responded like the units in the tcctum (Jacobson, 1964a,b),
demonstrates that the neurons of the optic tectum of the goldfish do not
respond differently from the primary input from thc optic nerve. Information recorded from the optic chiasma (Jacobson and Gaze, 1961) and
recordings from the optic tcctum by other authors show that the response
latency is locked to the response time of the primary retinal input.
Computer-averaged signals from the unanesthetized visual pathway
exhibit great sensitivity to all electrical events without the sampling bias
inherent to unit recording techniques. Electrorctinograni (ERG), fast
retinal potential (FRP), and tectal evoked response (TER) were recorded at three stimulus luminances, 800, 1000, and 4000 foot-lamberts
(ft-L) (Fig. 6 ) . Light stimuli were 50 psec in duration (Dawson and
Bernstein, 1970). All signal component amplitudes of response of the
ERG and FRP were directly (logarithmically) related to luminance
“brightness of stimulus” as were the threc early components of the
tectal response. The triple peak tectal signal was suggestive of fibers of
three different conduction velocities and thus of a triniodal optic nerve
fibcr spectrum. In support of this finding, clectrical stimulation of the
optic nerve produced n triple peaked compound action potential. Thc
amplitude of later tectal signals ( following triple peaked rc’sponse ) wiis
not related to luminance of the stimulus since some tectal signals were
observed at 800 and 1000 ft-L but wcre absciit or diminished at 4000
JERALD J. BERNSTEIN
response of the on unit was a sustained discharge when a spot of light
was placed in any part of the receptive field. Diameters of the receptive
field ranged from 15” to more than 40”. Off units were recorded from
all the fiber layers of the tectum but again were most frequently found
in layer D (Jacobson and Gaze, 1964).
The organization of the retinotectal projection within the optic
tectum of teleost fish was similar in all species observed (Jacobson
and Gaze, 1964; Schwassman and Kruger, 1965; Sutterlin and Prosser,
1968). The only variation appeared to be in the bluegill which departed
from the strict linearity of the representation of the visual projection
upon the tectum. In the bluegill distances between the receptive field
were compressed for a unit discharging to a stimulus below the horizontal meridian (Schwassman and Kruger, 1965).
Retinal unit responses have been recorded from the optic nerve after
stimulation of the eye by means of perimetry (Mark and Davidson,
1966). The units in the retina gave the same type of response as the
units in the tectum. They were sensitive to small spots of light in a
limited visual field or to the movement of small dark or light objects in
and out of the receptive field. This, together with the data on the
retinal response to color in which the units of the retina (MacNichol
et al., 1961) responded like the units in the tcctum (Jacobson, 1964a,b),
demonstrates that the neurons of the optic tectum of the goldfish do not
respond differently from the primary input from thc optic nerve. Information recorded from the optic chiasma (Jacobson and Gaze, 1961) and
recordings from the optic tcctum by other authors show that the response
latency is locked to the response time of the primary retinal input.
Computer-averaged signals from the unanesthetized visual pathway
exhibit great sensitivity to all electrical events without the sampling bias
inherent to unit recording techniques. Electrorctinograni (ERG), fast
retinal potential (FRP), and tectal evoked response (TER) were recorded at three stimulus luminances, 800, 1000, and 4000 foot-lamberts
(ft-L) (Fig. 6 ) . Light stimuli were 50 psec in duration (Dawson and
Bernstein, 1970). All signal component amplitudes of response of the
ERG and FRP were directly (logarithmically) related to luminance
“brightness of stimulus” as were the threc early components of the
tectal response. The triple peak tectal signal was suggestive of fibers of
three different conduction velocities and thus of a triniodal optic nerve
fibcr spectrum. In support of this finding, clectrical stimulation of the
optic nerve produced n triple peaked compound action potential. Thc
amplitude of later tectal signals ( following triple peaked rc’sponse ) wiis
not related to luminance of the stimulus since some tectal signals were
observed at 800 and 1000 ft-L but wcre absciit or diminished at 4000