Michael W. Andrews

Adverse early experiences affect noradrenergic and serotonergic functioning in adult primates.

It has been proposed that certain adverse early experiences may play a role in determining subsequent susceptibility to adult anxiety and affective disorders and this relationship may be the result of altered neurodevelopment of the noradrenergic and/or serotonergic systems. In this study of nonhuman primates, the predictability of foraging requirements for mothers during an early period of their infants lives was manipulated. When the offspring were young adults, these early manipulations were related to differences in behavioral response to acute administration of two putative anxiety-provoking agents: the noradrenergic probe, yohimbine, and the serotonergic probe, mCPP. These long-term effects of the developmental environment on subsequent pharmacological responsivity suggest that both neuronal systems may be permanently altered by early experiential factors.

Live-Social-Video Reward Maintains Joystick Task Performance in Bonnet Macaques

A number of studies have now indicated that monkeys of several species will perform hundreds of food-rewarded joystick tasks on a daily basis. Our goal in this study was to identify the level of joystick task performance that could be maintained by 10 sec. of live, color video of a conspecific social group contingent upon the completion of a joystick task. The subjects were five individually housed bonnet macaques that were highly experienced on joystick tasks. Performance with social-video reward was compared to that maintained by a 190-mg banana-flavored pellet reward and to a nonreward condition. Comparable levels of task activity were maintained by both video and pellet reward, whereas task activity nearly ceased in the absence of reward. Four of the five monkeys increased their levels of task activity between the first and second weeks of social-video reward.

Assessment of attachment in differentially reared infant monkeys (Macaca radiata): Response to separation and a novel environment.

To assess the developmental consequences of rearing environments for 12 infant bonnet macaques (Macaca radiata), infants from 2 environments, either low foraging demand (LFD) or variable foraging demand (VFD) for their mothers, were observed under 2 test conditions after the completion of the differential rearing treatment. One of the test conditions involved introduction of the rearing cohorts to a novel room; this was done in two series of four 1-hr sessions, a series before and a series after completion of the 2nd test condition. The 2nd test condition involved a 20.5-hr removal of each mother from the rearing cohort; this was repeated once a week for 3 weeks. The results of the novel room tests effectively differentiated rearing treatments in this study and suggested treatment group differences in attachment security. In contrast, the maternal separations failed to differentiate rearing treatments.

Video-task paradigm extended to Saimiri

In the “video-task paradigm” a subject manipulates a joy-stick to move a cursor into an experimenter-defined target area on a computer monitor, generally receiving a food reward upon completion of the task. Despite the spatial separation of the joy-stick, monitor, and location of reward delivery, the video-task paradigm has been successfully implemented with several macaque species and with chimpanzees. Preliminary attempts to implement the paradigm with squirrel monkeys, however, were not successful. This report describes successful performance by a squirrel monkey in the paradigm. After learning to move the cursor to contact a small target randomly appearing at four screen locations, the monkey was readily able to move the cursor to contact a moving target in novel locations on the monitor screen.

Acquisition and long-term patterning of joystick selection of food-pellet vs social-video reward by Bonnet Macaques

Five individually housed, adult male bonnet macaques ( Macaca radiata ) that were highly experienced in single-target joystick tasks were trained to discriminate targets associated with food-pellet and live-social-video rewards; the social video afforded viewing of a social group of bonnet macaques. Most subjects more rapidly acquired the discrimination for their preferred reward. Following discrimination training, the remaining three subjects were given 34 weeks with a simultaneous choice between food-pellet and social-video; the subjects selected a reward by simply using a joystick to direct a cursor to contact the target associated with that reward. Despite some change over time, both types of reward remained effective for the extended period. Different daily patterns of responding for the two rewards were identified.

Selection of food sites by Callicebus moloch and Saimiri sciureus under spatially and temporally varying food distribution

Abstract The choice behavior of eight titi monkeys ( Callicebus moloch ) and eight squirrel monkeys ( Saimiri sciureus ) was examined in an eight-arm maze under varying conditions of spatial and temporal food abundance at the goals. When every choice of any of the eight goals resulted in the same food reward, neither species exhibited a tendency to avoid goals previously selected in a daily session. Callicebus , however, did exhibit a spatial bias under this condition. Both species exhibited the ability to avoid previously selected goals when returns to a goal within a daily session were not rewarded. Under conditions in which the goals differed in food abundance, both species tended to select goals so as to maximize the amount of food obtained. When the food abundance at each goal changed abruptly, neither species accommodated rapidly to the changes. Only transitions in abundance of large magnitude significantly influenced goal preferences.

RELATIVE EFFICACY OF VIDEO VERSUS FOOD-PELLET REWARD OF JOYSTICK TASKS

We suggest that the data reported by Washburn and Hopkins in their comment on our demonstration of the efficacy of live-video reward of joystick tasks supports, rather than impeaches, our earlier findings.

Environmental structure influences use of multiple video-task devices by socially housed pigtail macaques

The video-task paradigm has been suggested as a means of providing enrichment for laboratory primates. The purpose of this study was to investigate the effect of providing multiple devices to socially housed pigtail macaques. Using different cage locations, the subjects were tested with conditions of access to a single device and with access to three identical devices. Differential preference among locations was strongly evident, but only when multiple devices were simultaneously accessible. Although a single device was never used to its theoretical maximum potential, overall device utilization was significantly higher with multiple devices available. Provision of a perch that equalized the substrate at all locations diminished, but did not eliminate, differential preference among locations.

Effects of oral yohimbine on the performance of a perceptual-motor task in nonhuman primates

Abstract Ethical and practical constraints limit the range of studies that can be performed on patients with anxiety disorders. A nonhuman primate model allows for a variety of experimental manipulations that cannot be attempted in humans. In this paper, we report on the further development of a nonhuman primate model of pathological anxiety, which we have labeled acute endogenous distress (AED). Bonnet macaques were challenged with the oral administration of the alpha-2 antagonist, yohimbine. Whereas our previous work has documented the behavioral response to yohimbine provocation, in this paper we report the drugs effects on the monkeys performance on a novel video computer device that presents well defined perceptual- motor tasks of varying difficulty. Under yohimbine challenge, animals virtually stopped initiating a complex task requiring sustained attention and perceptual-motor control; however, they showed no decrease in initiating and performing an easy task under the same pharmacological challenge, thus demonstrating that the effect was cognitive rather than motor in nature.

NURSERY PARADIGM ENHANCES MOTOR ENGAGEMENT OF A NOVEL ENVIRONMENT BY INFANTS OF MOTHERS WHO HAD A DEMANDING TASK

Two groups of bonnet macaque (Macaca radiata) mother-infant dyads were exposed to 12 wk. of a variable foraging demand paradigm for the mothers beginning when the infants were approximately 18 weeks of age. For the nursery group, infants were required to remain in a nursery within the mothers living area during the entire treatment period. Testing of the dyads of both groups in a novel room subsequent to the differential rearing experience showed that only the infants required to remain within the nursery exhibited an increase in motor engagement of the novel environment over the first hour of exposure, possibly reflecting greater security of attachment in these nursery infants.