1. ANATOMY AND PHYSIOLOGY OF THE CENTRAL NERVOUS SYSTEM
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reproductive behavioral responses ( Segaar, 1965). In a series of experiments, Segaar removed discrete portions of the stickleback telencephalon
and found differential suppression of aggressive, sexual, and parental
behavior ( Segaar, 1956, 1961, 1965; Segaar and Nieuwenhuys, 1963).
After removal of either the rostra1 or the lateral portion of the telencephalon aggression was greatly suppressed, sexual activity was short in
duration, and parental care was rather extensive. However, after ablation
of the medial caudal portion-of the telencephalon these patterns appeared
to be reversed, with elevated aggression, continuous sex drive, and low
parental activity. Following medial lesions of the telencephalon, sticklebacks demonstrated rising aggressive behavior and depression of sex
drive, but otherwise they appeared to be normal. Lesions in the extreme
medial part of the caudal medial and dorsal medial areas of the telencephalon resulted in disinhibition of parental activity while aggression
and sex drive were normal (Segaar, 1965).
These data show that specific telencephalic lesions result in disruption of the balance of specific behavioral responses such as aggressive
behavior, sexual activity, and parental behavior in sticklebacks ( Segaar,
1965). The telencephalon appears to function as an organizer and
integrator of segments of innate (DNA contingent) behavior and maintains aggression, sexual activity, and parental behavior of fishes in the
proper balance to insure successful reproduction of the species.
F. Specific Sensory Deficits following Telencephalic Ablation
Color vision in goldfish has been studied using cardiac deceleration,
a conditioned autonomic response, as the measure of discrimination
( h4cCleary and Bernstein, 1959). After establishing the relative brightnesses of two pairs of red and green stimulus patches as perceived by
the fish, these same stimulus patches were used to determine whether a
subsequent discrimination by the fish was based on hue or brightness.
Stimulus generalization was used as a method of evaluating what aspect
of the stimulus was used by the fish in learning a given discrimination.
Goldfish were found to be capable of red-green hue discrimin a t' ion
under experimental conditions which ruled out the possibility that
brightness cues were being employed. The goldfish was also found to
be capable of stimulus generalization involving either hue or brightness
characteristics of the stimuli ( McClcary and Brrnstein, 1959).
Forebrain extirpation resulted in a selective suppression of the color
visual discrimination in goldfish. Immediately following complete bilateral telencephalic ablation, animals trained to red and green stimuli of
19
reproductive behavioral responses ( Segaar, 1965). In a series of experiments, Segaar removed discrete portions of the stickleback telencephalon
and found differential suppression of aggressive, sexual, and parental
behavior ( Segaar, 1956, 1961, 1965; Segaar and Nieuwenhuys, 1963).
After removal of either the rostra1 or the lateral portion of the telencephalon aggression was greatly suppressed, sexual activity was short in
duration, and parental care was rather extensive. However, after ablation
of the medial caudal portion-of the telencephalon these patterns appeared
to be reversed, with elevated aggression, continuous sex drive, and low
parental activity. Following medial lesions of the telencephalon, sticklebacks demonstrated rising aggressive behavior and depression of sex
drive, but otherwise they appeared to be normal. Lesions in the extreme
medial part of the caudal medial and dorsal medial areas of the telencephalon resulted in disinhibition of parental activity while aggression
and sex drive were normal (Segaar, 1965).
These data show that specific telencephalic lesions result in disruption of the balance of specific behavioral responses such as aggressive
behavior, sexual activity, and parental behavior in sticklebacks ( Segaar,
1965). The telencephalon appears to function as an organizer and
integrator of segments of innate (DNA contingent) behavior and maintains aggression, sexual activity, and parental behavior of fishes in the
proper balance to insure successful reproduction of the species.
F. Specific Sensory Deficits following Telencephalic Ablation
Color vision in goldfish has been studied using cardiac deceleration,
a conditioned autonomic response, as the measure of discrimination
( h4cCleary and Bernstein, 1959). After establishing the relative brightnesses of two pairs of red and green stimulus patches as perceived by
the fish, these same stimulus patches were used to determine whether a
subsequent discrimination by the fish was based on hue or brightness.
Stimulus generalization was used as a method of evaluating what aspect
of the stimulus was used by the fish in learning a given discrimination.
Goldfish were found to be capable of red-green hue discrimin a t' ion
under experimental conditions which ruled out the possibility that
brightness cues were being employed. The goldfish was also found to
be capable of stimulus generalization involving either hue or brightness
characteristics of the stimuli ( McClcary and Brrnstein, 1959).
Forebrain extirpation resulted in a selective suppression of the color
visual discrimination in goldfish. Immediately following complete bilateral telencephalic ablation, animals trained to red and green stimuli of