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.

Automated recording of individual performance and hand preference during joystick-task acquisition in group-living bonnet macaques (Macaca radiata).

A microchip that provided a unique identification number was injected into each forearm of all 8 members of a bonnet macaque (Macaca radiata) social group. The group was then given computer-controlled joystick tasks of increasing difficulty. The identification number of the arm used on each trial was input into the computer and used to determine individual performance and hand preference in more than 23,000 trials. Three subjects reversed hand preference as task difficulty was increased over time. All subjects exhibited nearly exclusive use of a single hand on the most difficult task; 6 used the right hand, and 2 used the left. Daily patterns of joystick activity for the group members differed somewhat from that of our individually housed monkeys.

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.

Identification of speeded and slowed familiar melodies by younger, middle-aged, and older musicians and nonmusicians.

There is a range of tempos within which listeners can identify familiar tunes (around 0.8 to 6.0 notes/s). Faster and slower tunes are difficult to identify. The authors assessed fast and slow melody-identification thresholds for 80 listeners ages 17-79 years with expertise varying from musically untrained to professional. On fast-to-slow (FS) trials the tune started at a very fast tempo and slowed until the listener identified it. Slow-to-fast (SF) trials started slow and accelerated. Tunes either retained their natural rhythms or were stylized isochronous versions. Increased expertise led to better performance for both FS and SF thresholds (r = .45). Performance declined uniformly across the 62-year age range in the FS condition (r = .27). SF performance was unaffected by age. Although early encoding processes may slow with age, expertise has a greater effect. Musical expertise involves perceptual learning with melodies at a wide range of tempos.

Influences of environmental demand on maternal behavior and infant development.

Research has shown that in conjunction with genetic factors, significant aspects of non-human primate development are influenced by the infant's physical and social environment. In addition to the direct impact of the environment on the infant, the infant's attachment relationship with the mother is seen as the primary mediating factor in shaping these influences. When the mother is able to cope with environmental demands, as a reflection of her responsivity to her infant's needs, she may prepare infants for periodic interruptions in her attention, ameliorate distress during disruptive periods and, most importantly, compensate for these disruptions with enhanced attention to her infant once they are ended. Our recent work shows that when the mother's survival requirements increase, and her coping capacities are exceeded, both short- and long-term deleterious effects on her developing offspring may emerge. Particularly when confronted with an unpredictable environment, mothers are less able to maintain effective, stress-buffering, maternal-coping mechanisms which can preserve a stable attachment relationship and permit normal infant development. When these coping mechanisms are insufficient, infants may show manifest disturbances, such as depression, during development or reveal more latent disturbances, such as reduced sociability and timidity, when psychologically challenged, even as young adults. Evidence now suggests that these long-term effects may, at least in part, be the product of altered neurodevelopment of the serotonergic and noradrenergic systems.

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.

Emergence of handedness in bonnet macaques (Macaca Radiata) on a task they were equally capable of performing with the left or right hand.

Seven bonnet macaques that exhibited no asymmetry in the accuracy or latency with which the right and left hands used a joystick to direct a cursor to a moving target nevertheless came to exhibit a strong hand preference in performing the task when allowed to use either hand.

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.

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.

Ultrasound of the spleen.

Ultrasound (US) is a very useful means of noninvasively examining the spleen. Imaging is generally achieved via an intercostal approach using gray scale US supplemented by color flow to assess vasculature. Normal spleen appears uniform with vessels radiating and converging at the hilum. US readily identifies accessory spleens, a common congenital variation. Splenomegaly can be identified by US, however, it is not useful in differentiating the many causes of an enlarged spleen. Focal splenic masses are identified as cystic or solid by US, and features such as calcification, wall thickening, internal debris, and gas may be demonstrated in cystic type masses. Granulomatous calcification may be seen with US and cavernous hemangiomata typically have a characteristic US appearance. US can demonstrate typical features of splenic infarction. Splenic injury can be detected with US, however, whether US is the most appropriate first line investigation for suspected splenic injury is yet to be determined. It is a very useful follow-up modality for monitoring splenic injuries detected by either US or computed tomography which are treated conservatively.

The development of affiliative and agonistic social patterns in differentially reared monkeys.

Bonnet macaques that had been reared from 3 to 6 months of age in experimental environments that appeared to adversely affect their ability to separate from mother to explore a novel physical environment in dyadic assessments shortly after the rearing experience were tested during late adolescence, an average of 2.5 years later, under conditions of increasing unfamiliarity and complexity of the social milieu. 6 monkeys, the low-foraging-demand (LFD) group, were reared by mothers having constant easy access to food during the experimental rearing period. Another 6 monkeys, the variable-foraging-demand (VFD) group, were reared by mothers having a foraging task that varied between easy and difficult in 2-week blocks during the experimental rearing period. Although no treatment group differences were evident during the initial rearing period, during subsequent social challenges VFD monkeys exhibited a diminished capacity for affiliative social engagement relative to LFD monkeys and were socially subordinate to LFD monkeys.

