The effect of "social" discriminative cues on probability learning.
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Serotonin(6) (5-HT(6)) receptors are almost exclusively located in the central nervous system. High expression in the hippocampus, nucleus accumbens and striatum is consistent with a potential role in cognition and psychosis. The availability of potent, selective and brain-penetrating 5-HT(6) antagonists such as RO4368554 allows further characterization of the role of the 5-HT(6) receptor in these processes. Herein, we tested RO4368554 in several cognition tasks, as well as sensorimotor gating tests. Using scopolamine-impaired and unimpaired adult male rats, RO4368554 was given in novel object discrimination, social recognition, social discrimination, Morris water maze, passive avoidance and autoshaping procedures. RO4368554 reversed the effects of scopolamine in novel object discrimination (active doses in mg/kg, i.p., 3, 10), social recognition (3, 10), social discrimination (1, 3, 10) and passive avoidance (10, 30 i.p. and 100 p.o.) tasks. In unimpaired rats, RO4368554 enhanced object discrimination (3, 10; 4-h forgetting interval) and autoshaping learning (3), but was inactive in a water maze task (doses tested: 1-10 mg/kg, i.p.). In tests sensitive to antipsychotics, RO4368554 did not reverse sensorimotor gating deficits induced by the psychostimulants dizocilpine and amphetamine (doses tested: 1-30 mg/kg, i.p.) or neonatal lesion of the ventral hippocampus (1-10 mg/kg, i.p.). In conclusion, RO4368554 enhanced learning and memory processes in unimpaired and scopolamine-impaired rats, supporting the notion that the cognitive enhancing effects of 5-HT(6) receptor antagonists involve modulation of cholinergic neurotransmission.
Attitudes towards mental illness were measured in a probability sample of 1574 male and female adults, residents of two boroughs in the greater Athens area before the development of community mental health services in the area. The objective of this study was to identify the components of these attitudes, taking into account the fact that public opinions about mental illness influence the utilization of community mental health services and the level of reintegration of the mentally disabled into society. The instrument used to measure attitudinal dimensions was the Cohen and Struening Opinion about Mental Illness (O.M.I.) scale. Factor analysis revealed five attitude dimensions: social discrimination, social restriction, social care, integration, and etiology. Among the socio-demographic variables age, education, occupational status and place of residence up to 18 years of age affected the factors mainly, reflecting social discrimination and restriction. O.M.I. factor scores underlying the need for social care and reintegration of the mentally ill into society were found to be socially invariant, implying the need for social care and more humane treatment methods for mental patients. Certain population groups responded with rejection or suspicion and considerable fear of the mentally ill, indicating the necessity for the planning of appropriate community mental health intervention programs parallel to the development of community mental health services and psychiatric reforms in Greece.
Social categorization under minimal group conditions reliably produces intergroup discrimination. It is proposed that this might be because the minimal group paradigm engenders high levels of subjective uncertainty among participants, which causes them to use the categorization to define self and thus identify with the minimal group. Uncertainty is generally an aversive state which may be resolved by identification (Hogg, 1996; Hogg & Abrams, 1993). Thus, people may identify with social categories (and express discrimination) when identification resolves uncertainty. To investigate this idea a standard minimal group experiment was conducted, in which the three independent variables of categorizations, task uncertainty and situational uncertainty were manipulated in a 2 x 2 x 2 factorial between-subjects design. Point distribution strategies were measured along with in-group identification, self-esteem, social awareness and, at three occasions, uncertainty about the task and situation. As predicted, under conditions of high task or situational uncertainty, categorized participants identified more with their minimal in-group and exhibited more intergroup discrimination than other participants. There was also some evidence that identification reduced uncertainty. There was only partial support for the mediational role of identification, and similarly, for self-esteem as a derivative motive. These findings are interpreted as supporting an uncertainty reduction model of social identification and group motivation.
The relationship between early life events and the socialized and undersocialized dimensions of conduct disorder was investigated. Subjects were 40 incarcerated male delinquents and their mothers. The mothers were administered the Children's Life Events Questionnaire and the Developmental Questionnaire. Youths were administered the Adolescent Parent Relations Scale. The results indicated that the undersocialized delinquents had a greater number of stressful life events during their first 4 years of life than did the socialized delinquents. Discriminant function analysis indicated that stressful life events during the 2nd and 4th years were the most important predictors of membership in the undersocialized group. The discriminant function generated was able to classify 82.5% of the sample correctly. The remaining variables did not significantly discriminate the groups.
