Infrahuman Primates Research Articles

Memory Strength and Repetition Suppression: Multimodal Imaging of Medial Temporal Cortical Contributions to Recognition

Declarative memory permits an organism to recognize stimuli that have been previously encountered, discriminating them from those that are novel. One basis for recognition is item memory strength, which may support the perception of stimulus familiarity. Though the medial temporal lobes are known to be critical for declarative memory, at present the neural mechanisms supporting perceived differences in memory strength remain poorly specified. Here, functional MRI (fMRI) and anatomically constrained magnetoencephalography (MEG) indexed correlates of graded memory strength in the human brain, focusing on medial temporal cortex. fMRI revealed a decrease in medial temporal cortical activation that tracked parametric levels of perceived memory strength. Anatomically constrained MEG current estimates revealed that strength-dependent signal reductions onset within 150-300 ms. Memory strength appears to be rapidly signaled by medial temporal cortex through repetition suppression (activation reductions), providing a basis for the subjective perception of stimulus familiarity or novelty.

Emetine ditartrate: a possible lead for emergency contraception

Interception of pregnancy in its initial stage is an attractive and viable approach to contraception. A chemical agent, taken within the first few days of missed menses, intercepts the conception, which is expelled with menstrual flow. The main targets of such agents are the uterus, blastocyst and the growing trophoblasts, whose nutritional requirement is inhibited. Our previous work has identified several nonsteroidal chemical entities as pregnancy interceptives in rodents and infrahuman primates. However, none reached clinical stage due to their ineffectiveness by oral route. Nevertheless, parallel to these rationally designed synthetic compounds, a program was ongoing to identify natural product(s) that can be used as interceptives. We are reporting for the first time the detailed profile of emetine ditartrate, a compound whose pregnancy interceptive efficacy has been studied in mouse, rat, hamster, guinea pig and rabbit by oral and intravaginal routes of administration. By the oral route, the compound caused 100% resorption of the fetuses in rat, hamster and guinea pig at 6.0, 5.0 and 3.0 mg/kg, respectively, on administration during peri- and early postimplantation periods of pregnancy (depending upon the day of implantation in each species). By intravaginal route, the compound was administered once in the form of a vaginal pessary on the day of implantation in respective species; interception of pregnancy was not achieved completely in rat and hamster at doses four to five times the oral dose in multi-day schedule. However, in guinea pig and rabbit it was fully effective at 7.0 and 70.0 mg/animal, respectively. The compound was devoid of estrogenic, antiestrogenic and progestational activity but possessed mild antiprogestational activity at the high dose in vivo. In in vitro assay, however, it did not show any significant binding to estrogen and progesterone receptors. The mode of action of the compound was found to be mainly on the uterus and early embryos around implantation, possibly on the trophoblasts and endometrial cells at the attachment site. The absence of 100% efficacy in rat and hamster by intravaginal route, but not by oral route, is possibly due to poor absorption of the compound through the vagina in these species. The guinea pig and rabbit, therefore, seem the better species for evaluating the efficacy of the compound administered by the vaginal route.

Contributions to the history of psychology: XCIX. Experimental study of infrahuman primate sexual behaviors: James Harlan Elder.

Prior to the 1930s, designs of research into sexual behavior of infrahuman primates were not comparable; conclusions about physiological and nonphysiological factors in receptivity and mating were confounded by species studied, living and testing conditions, and precaptivity history. Clearly there was need for comprehensive and controlled studies of infrahuman primate sexual behavior. In response to the controversy about biological bases of receptivity and mating, James Harlan Elder, in collaboration with Robert M. Yerkes, designed the first truly comprehensive study of factors influencing sexual behavior of chimpanzees. At that time, other persons interested in this problem were employing experimental methods, but Elder's and Yerkes' program most directly addressed the problems confounding prior study and their work served as a model of experimental research into factors affecting receptivity and mating of infrahuman primates.

