Gene P. Sackett

Prenatal psychological stress, dermatoglyphic asymmetry and pregnancy outcome in the pigtailed macaque (Macaca nemestrina).

The relationships between maternal psychosocial stress during pregnancy and asymmetry in dermal ridge count, gestation length, birth weight percentile and survival were examined in 68 pigtailed macaque offspring. Twenty-five pregnant females were stressed daily by capture from 30 through 130 days postconception; 43 control unstressed females were housed under conditions of minimal disturbance. The difference between total intercore dermal ridge counts between right and left hands of the offspring was used as a measure of the perturbed development that theoretically occurs in the presence of a prenatal stressor. Dermatoglyphic asymmetry was significantly higher in the stressed offspring than in the unstressed group (mean asymmetry = 7.3 +/- 2.8 and 5.4 +/- 2.5, respectively; t = 2.85, p less than 0.01). Although maternal stress alone was not related to differential gestation length, birth weight, or survival, high asymmetry (8-13 residual dermal ridges) was significantly associated with increased perinatal mortality.

Ultradian rhythms of solitary and social behavior in rhesus monkeys

Abstract Day-long observations were made on the social and nonsocial behaviors of five subadult to adult male monkeys. Social interaction between pairs of monkeys was found to occur as a cyclic process. In three of four pairs, the lengths of these cycles occurred as multiples of 45 min. Four nonsocial behaviors — ingestion, self-grooming, exploration and locomotion — were found to occur as cyclic processes when the monkeys were in either a social or a solitary setting. The lengths of these cycles again occurred as multiples of 45 min and in all four social pairings exploratory cycles of individual monkeys appeared to precede and be closely in phase with social interaction cycles.

Methylmercury effects on the social behavior of Macaca fascicularis infants

Observations of the social behavior of Macaca fascicularis exposed in utero to methylmercury (MeHg) and nonexposed control infants were performed as part of a study of the toxic, reproductive and developmental effects of maternal MeHg intake. Infants were tested twice weekly from 2 weeks to 8 months of age. Data were summarized into 6 categories of social behavior and 7 categories of nonsocial behavior. Analysis of the most prevalent behavior indicated that MeHg-exposed offspring exhibited a decrease in social play behavior and a concomitant increase in nonsocial passive behavior. The MeHg effect on social play behavior tended to decrease with age, while the group differences in nonsocial passive behavior tended to increase. The results indicate that maternal intake of MeHg during pregnancy can affect the social development of infant primates by suppressing social interactions and increasing nonsocial behavior.

Adrenocortical and behavioral reactions by differentially raised rhesus monkeys

Monkeys reared in social isolation or with an agemate were tested at 19 months for Cortisol responses following (1) ACTH injection and (2) initial experience in a novel playroom. Isolates had higher basal Cortisol, but did not differ from peer-raised monkeys in absolute Cortisol rise induced by ACTH or by the playroom experience. However, isolates did show more fear-disturbance-emotional behavior than did peers. The data suggest that basal Cortisol level may be a meaningful correlate of behavioral differences produced by differential rearing experiences in monkeys, but Cortisol rises induced by novel and complex stimulation are not correlated with these behavioral effects.

A FORTRAN program for lag sequential analysis of contingency and cyclicity in behavioral interaction data

One method for identifying contingency relationships in a sequence of observed behaviors studies occurrences of matching behaviors at successive event or time steps from a criterion event. This paper briefly summarizes the method and presents a computer program for generating lag conditional probabilities and associated measures for assessing statistical significance.

Digital data acquisition systems for observing behavior in laboratory and field settings

Electronic digital systems for recording behavior and for record keeping in hospital, clinical, laboratory, and field settings are now available from commercial sources. Behavioral events, occurring in real time, are coded by an observer who pushes buttons on an adding machine-type keyboard. Information is stored electronically on a cassette or other type of magnetic tape recorder. Tapes can be played, through appropriate interfaces, into a computer, keypunch, Teletype punch, or digital printer. Code frequencies, sequences, real-time durations, and modified frequency time-sample scores can be extracted from these records by hand or by-computer. This paper describes such systems, detailing methods of coding behavioral events and problems encountered in the use of digital observational systems.

