42
JERALD J. BERNSTEIN
memory traces established in the subtectal centers on the trained side.
Interocular transfer of a pattern discrimination using various types
of discriniinanda was complete in goldfish when appropriate controls
were carried out ( Schulte, 1957; Shapiro, 1965). These controls were
for orientational difficulties, specific response biases associated with the
monocular vision, restriction of the visual field, and general learning
about the experimental situation which was not task specific (Shapiro,
1965).
Although the forcbrain commissures were not essential for the transfer of color visual information in goldfish (Bernstein, 1962), the tectal
commissure was necessary for the interocular transfer of pattern discrimination in the Oscar, Astronotus ocellatus (Mark, 1966). Astronotus
were trained to respond by jumping out of the watcnr for food reward to
different patterns floating on the surface of an aquarium. Animals learned
this task binocularly or monocularly (one eye covered). Animals trained
monocularly demonstrated interocular transfer. Following training and
subsequent transection of the tectal cominissure the fish failed to make
the interocular transfer of the discrimination. Normal fish also were
trained to the patterns with one eye covered and then trained on the
reversal problem with the naive eye (trained eye covered), Following
acquisition of reversal learning by the naive eye, the eye that was
originally trained demonstrated a strong prefercnce for the stimuli on
which the naive eye had been trained. Initial learning with one eye then
was effectively replacing the original problem through interocular transfer of experience gained through the other eye.
Attempts were made to produce chronic lesions of the posterior
commissure in Astronotus; unfortunately, the animals did not survive
(Mark, 1966). It would be of interest to study the transfer of information in the posterior commissure and the commissure which lies above it,
the geniculate commissure. Sincc the transection of the tectal comniissure resulted in the loss of interocular transfer of pattern and thc strong
suspicion that the posterior commissure was involved with interocular
transfer, it is possible that there are two anatomically distinct systems
within the mesencephalon of fish for the interocular transfer of visual
information ( Mark, 1966). Although thcrc was no histological verification of the lesion, interocular transfer of a conditioiicd avoidance response in goldfish was blocked by postcrior comniissure transcction prior
to monocular training ( Ingle, 196%).
Electrophysiological recordings from tectal coniniissural fibers in
goldfish and Astronotus ocellatus h a w not shown any clcar evidence that
the tectal commissural cells respond to small spots of light or small dark
objects moving anywhere within the visual field of either eye (Mark
JERALD J. BERNSTEIN
memory traces established in the subtectal centers on the trained side.
Interocular transfer of a pattern discrimination using various types
of discriniinanda was complete in goldfish when appropriate controls
were carried out ( Schulte, 1957; Shapiro, 1965). These controls were
for orientational difficulties, specific response biases associated with the
monocular vision, restriction of the visual field, and general learning
about the experimental situation which was not task specific (Shapiro,
1965).
Although the forcbrain commissures were not essential for the transfer of color visual information in goldfish (Bernstein, 1962), the tectal
commissure was necessary for the interocular transfer of pattern discrimination in the Oscar, Astronotus ocellatus (Mark, 1966). Astronotus
were trained to respond by jumping out of the watcnr for food reward to
different patterns floating on the surface of an aquarium. Animals learned
this task binocularly or monocularly (one eye covered). Animals trained
monocularly demonstrated interocular transfer. Following training and
subsequent transection of the tectal cominissure the fish failed to make
the interocular transfer of the discrimination. Normal fish also were
trained to the patterns with one eye covered and then trained on the
reversal problem with the naive eye (trained eye covered), Following
acquisition of reversal learning by the naive eye, the eye that was
originally trained demonstrated a strong prefercnce for the stimuli on
which the naive eye had been trained. Initial learning with one eye then
was effectively replacing the original problem through interocular transfer of experience gained through the other eye.
Attempts were made to produce chronic lesions of the posterior
commissure in Astronotus; unfortunately, the animals did not survive
(Mark, 1966). It would be of interest to study the transfer of information in the posterior commissure and the commissure which lies above it,
the geniculate commissure. Sincc the transection of the tectal comniissure resulted in the loss of interocular transfer of pattern and thc strong
suspicion that the posterior commissure was involved with interocular
transfer, it is possible that there are two anatomically distinct systems
within the mesencephalon of fish for the interocular transfer of visual
information ( Mark, 1966). Although thcrc was no histological verification of the lesion, interocular transfer of a conditioiicd avoidance response in goldfish was blocked by postcrior comniissure transcction prior
to monocular training ( Ingle, 196%).
Electrophysiological recordings from tectal coniniissural fibers in
goldfish and Astronotus ocellatus h a w not shown any clcar evidence that
the tectal commissural cells respond to small spots of light or small dark
objects moving anywhere within the visual field of either eye (Mark