Response of bonnet macaque dyads to an acute foraging task under different motivational conditions.

To explore behavioral patterns in bonnet macaque mother-infant dyads under environmental challenge, the motivation of infants to contact their mothers during a 1-hr foraging period was manipulated in two ways. First, sessions were given in which the infants were separated from their mothers for 3 hr prior to the foraging period. Second, sessions were given in which the infants were allowed access to food prior to the foraging period, thereby presumably reducing their motivation to separate from mother to seek food for themselves during the foraging period. Neither manipulation resulted in heightened conflict within the dyads. Separation of the infants prior to the foraging period did result, in general, in mothers forfeiting foraging task engagement to attend to their infants. The extent to which a mother exhibited this pattern correlated with her level of foraging effectiveness.

Attachment in monkey infants raised in variable- and low-demand environments.

12 bonnet macaque (Macaca radiata) mother-infant dyads were studied. For 14 weeks, beginning when the infants were a mean age of 11.2 weeks, the dyads were housed and observed under different foraging-demand conditions for the mothers: 6 dyads in a low-foraging-demand (LFD) condition and 6 dyads in a variable-foraging-demand (VFD) conditions. For VFD mothers, demand varied between low and high in 2-week blocks. Differences between the LFD and VFD groups were minimal during this period; there was, however, more maternal grooming and shorter separation bouts in the VFD group than in the LFD group. The dyads were then challenged by brief introductions to a novel environment. The challenge revealed that frequency of breaking dyadic contact and levels of play were significantly lower for the VFD infants than for the LFD infants, perhaps as a consequence of less secure attachment.

Pigtail macaque performance on a challenging joystick task has important implications for enrichment and anxiety within a captive environment.

The purpose of this study was to extend previous findings on joystick task engagement by a group of pigtail macaques. The goals were to determine the influence of task difficulty on daily levels of task activity and to test the hypothesis that previously identified preferences among identical devices at different locations derived largely from the level of anxiety induced at each location. It was found that the number of daily trials decreased when the task was made more difficult, with more time required to complete each trial with the difficult task. Preferences among locations became more pronounced with the more difficult task. Analysis of errors made on devices at different locations supported the view that preferences did derive, at least in part, from levels of induced anxiety. Locations of enrichment devices may influence not only amount of use but also levels of anxiety in captive monkeys.

The time course of recognition of novel melodies.

Seven experiments explored the time course of recognition of brief novel melodies. In a continuous-running-memory task, subjects recognized melodic transpositions following delays up to 2.0 min. The delays were either empty or filled with other melodies. Test items included exact transpositions (T), same-contour lures (SC) with altered pitch intervals, and different-contour lures (DC); DCs differed from Ts in the pattern of ups and downs of pitch. With this design, we assessed subjects' discrimination of detailed changes in pitch intervals (T/SC discrimination) as well as their discrimination of contour changes (T/DC). We used both artificial and "real" melodies. Artificial melodies differed in conformity to a musical key, being tonal or atonal. After empty delays, T/DC discrimination was superior to T/SC discrimination. Surprisingly, after filled delays, T/SC discrimination was superior to T/DC. When only filled delays were tested, T/SC discrimination did not decline over the longest delays. T/DC performance declined more than did T/SC performance across both empty and filled delays. Tonality was an important factor only for T/SC discrimination after filled delays. T/DC performance was better with rhythmically intact folk melodies than with artificial isochronous melodies. Although T/SC performance improved over filled delays, it did not overtake T/DC performance. These results suggest that (1) contour and pitch-interval information make different contributions to recognition, with contour dominating performance after brief empty delays and pitch intervals dominating after longer filled delays; (2) a coherent tonality facilitates the encoding of pitch-interval patterns of melodies; and (3) the rich melodic-rhythmic contours of real melodies facilitate T/DC discrimination. These results are discussed in terms of automatic and controlled processing of melodic information.

Persistent elevations of cerebrospinal fluid concentrations of corticotropin-releasing factor in adult nonhuman primates exposed to early-life stressors: implications for the pathophysiology of mood and anxiety disorders.

There is increasing evidence for an important role of adverse early experience on the development of major psychiatric disorders in adulthood. Corticotropin-releasing factor (CRF), an endogenous neuropeptide, is the primary physiological regulator of the mammalian stress response. Grown nonhuman primates who were exposed as infants to adverse early rearing conditions were studied to determine if long-term alterations of CRF neuronal systems had occurred following the early stressor. In comparison to monkeys reared by mothers foraging under predictable conditions, infant monkeys raised by mothers foraging under unpredictable conditions exhibited persistently elevated cerebrospinal fluid (CSF) concentrations of CRF. Because hyperactivity of CRF-releasing neurons has been implicated in the pathophysiology of certain human affective and anxiety disorders, the present finding provides a potential neurobiological mechanism by which early-life stressors may contribute to adult psychopathology.