Early experience effects on adaptive behavior: Theory revisited

Over 30 years ago, Sackett presented several ideas based on animal studies concerning effects of early experience on later adaptive behavior. The first idea proposed that rearing environment complexity produced individuals with a corresponding degree of psychological complexity. Enriched rearing produced individuals of high complexity who were willing to approach new and increasingly complex stimuli, thereby providing themselves with opportunities for learning and developing problem-solving strategies. Privation rearing produced individuals of low psychological complexity who avoided or withdrew from novel and complex stimuli, thereby depriving themselves of learning and problem-solving opportunities. The second idea concerned behavioral inhibition. It was proposed that a major developmental consequence of privation rearing was failure to inhibit high-probability responses that compete with those required for learning and adaptive problem solving when faced with new situations. A modern version of aspects of these ideas is contained in “executive function” theory. In this paper we review key animal literature that led to our theories, develop these theories in the light of newer findings, tie our ideas to those of executive function theory, and suggest how behavior by individuals with mental retardation may be related to privation rearing due to sensory-motor deficits regardless of any cognitive deficits. MRDD Research Reviews 1999; 5:30–40.

Behavioral measurement of temperament in male nursery-raised infant macaques and baboons

We define temperament as an individuals set of characteristic behavioral responses to novel or challenging stimuli. This study adapted a temperament scale used with rhesus macaques by Schneider and colleagues [American Journal of Primatology 25:137–155, 1991] for use with male pigtailed macaque (Macaca nemestrina, n = 7), longtailed macaque (M. Fascicularis, n = 3), and baboon infants (Papio cynocephalus anubis, n = 4). Subjects were evaluated twice weekly for the first 5 months of age during routine removal from their cages for weighing. Behavioral measures were based on the subjects interactions with a familiar human caretaker and included predominant state before capture, response to capture, contact latency, resistance to testers hold, degree of clinging, attention to environment, defecation/urination, consolability, facial expression, vocalizations, and irritability. Species differences indicated that baboons were more active than macaques in establishing or terminating contact with the tester. Temperament scores decreased over time for the variables Response to Capture and Contact Latency, indicating that as they grew older, subjects became less reactive and more bold in their interactions with the tester. Temperament scores changed slowly with age, with greater change occurring at younger ages. The retention of variability in reactivity between and within species may be advantageous for primates, reflecting the flexibility necessary to survive in a changing environment. Am. J. Primatol. 47:43–50, 1999.

Delayed Acquisition of Neonatal Reflexes in Newborn Primates Receiving A Thimerosal-Containing Hepatitis B Vaccine: Influence of Gestational Age and Birth Weight

This study examined whether acquisition of neonatal reflexes in newborn rhesus macaques was influenced by receipt of a single neonatal dose of hepatitis B vaccine containing the preservative thimerosal (Th). Hepatitis B vaccine containing a weight-adjusted Th dose was administered to male macaques within 24 h of birth (n = 13). Unexposed animals received saline placebo (n = 4) or no injection (n = 3). Infants were tested daily for acquisition of nine survival, motor, and sensorimotor reflexes. In exposed animals there was a significant delay in the acquisition of root, snout, and suck reflexes, compared with unexposed animals. No neonatal responses were significantly delayed in unexposed animals. Gestational age (GA) and birth weight (BW) were not significantly correlated. Cox regression models were used to evaluate main effects and interactions of exposure with BW and GA as independent predictors and time-invariant covariates. Significant main effects remained for exposure on root and suck when controlling for GA and BW, such that exposed animals were relatively delayed in time-to-criterion. Interaction models indicated there were various interactions between exposure, GA, and BW and that inclusion of the relevant interaction terms significantly improved model fit. This, in turn, indicated that lower BW and/or lower GA exacerbated the adverse effects following vaccine exposure. This primate model provides a possible means of assessing adverse neurodevelopmental outcomes from neonatal Th-containing hepatitis B vaccine exposure, particularly in infants of lower GA or BW. The mechanisms underlying these effects and the requirements for Th requires further study.

The Effects of Rearing Experiences: The Early Years

Perhaps the most basic tenet of development is that behavior is subject to the multiple influences of genes and environments. In fact, it is the dynamic, temporal interaction between genetic and environmental factors that yields different developmental outcomes. Few would disagree with this view today. However, in the middle of the 20th century, when experimental rearing paradigms were first developed and studied in rhesus macaques, the view was different. Behavior patterns were construed as being controlled by either genes or the environment. Ethologists studied species-typical behaviors called fixed action patterns— “fixed” because they were thought to be uninfluenced by experience. In a similar manner, psychologists studied learned behavior that was thought not to have any genetic basis. This dichotomous view permeated the science of the time. Some took on the task of “proving” that specific behavior patterns were innate and developing the methodology to do so (Lorenz, 1950); others attempted to show that organisms were essentially molded by their experiences (Skinner, 1975). There were other voices arguing that all behavior was under both genetic and environmental control (Lehrman, 1970; Schneirla, 1957), but this interactionist notion had not yet taken firm hold. It is important to remember that the early studies of rearing in nonhuman primates took place in this context.