REM sleep deprivation increases early morning pineal melatonin in castrated rats

Recently nighttime melatonin levels have been shown to be attenuated in depressive patients or patients with dementia of the Alzheimer type. On the other hand, depression can be transiently relieved by deprivation of rapid eye movement sleep. Since exogenous melatonin administration increases rapid eye movement sleep and slow wave sleep in the rat, could rapid eye movement sleep deprivation then inversely influence endogenous melatonin production? We found indices that in castrated Wistar rats 4 days of rapid eye movement sleep deprivation by the cuff pedestal method elevates the pineal content of melatonin by a factor of two at 1 to 2 h after light onset. Rapid eye movement sleep is thus suggested to influence pineal activity. This mechanism might be involved in the human depression-alleviating effect of rapid eye movement sleep deprivation.     

Delayed-onset sensitization emerges after dishabituation in developing Aplysia.

A recent study of the development of nonassociative learning in the siphon withdrawal reflex of Aplysia showed that dishabituation (facilitation of an habituated response) and sensitization (facilitation of a nonhabituated response) emerge according to different developmental timetables: dishabituation precedes sensitization by approximately 60 days (Rankin & Carew, 1988). Both forms of facilitation of the reflex were observed within 90 s of an electrical shock to the tail. However, more recent work by Marcus and colleagues (1988) in adult animals revealed that sensitization can have a delayed onset of 20-30 min after a strong tail shock. Since the developmental study of Rankin and Carew (1988) only tested the reflex for 10 min after tail shock, it is possible that sensitization was in fact present at earlier developmental stages, but was undetected. To examine this question, in the present study we utilized a longer (40-50 min) post-shock observation period to determine whether delayed-onset sensitization is exhibited in juvenile Aplysia, and if so, when it is expressed during development. In our first experiment, we found that Early Stage 12 juveniles (80-95 days after metamorphosis) showed significant delayed-onset sensitization 30-50 min after a strong tail shock. In a second experiment, we found that delayed-onset sensitization was absent in Stage 11 animals (20-70 days after metamorphosis). Thus delayed-onset sensitization emerges in Early Stage 12. The fact that the birthdate of delayed-onset sensitization is at least 30 days after that of dishabituation (Rankin & Carew, 1987, 1988) supports the hypothesis that these two forms of nonassociative learning may have at least partly different underlying mechanisms.     

Intraseptal administration of bicuculline produces working memory impairments in the rat.

Male Sprague-Dawley rats, trained to perform a delayed-non-match-to-sample eight-arm radial maze task, were implanted with a single cannula aimed at the medial septal nucleus. A within-subjects design was utilized to examine the effects of intraseptal administration of bicuculline (0.5 micrograms) on performance of this task with 1- and 4-h delay intervals imposed between choices four and five. Administration of bicuculline immediately following the first four choices produced an impairment in maze performance at both a 1- and a 4-h delay interval. This treatment also produced an increase in latency per choice. Bicuculline-induced impairments were not observed when administered 2 h following the predelay session (2 h prior to testing). These data support previous observations that pharmacological manipulation of GABAergic activity within the septum modifies working memory processes.     

Reversal of retrieval impairment caused by retroactive interference on a two-way active avoidance task in rats

Rats were exposed to an open field with flashing light (OFL; 60-W lamp, 30 Hz, for 7 min) 2 h after training and/or 2 h before testing in a two-way active avoidance task (30 trials, 0.5-mA footshock). Post-training OFL presentation caused retroactive interference, i.e., a retrieval impairment/amnesia for the avoidance task. Pretest OFL exposure reversed the post-training OFL-induced retrieval deficit. Diazepam (2.0 mg/kg), atropine (2.0 mg/kg), and methylatropine (0.1 mg/kg) administered before post-training OFL presentation blocked the OFL amnesic effect. However, these drugs did not counteract the pretest OFL-induced recovery of retrieval. Atropine and methylatropine administered 2 h before testing to rats receiving only post-training OFL presentation canceled the OFL-interfering effect. These results suggest: (1) that the amnesic effect of post-training OFL is due to failure of retrieval of the avoidance task, (2) that the reversal of this retrieval impairment by pretest OFL exposure may involve either priming or state-dependent mechanisms, and (3) that there are different modulatory mechanisms involved in post-training and pretest OFL effects.     

Seeing the World in Pink and Blue: Developing and Exploring a New Measure of Essentialistic Thinking about Gender

Sex Roles - Essentialism, or the belief that certain categories have fundamental, intrinsic, and stable essences, pervasively influences social judgments. Among the many groupings that describe...     

