1. ANATOMY AND PHYSIOLOGY O F THE CENTRAL NERVOUS SYSTEM
41
the spectral sensitivity of rcd-green, yellow-blue, and red-blue units
may result from the interaction betwcen only two different classes of
cones, each set of which contains one of the three visual pigments
(Jacobson, 1964a,b). These results are in agreement with the retinal
electrophysiological and chemical rcsults derived from studies of the
retina.
E. Interhemispheric Transfer of Visual Information
The study of interhcmisphcric transfer of visual information between
the hemispheres of the optic tectum has played a major role in the advancement of the knowledge of the function of the optic tcctum of fish.
This is particularly interesting in respect to the problem of how infonnation in one part of the brain is retrieved and becomes available to other
parts of the brain. In general, information prcsented to one eye and
stored in the contralateral tectal hemisphere transfers to the ipsilateral
hemisphere thereby enabling the animal to respond appropriately using
only the untrained or naive eye. The optic nerve of the fish appears to
be completely decussated: the right eye projecting to only the left tectal
hemisphere and the left eye projecting to only the right optic tectum
(Aliens Kappers et al., 1960; Papez, 1929). Therefore, the fish appears
to be an excellent animal for studies on storage and retrieval of visual
information in the central nervous system. Tectal transfer in the fish docs
not appear to be perfectly developed (Sperry and Clark, 1949). The
failure of goldfish in the interocular transfer of visual discrimination in
shuttle boxes, however, results from the failure of the transfer of visual
motor learning ( McCleary, 1951, 1960). If the response measure is
cardiac deceleration and does not involve a visual motor response, interocular transfer of color visual information is excellent ( Bernstein,
1962). From these studies on interocular transfer of visual input in the
fish it appears that under certain conditions there is a significant degree
of interocular transfer and that the completeness of the transfer is not a
problem of perception but a problem in sensory-motor integration.
The cichlid fish, Astronotus ocellatus, were trained monocularly to
make a hue discrimination (Arora, 1959; Arora and Sperry, 1961). Following acquisition of the problem, the optic nerve of the trained eye
or the tectal projection of the trained eye was transected or extirpated.
The untrained or naive eye was then testcd, and the fish responded
appropriately. It was postulated that such interocular transfers may
result from the establishment of a dual memory trace system, one on each
side of the brain, or from the rctrieval by the untrained side from
41
the spectral sensitivity of rcd-green, yellow-blue, and red-blue units
may result from the interaction betwcen only two different classes of
cones, each set of which contains one of the three visual pigments
(Jacobson, 1964a,b). These results are in agreement with the retinal
electrophysiological and chemical rcsults derived from studies of the
retina.
E. Interhemispheric Transfer of Visual Information
The study of interhcmisphcric transfer of visual information between
the hemispheres of the optic tectum has played a major role in the advancement of the knowledge of the function of the optic tcctum of fish.
This is particularly interesting in respect to the problem of how infonnation in one part of the brain is retrieved and becomes available to other
parts of the brain. In general, information prcsented to one eye and
stored in the contralateral tectal hemisphere transfers to the ipsilateral
hemisphere thereby enabling the animal to respond appropriately using
only the untrained or naive eye. The optic nerve of the fish appears to
be completely decussated: the right eye projecting to only the left tectal
hemisphere and the left eye projecting to only the right optic tectum
(Aliens Kappers et al., 1960; Papez, 1929). Therefore, the fish appears
to be an excellent animal for studies on storage and retrieval of visual
information in the central nervous system. Tectal transfer in the fish docs
not appear to be perfectly developed (Sperry and Clark, 1949). The
failure of goldfish in the interocular transfer of visual discrimination in
shuttle boxes, however, results from the failure of the transfer of visual
motor learning ( McCleary, 1951, 1960). If the response measure is
cardiac deceleration and does not involve a visual motor response, interocular transfer of color visual information is excellent ( Bernstein,
1962). From these studies on interocular transfer of visual input in the
fish it appears that under certain conditions there is a significant degree
of interocular transfer and that the completeness of the transfer is not a
problem of perception but a problem in sensory-motor integration.
The cichlid fish, Astronotus ocellatus, were trained monocularly to
make a hue discrimination (Arora, 1959; Arora and Sperry, 1961). Following acquisition of the problem, the optic nerve of the trained eye
or the tectal projection of the trained eye was transected or extirpated.
The untrained or naive eye was then testcd, and the fish responded
appropriately. It was postulated that such interocular transfers may
result from the establishment of a dual memory trace system, one on each
side of the brain, or from the rctrieval by the untrained side from