6-Hydroxydopamine lesions of the prefrontal cortex in monkeys enhance performance on an analog of the Wisconsin Card Sort Test: possible interactions with subcortical dopamine

The effects of 6-hydroxydopamine lesions of the prefrontal cortex in monkeys were investigated on two cognitive tests of prefrontal function, spatial delayed response, and attentional set shifting. The latter test provided a componential analysis of the Wisconsin Card Sort Test, a commonly used clinical test of frontal lobe function in man. Acquisition of a visual compound discrimination requiring a shift of attention from one dimension to another (extradimensional shift), for example, shapes to lines, was significantly improved. This enhancement was behaviorally specific in that there were no effects on acquisition of a discrimination that required the continued maintenance of an attentional set toward one particular dimension (intradimensional shift), nor any effects on a series of visual or spatial discrimination reversals that involved the repeated shifting of responding between two exemplars from the same dimension. In contrast, spatial delayed response performance was impaired, in agreement with previous results. Neurochemical measures showed a marked depletion of dopamine limited to the prefrontal cortex and a smaller loss of prefrontal noradrenaline. This was accompanied by a long-term adaptive change in the striatum such that extracellular dopamine in the caudate nucleus, as measured by in vivo microdialysis, was elevated in response to potassium stimulation as long as 18 months postsurgery. It is proposed that attentional set shifting is mediated by a balanced interaction between prefrontal and striatal dopamine, and that elevated dopamine contributes to the improvement in attentional set-shifting ability. This interpretation is consistent with the impairment in attentional set-shifting ability observed in patients with Parkinson's disease or with damage to the frontal lobes using the same test as used here for infrahuman primates.

The roles of imagery, language, and metamemory in cross-modal transfer in children.

The relative strengths of association of imagery, language, and metamemory to cross-modal transfer were evaluated in 5-year-olds and 7-year-olds. Children were administered either tactual-visual or visual-tactual cross-modal transfer tasks, as well as two visual imagery tasks (spatial recall and mental rotation), two language competence tasks (vocabulary and word usage), metamemory questions, and a general intelligence task. With intelligence and handedness controlled, only visual imagery related significantly to cross-modal transfer. These findings suggest that mental imagery, as opposed to language competence or metamemory, is a principal component of cross-modal transfer, and they are consistent with the observation that preverbal human infants and infrahuman primates exhibit cross-modal transfer.

Buspirone attenuates volitional alcohol intake in the chronically drinking monkey

Four macaque monkeys which showed excessive preference for ethyl alcohol solutions in a self-selection paradigm were used as subjects. Earlier these animals had been given intracerebroventricular (ICV) injections of human cerebrospinal fluid, which produced pharmacologically significant effects on the animals' alcohol consumption. The purpose of the present investigation was to determine whether the parenteral administration of a new anxiolytic compound, buspirone, would alter the pattern of alcohol drinking already established in the monkey. Initially the maximally selected concentration of alcohol of 12% was determined on the basis of a standard ad lib alcohol-water preference screen. Each monkey was offered 12% alcohol and water for a basal pre-injection period of 4 days. Then, on each of the next three days, either the saline control vehicle or buspirone, 1.25, 5.0 or 20.0 mg/kg, was injected intramuscularly at 930 and 1630 hours. On these days, behavioral observations were recorded before and after buspirone's administration in order to evaluate the latency as well as recovery from the drug's effect. Subsequently, a four-day post-injection, 12% alcohol-water test was conducted. Although the saline control and 1.25 mg/kg dose of buspirone were without effect on alcohol intake, both the 5.0 and 20.0 mg/kg doses of buspirone attenuated significantly the consumption of alcohol by the monkeys. This reduction in terms of absolute g/kg as well as the proportion of alcohol to water ingested was approximately 30–60% of baseline intakes. Following buspirone treatment, the amount of alcohol consumed returned essentially to previously high levels. These results suggest that a neurohumoral substrate having an anxiety-like component could underlie, at least partially, the abnormal ingestion of alcohol in the infra-human primate.

