Averaged cortical evoked responses in man to repetitive informationally complex pictorial stimuli, as opposed to other visual stimulation, were obtained from scalp electroencephalographic (EEG) recordings. The method used involved the projection of lantern slides. Included were three different categories (indifferent scenic, repulsive medical, and nude female photographs) assumed to evoke, respectively, neutral, negative, and positive reactions in the normal young male subjects. In all subjects, recordings from occipital or occipitoparietal scalp leads consistently resulted in evoked response patterns to pictorial slides measurably differing from responses to these same slides made non‐associational through defocusing, or to blank light flashes. Responses to pictorial stimuli were also different than those to motivated observation of projected words, colors, or geometric patterns. The evoked responses to the three different categories of pictorial stimuli also showed significant differences. These differences were not as marked and were clearly replicable only for some subjects.

This study examined sexual and other social behavior in relation to menstrual cycle phase in four mixed-sex social groups of Cebus apella. Groups consisted of two adult males and either six or nine adult females. Menstrual cycles of high (rank 1-2) and low (rank 3-7) dominance-rank females from each group were monitored via vaginal swabs, and correlated with data collected from ongoing behavioral observations. Only cycles bounded by positive detection of menstrual blood were included in this analysis (n = 15 females, 182 cycles; mean ? s.d., cycle length = 20.8 2 1.2 days). Rates of copulation and female solicitation of males varied significantly with cycle phase, with highest rates a t midcycle. While total rates of solicitation and copulation did not vary with female dominance rank, copulation rates with the dominant male were significantly greater for high ranking females than for low ranking ones. Variance observed in affiliative and agonistic behaviors, including those with males, was attributable to female rank rather than cycle phase. Females and males were also observed attempting to interfere with copulations of lower ranking same-sex individuals. Although further study, particularly of wild populations, is needed, these results indicate that female-female reproductive competition should be included as a component of the capuchin breeding system. As in other primate species, both social and hormone-related factors influence the sexual behavior of Cebus apella.

No abstract

Phencyclidine (PCP) and other NMDA receptor antagonists such as ketamine induce psychotic symptoms that are difficult to reverse with current medications and which closely resemble those of schizophrenia. This study investigated the behavioral effects of continuous PCP administration in six socially-housed Cebus apella monkeys. Chronic treatment was associated with a sustained decrease in stereotyped locomotion (pacing) and a sustained increase in scanning behavior. Treatment was also associated with a modest decrease in self- and environment-directed behavior and goal-directed locomotion and an increase in affiliative behavior at lower doses. Four animals had one or more episodes of extreme motoric and physiological responses precipitated by stressful events. The results indicate that behavioral effects of chronic PCP in primates differ from those seen following acute treatments and represent an appropriate model system for new antipsychotic drug development.

To examine whether or not prolonged exposure to a depot neuroleptic has either residual or "tardive pathological" effects on normal behavior, 38 Cebus apella monkeys were observed daily for 108 weeks. The issue of stress influencing such effects was also addressed. During weeks 25-48 half of the monkeys received 0.22 mg/kg fluphenazine decanoate, IM, every 3 weeks, with the dose increased to 0.33 mg/kg during weeks 49-72. Behavioral measures were combined to form composite behavioral variables which quantify four major aspects of behavior: self- and environment-directed behavior, affiliation, aggression, and normal locomotor activity. Mean plasma fluphenazine levels at 48 h post-injection were 0.13 (+/- 0.03) ng/ml for injections 3-8 and 0.24 (+/- 0.07) ng/ml for injections 11-16. The pre-study null hypothesis that the four major aspects of behavior would not be adversely affected by this treatment during the drug-discontinuation phase of the study (weeks 73-108) was not statistically negated. There were highly significant decreases in self- and environment-directed behaviors and affiliation during the treatment periods, implying that treatment may contribute to the negative symptoms of treated schizophrenics. Stress reduced the above effects. Aggression showed some increase during early drug discontinuation, accentuated by stress. Recovery of normal (baseline) behavioral scores began by week 7 after the last treatment. Mild (bucco-lingual) tardive dyskinesias persisted in 30% of the animals for a prolonged time.