Internalizing problems and their impact on the relation between callous-unemotional traits,narcissism, and aggression

Narcissism and callous-unemotional (CU) traits have demonstrated relations with youth aggression across studies. However, different forms of narcissism and internalizing problems may exacerbate the relation between CU traits and aggression. To that end, the current study examined the degree to which interactions among internalizing problems, CU traits, and dimensions of narcissism related to aggression in a sample of 219 adolescents (83.1% males), ages 16–19, enrolled in a military-style residential program. Consistent with previous research, psychopathy-linked narcissism significantly moderated the relation between CU traits and aggression. Addtionally, self-reported aggression was highest among adolescents who endorsed high levels of CU traits, psychopathy-linked narcissism, and internalizing problems. The same pattern of results was not evident for other forms of narcissism. These results suggest that internalizing problems further increase the probability of aggression among adolescents with psychopathic tendencies (i.e., CU traits, psychopathy-linked narcissism). Further implications are discussed.     

A Preliminary Longitudinal Study of Multicultural Competence in Counselor Education

The purpose of this study was to investigate longitudinal changes in master’s-level counselor trainees’ (N = 78) self-perceptions of their multicultural counseling competence over the course of their counseling program. Multilevel modeling results indicated an increase in scores across 3 time points. The authors discuss study limitations and how counselors and counselor educators can incorporate the study’s findings into their practice and into the education and supervision of counselor trainees.     

Semantic diversity in paired-associate learning: Further evidence for the information accumulation perspective of cognitive aging

Psychonomic Bulletin & Review - Normal aging is often associated with a performance decline on various cognitive tests, including paired associate learning (PAL), where participants are asked...     

Face detection in 2‐ to 6‐month‐old infants is influenced by gaze direction and species

Humans detect faces efficiently from a young age. Face detection is critical for infants to identify and learn from relevant social stimuli in their environments. Faces with eye contact are an especially salient stimulus, and attention to the eyes in infancy is linked to the emergence of later sociality. Despite the importance of both of these early social skills—attending to faces and attending to the eyes—surprisingly little is known about how they interact. We used eye tracking to explore whether eye contact influences infants' face detection. Longitudinally, we examined 2‐, 4‐, and 6‐month‐olds' (N = 65) visual scanning of complex image arrays with human and animal faces varying in eye contact and head orientation. Across all ages, infants displayed superior detection of faces with eye contact; however, this effect varied as a function of species and head orientation. Infants were more attentive to human than animal faces and were more sensitive to eye and head orientation for human faces compared to animal faces. Unexpectedly, human faces with both averted heads and eyes received the most attention. This pattern may reflect the early emergence of gaze following—the ability to look where another individual looks—which begins to develop around this age. Infants may be especially interested in averted gaze faces, providing early scaffolding for joint attention. This study represents the first investigation to document infants' attention patterns to faces systematically varying in their attentional states. Together, these findings suggest that infants develop early, specialized functional conspecific face detection.     

Irrelevant‐action imitation is short‐term and contextual: Evidence from two under‐studied populations

Across the lifespan and across populations, humans ‘overimitate’ causally unnecessary behaviors. Such irrelevant‐action imitation facilitates faithful cultural transmission, but its immediate benefits to the imitator are controversial. Over short time scales, irrelevant‐action imitation may bootstrap artifact exploration or interpersonal affiliation, and over longer time scales it may facilitate acquisition of either causal models or social conventions. To investigate these putative functions, we recruited community samples from two under‐studied populations: Yasawa, Fiji, and Huatasani, Peru. We use a two‐action puzzle box: first after a video demonstration, and again one month later. Treating age as a continuous variable, we reveal divergent developmental trajectories across sites. Yasawans (44 adults, M = 39.9 years, 23 women; 42 children, M = 9.8 years, 26 girls) resemble documented patterns, with irrelevant‐action imitation increasing across childhood and plateauing in adulthood. In contrast, Huatasaneños (48 adults, M = 37.6 years, 33 women; 47 children, M = 9.3 years, 13 girls) evince a parabolic trajectory: adults at the site show the lowest irrelevant‐action imitation of any demographic set in our sample. In addition, all age sets in both populations reduce their irrelevant actions at Time 2, but do not reduce their relevant‐action imitation or goal attainment. Taken together, and considering the local cultural contexts, our results suggest that irrelevant‐action imitation serves a short‐term function and is sensitive to the social context of the demonstration.