Antagonism by naltrexone of voluntary alcohol selection in the chronically drinking macaque monkey

An opiate receptor antagonist can reduce excessive alcohol drinking in the rat previously given intracerebroventricular (ICV) infusions of a tetrahydroisoquinoline. Recently, it was found that cerebrospinal fluid (CSF) obtained from volunteers or human patients and subsequently injected ICV in macaque monkeys markedly alters the voluntary consumption of ethyl alcohol in certain of these primates. The purpose of the present study was to determine whether an opioid antagonist would affect the pattern of alcohol intake in selected monkeys which drank excessive amounts of alcohol. Initially, the preferred concentration of alcohol was determined individually for each monkey which consistently drank from 3.0–6.0 g/kg alcohol per day. Subsequently, the single concentration, which ranged from 5–15%, was offered together with water during three consecutive periods as follows: (1) 4-day control baseline period; (2) a 3-day interval during which a saline control vehicle or 0.6 or 1.2 mg/kg naltrexone was administered subcutaneously at 0900 and 1700 hours; and (3) a final 4-day post-injection period during which the alcohol-water preference test was continued. The results showed that both doses of naltrexone significantly attenuated voluntary alcohol drinking up to 60% of the baseline intake during the 3 days of its administration. In two monkeys, alcohol drinking continued to be suppressed up to 50% of basal intake during all or a part of the 4-day post-naltrexone interval. These findings suggest that an opiate receptor mechanism in the brain could be partially involved in the action of the chemical constituents of the human's CSF which serve to induce an abnormally high intake of alcohol in the infra-human primate.

Sexual cyclicity and concealed ovulation

The disappearance in human evolution of mid-cycle estrus, present in infrahuman primates, is considered in relation to studies of periodicity of sexual desire and activity in the human female. Evaluation of investigations suggests the presence of a bimodal pattern of elevated sexual arousability, with peaks in the premenstrual phase and around ovulation at mid-cycle.

The distribution of cholecystokinin and vasoactive intestinal peptide in rhesus monkey brain as determined by radioimmunoassay

The concentration of cholecystokinin (CCK) and vasoactive intestinal peptide (VIP) in dissected cortical and subcortical areas of four rhesus monkeys' brains was determined by radioimmunoassay (RIA). Cerebral cortical samples from one human brain are included for comparison. Preliminary data from two baboon brains are described. The results are similar to previous studies on rat (1–7), human (7–12), porcine (12,13), bovine (3) and guinea pig brains (14) and indicate that: 1) both CCK and VIP are widely distributed in cortical and subcortical areas in these species, 2) CCK is generally more abundant than VIP in primate brain, and 3) the distribution of CCK and VIP in the rat brain parallel those in infrahuman primate and human brain.

Therapeutic sex drive reduction.

Sex drive reducing therapies are employed in those cases of anomalous erotic preferences in which the patient's sexual behaviour is dangerous (certain forms of sadism, or a preference for forcing intercourse or similar interaction) or while not really dangerous, is utterly unacceptable to the community (pedophilia and pedohebephilia) or is an embarrassment to the patient himself (exhibitionism). Three sex drive reducing therapies are in use, all designed for male patients, (1) pharmacological reduction of circulating testosterone, (2) orchidectomy, (3) deletion of certain brain structures by stereotaxic surgery. The main indication for pharmacological sex drive reduction is exhibitionism but here it should be used only temporarily, as a first emergency measure, and after that only intermittently, during periods when the patient can not manage his urges by techniques he should be taught by a behaviour therapist. In cases of unmanageable and dangerous sadism, orchidectomy is the method of choice--and the same would appear to be true for particular cases of pedohebephilia. Brain surgery in this realm is not yet based on sufficient knowledge and should be thoroughly studied on infrahuman primates, before use with humans could be seriously considered.

Phylogenetic precursors of psychiatric illness: A theoretical inquiry

A widely-held assumption in psychiatry is that an illness such as schizophrenia is found widely distributed among cultures of the world. Indeed, except for exponents of the viral etiology, most would probably hold that schizophrenia was prevalent in earlier recorded and unrecorded historical epochs. 1 If all human groups show and have shown instances of schizophrenia, it is appropriate to inquire if this prevalence extends into the evolutionary past of homo sapiens. Biologic psychiatrists have found useful the notion of animal models of psychiatric disorders such as schizophrenia (and also depression). 2 Yet the possibility that schizophrenia may be found under natural field conditions in humanoid and infrahuman primates is infrequently considered in sociobiology and primatology. Many issues are raised when shifting from the laboratory where animal models are literally manufactured to field conditions where instances of disease and illness might conceivably occur “naturally”. In this paper, we discuss this general topic from a theoretical standpoint. We attempt to show that the possibility of infrahuman primates showing schizophrenia raises basic questions about brain-behavior relations and also related questions about the functioning of social cultural systems. The aim of the paper is to clarify the position of psychiatric inquiry in a general biologic frame of reference.

