20
JERALD J. BERNSTEIN
equal brightness and tested with red and green stimuli of differing brightnesses were found to respond only to the brightness differences of the
test stimuli (Bernstein, 1961b). If normal fish learned to discriminate
stimuli that differed in both hue and brightness, their ability to discriminate was impaired when they were subsequently tested with stimuli
having identical hues but reversed brightness. Such a reversal test did
not confuse the operated fish since they persisted in reacting to the
brightness differences despite the confounding of hue-brightness relationships ( Bernstein, 1961b).
Forebrain-ablated goldfish trained to gray stimuli of varying brightnesses and tested on black and white stimuli were found to make
brightness discriminations whereas normal fish did not make this discrimination. Furthermore, fish lacking a forebrain were able to generalize
to a different brightness problem ( Bernstein, 1961a).
Interocular transfer of a hue discrimination was made by normal
goldfish and goldfish with the forebrain ablated contralateral to the
trained eye. However, ablation of the forebrain homolateral to the
trained eye or bilateral forebrain ablation and subsequent immediate
training and testing (within 10 min) resulted in a loss in ability to make
an intcrocular transfer of a hue discrimination. Training and testing
preceded by a 4-hr interval after complete telencephalic ablation resulted
in spontaneous recovery of color visual function and interocular transfer
of an acquired hue discrimination ( Bernstein, 1962, 1963). These results
demonstrate that the telencephalon is not essential for color vision but
does partially function in the integration of color visual information.
This color visual integrating function of the telencephalon can be
assumed by lower brain centers. Spontaneous recovery of nervous system
function is a well-known phenomenon in vertebrates (Ruch, 1958).
G. Telencephalon and Learning
Ablation of the telencephalon of goldfish greatly impaired or prevented the acquisition of an instrumental response (one-way conditioned
avoidance), abolished retention of the response in animals when the
task was previously learned, and greatly reduced resistance to extinction
in one-way avoidance learning ( Hainsworth et al., 1967). However,
forebrainless goldfish eventually do learn the response. Tilapa macrocephala have been trained to escape in conditioned avoidance training
by passing through a 4-cm hole to avoid shock [unconditioned stimulus
( U S ) ] in response to the onset of a light [conditioned stimulus (CS)].
Animals were trained to avoid the shock within 2.5 sec CS-US interval
JERALD J. BERNSTEIN
equal brightness and tested with red and green stimuli of differing brightnesses were found to respond only to the brightness differences of the
test stimuli (Bernstein, 1961b). If normal fish learned to discriminate
stimuli that differed in both hue and brightness, their ability to discriminate was impaired when they were subsequently tested with stimuli
having identical hues but reversed brightness. Such a reversal test did
not confuse the operated fish since they persisted in reacting to the
brightness differences despite the confounding of hue-brightness relationships ( Bernstein, 1961b).
Forebrain-ablated goldfish trained to gray stimuli of varying brightnesses and tested on black and white stimuli were found to make
brightness discriminations whereas normal fish did not make this discrimination. Furthermore, fish lacking a forebrain were able to generalize
to a different brightness problem ( Bernstein, 1961a).
Interocular transfer of a hue discrimination was made by normal
goldfish and goldfish with the forebrain ablated contralateral to the
trained eye. However, ablation of the forebrain homolateral to the
trained eye or bilateral forebrain ablation and subsequent immediate
training and testing (within 10 min) resulted in a loss in ability to make
an intcrocular transfer of a hue discrimination. Training and testing
preceded by a 4-hr interval after complete telencephalic ablation resulted
in spontaneous recovery of color visual function and interocular transfer
of an acquired hue discrimination ( Bernstein, 1962, 1963). These results
demonstrate that the telencephalon is not essential for color vision but
does partially function in the integration of color visual information.
This color visual integrating function of the telencephalon can be
assumed by lower brain centers. Spontaneous recovery of nervous system
function is a well-known phenomenon in vertebrates (Ruch, 1958).
G. Telencephalon and Learning
Ablation of the telencephalon of goldfish greatly impaired or prevented the acquisition of an instrumental response (one-way conditioned
avoidance), abolished retention of the response in animals when the
task was previously learned, and greatly reduced resistance to extinction
in one-way avoidance learning ( Hainsworth et al., 1967). However,
forebrainless goldfish eventually do learn the response. Tilapa macrocephala have been trained to escape in conditioned avoidance training
by passing through a 4-cm hole to avoid shock [unconditioned stimulus
( U S ) ] in response to the onset of a light [conditioned stimulus (CS)].
Animals were trained to avoid the shock within 2.5 sec CS-US interval