Temporal relationships of estrogen, progesterone, and luteinizing hormone levels to ovulation in women and infrahuman primates

These studies were undertaken to ascertain the interval between the estrogen and LH peaks and ovulation in women, rhesus monkeys, and baboons. Estrogen, progesterone, and LH were measured by RIA. Ovulation was documented by visual examination of the ovaries, histology of the corpora lutea, and recovery of ova. The data for human subjects was based on a group of 23 normal women scheduled for surgical sterilization. Blood was drawn daily between 8:30 and 10:30 p.m. beginning on day 10 of the cycle. Surgery was performed 1 to 5 days after the LH peak. The hormonal findings were correlated with the histology of the corpus luteum. The mean interval from the estrogen peak to ovulation was 34 hours, the interval from the estrogen peak to the LH peak was 24 hours, and that from the LH peak to ovulation was 9 hours. In 46 rhesus monkey cycles and in 53 baboon cycles diagnostic serial laparoscopic examinations were initiated following the estrogen peak and repeated every 24 hours until ovulation was confirmed. The mean interval between the estrogen peak and ovulation was 34 hours in the monkey and 41 hours in the baboon. The intervals from the estrogen peaks to the LH peaks were 12 hours in the monkey and 23 hours in the baboon. The intervals from LH peak to ovulation were 22 hours in the monkey and 18 hours in the baboon. Plasma progesterone levels were significantly increased prior to the LH peak in all three species.

Auditory perception and speech evolution.

Human speech perception seems to involve the ability to recognize groupings of speech sounds rather than component phonemes, and to distinguish between permuted orders of items within sequences as holistic entities. Humans can use this Holistic Pattern Recognition (HPR) not only with speech and music, but also with sequences of arbitrarily selected sounds after very little practice. Infrahuman primates, cats, chinchillas, and birds also seem to employ HPR with auditory sequences. Further, there is recent evidence that animals unable to produce speech sounds can nevertheless discriminate between closely related phonemes. Thus, it appears that human speech perception employs prelinguistic abilities shared with other animals to distinguish between phonemic groupings. Of course, use of speech for communication also requires establishment of phonemic groupings as symbols, and sequential arrangement of these symbols, by rule, to convey the desired message. Identification of Components and their Order (ICO) for auditory sequences is limited to humans. ICO involves verbal categorization and storage of the names for successive auditory items as they appear, followed by retrieval or the names in the order stored. Thus, direct identification of the order of sounds within auditory sequences rests upon verbal ability, which provides an explanation for the difficulty that aphasics have in identifying order within nonverbal sequences. Much confusion in the literature on auditory sequence perception seems to have resulted from a failure to differentiate between HPR and ICO.

Glancing at Others in Preschool Children in Relation to Dominance

Previous research has shown a relationship between glancing and dominance in a variety of primate species. In these species, subordinate animals glance more frequently and dominant animals are more frequently the object of glances. In the present study, 30 children in two nursery school classes were observed to determine dominance relationships. The dominance hierarchies obtained by observation were highly correlated with rankings of relative dominance by the classroom teachers. The children were then observed for frequency of glancing along with the object of each glance. It was found that the relationship between glancing and dominance for these preschool children was highly similar to the relationships reported for infrahuman primates.

Acculturation as a Factor in TraditionalVersusAtraditional two-Trial Learning Sets

Summary The present study hypothesized that acculturation of human Ss affects learning performance of such Ss, but doesn't affect that of infrahuman primates. If this is so, then differences as a function of age should be manifest in human Ss. Ss were 24 college students, aged 19; 24 parochial school students, aged 12; and 24 such students, aged 7. Sex representation was equal in each group. The Ss, using the median test, showed a significant decrease in errors as a function of age on two-trial response perseveration learning set to reinforced cues combined with two-trial response shift learning set to reinforced cues (x = 6.0000, df = 2, p & .05). No significant differences as a function of age were manifest on two-trial response perseveration learning set to nonreinforced cues combined with two-trial response shift learning set to nonreinforced cues (X = 4.6664, df = 2, p > :05). It was concluded that such findings may be attributed to acculturation.

Species continuity in the thermoregulatory responses of the pigtailed macaque to monoamines injected into the hypothalamus

1. 1. In the unanaesthetized pigtailed monkey ( Macaca nemestrina) in which body temperature was monitored, 5-hydroxytryptamine (5-HT) and norepinephrine were micro-injected into the hypothalamus. 2. 2. 5-HT in dose of 2·5–10·0 μg caused a dose-dependent rise in temperature. Conversely, norepinephrine in a similar range of doses produced a fall in temperature. 3. 3. The region of maximum responsiveness to the two monoamines was the thermosensitive zone in the interior hypothalamus. 4. 4. These results provide additional support for the modulatory role of the monoamines in thermoregulation in the infra-human primate.

Can linguistic competence be dissociated from natural language functions?

THE preservation of non-verbal intellective functions in spite of severe disruption of natural language has been well documented by studies of aphasia1. But are the cognitive functions specific to normal verbal communication also preserved in the absence of language? In addition to its theoretical significance, this question has practical importance with respect to both infra-human primates and severe aphasics2. These groups cannot use natural language because of the destruction or apparent absence of crucial cortical zones of the brain and effective communication may depend on their mastering an alternative symbol system which captures relevant cognitive properties of natural language. A crucial test of the hypothesised dissociation between natural language and its cognitive prerequisites is whether aphasic subjects can use arbitrarily designed symbols to represent elements of experience (events, properties, actions and so on); encode meaningful relationships in terms of the configurational properties, or syntax, of the symbol sequence; and have the capacity to encode such relationships in alternative syntactic forms3,4.

Volatile fatty acids, "copulins", in human vaginal secretions.

(1) In a double-blind study using a new tampon method, 682 samples of vaginal secretions were collected from 50 healthy young women attending a university. (2) Samples were analyzed by gas chromatography for the volatile fatty acids (C2-C6) that have sex-attractant properties in infra-human primates. (3) All subjects produced some acids but acetic predominated; however, 30% of women provided samples containing more than 10 μg of other acids in addition to acetic, and these women formed a sub-group termed ‘producers’. (4) The content of volatile acids increased significantly during the first half of the cycle and declined during the second half of the cycle. (5) Increases in propanoic, methylpropanoic, butanoic, methylbutanoic and methylpentanoic acids contributed especially to the increased content during the first half of the cycle. (6) Women taking oral contraceptives had a lower overall content of acids in their vaginal secretions, and the mid-cycle increase was absent. (7) The mid-cycle increase was particularly well-marked in women ‘producers’. (8) The biosynthesis of the acids is discussed.

Learning Mechanisms in Two-Trial Learning Sets by College Students

Summary Undergraduate college students were tested to an arbitrary learning criterion on two-trial learning set formations. Results showed significantly easier acquisition of two-trial response-perseveration learning set to reinforced cues and two-trial response-shift learning set to nonreinforced cues than for two-trial response-perseveration learning set to nonreinforced cues and two-trial response-shift learning set to reinforced cues. Additional results showed that the subjects, after learning, had learned to approach or to avoid either reinforced or nonreinforced stimuli actually manipulated on the initial trials of each problem. These results were compared to the results of similar tests using infrahuman primates as subjects.

An Observational Technique for Preschool Children

Summary A method for direct observational study of early peer-social and objectdirect behavior for human subjects was designed to be articulated with techniques widely used in studies of social behavior in infrahuman primates. Occurrence of behavior fitting the definitions of each of six categories of object behavior and nine categories of social behavior is noted once during each 15-second interval. The number of recorded intervals in a 15-minute session provides the basic scoring unit. Observer reliabilities were estimated from paired data and four observers. Thirty-eight Negro and white children ages three through five years were observed in three child play groups. Median reliabilities of .95 (range .63 to .98) and .81 (range .69 to .94) were obtained for object and social behavior categories respectively.