Discrimination of individual conspecifics by their odors has been reported for many mammalian species, but little information is available on the brain mechanisms underlying such discrimination. A previous study reported that large parahippocampal lesions, centered on entorhinal cortex but extending into adjacent areas of the brain, eliminated female hamsters' ability to discriminate the flank gland odors of different individuals, as tested with habituation-dishabituation methods. The current study examined the effects of lesions restricted to the lateral entorhinal area on such discriminations. Female hamsters were tested in several types of habituation procedure that differed across a sequence of trials in the locations of familiar and novel social odors. Discrimination of two individuals' odors depended on the sequences of locations of the odors, indicating that odor identity and location were simultaneously salient to female hamsters. Lesions of lateral entorhinal area interfered with this spatial-olfactory discrimination. When confounding spatial cues were eliminated, hamsters did discriminate between novel and familiar odors, and lesions in the entorhinal area did not eliminate this ability. Thus, although the lateral entorhinal area is not necessary for individual odor discrimination, it is involved in processing odor-place combinations.
Social representation theory was used as a heuristic framework for investigating preadolescents' (193 Dutch and ethnic minority respondents between 10 and 13 years of age) understanding of discrimination in the Netherlands. Shared beliefs and understandings were found regarding when a specific act was considered discriminatory, who the actors were, and why the discrimination occurred. The prototypical example of discrimination was a situation in which a Dutch child called a minority child names without an acceptable reason. Discrimination was seen to a lesser degree as unequal division of valued things and as social exclusion. Consistent with social representation theory and contrary to common belief, there were very few differences in understanding of discrimination between ethnic majority and minority respondents. No differences were found for age and gender.
Orbital/agranular insular (ORB/AI) cortex has been implicated in traditional olfactory learning tasks and social behavior but its precise role in discriminating-learning social odors is not known. Female golden hamsters received aspiration lesions of ORB/AI or dorsomedial (DM) frontal cortex and were tested for their ability to (a) discriminate between odors of individual males in a habituation-discrimination task, (b) show preferences for male over female odors, and (c) scent-mark in response to male odors. Lesioned females readily discriminated between scents of individual males. Neither lesion altered female preferences for male odors. Females with DM lesions showed increased levels of scent marking to male odors, but those with ORB/AI cortex lesions did not differ from controls. Thus, ORB/AI cortex does not appear to be critical for discrimination of odors of individuals or sex or for scent-marking responses based on these discriminations.
Caffeine, a non-selective adenosine receptor antagonist, has been suggested as a potential drug to counteract age-related cognitive decline since critical changes in adenosinergic neurotransmission occur with aging. In the present study, olfactory discrimination and short-term social memory of 3, 6, 12 and 18 month-old rats were assessed with the olfactory discrimination and social recognition tasks, respectively. The actions of caffeine (3.0, 10.0 and 30.0 mg/kg, i.p.), the A1 receptor antagonist DPCPX (1.0 and 3.0 mg/kg, i.p.) and the A2A receptor antagonist ZM241385 (0.5 and 1.0 mg/kg, i.p.) in relation to age-related effects on olfactory functions were also studied. The 12 and 18 month-old rats exhibited significantly impaired performance in both models, demonstrating deficits in their odor discrimination and in their ability to recognize a juvenile rat after a short period of time. Acute treatment with caffeine or ZM241385, but not with DPCPX, reversed these age-related olfactory deficits. The present results suggest the participation of adenosine receptors in the control of olfactory functions and confirm the potential of caffeine for the treatment of aged-related cognitive decline.
Sixty-two adults with mental retardation of heterogeneous etiology performed four facial emotion discrimination tasks and two facial nonemotion tasks. Staff members familiar with the participants completed measures of social adjustment (the Socialization and Communication domains of the Vineland Adaptive Behavior Scales and the Social Performance Survey Schedule). All facial discrimination tasks had very good reliability (internal consistency), but only some of the tasks correlated with measures of social adjustment. Furthermore, no evidence was found that emotion tasks and nonemotion tasks assessed different social constructs. Emotion tasks in which participants were presented with visual emotion stimuli correlated significantly with prosocial behavior, whereas those with verbal emotion stimuli did not.
Muscarinic receptor agonists have been suggested as potential drugs to counteract age-related cognitive decline since critical changes in cholinergic system occur with aging. Recently, we demonstrated that single administration of the non-selective muscarinic receptor agonist pilocarpine prevents age-related spatial learning impairments in rats. In addition, increasing evidence suggests that areas in the central nervous system processing olfactory information are affected at the early stages of age-related diseases, such as Alzheimer's disease, and that specific olfactory testing may represent an important tool in the diagnosis of these diseases. In the present study, olfactory discrimination and short-term social memory of 3 and 24 month-old rats were assessed with the olfactory discrimination and social recognition memory tasks, respectively. The actions of the repeated treatment with pilocarpine (30 mg/kg, i.p.; once per day for 21 days) in relation to age-related effects on olfactory and cognitive functions were also studied. The 24 month-old rats exhibited significantly impaired performance in both models, demonstrating deficits in their odour discrimination and in their ability to recognize a juvenile rat after a short period of time. The treatment with pilocarpine improved in a specific manner these age-related deficits in 24 month-old rats without altering their motor performance. The present results extend the notion of the participation of muscarinic receptors in control of olfactory functions and reinforce the potential of muscarinic receptor agonists for the treatment of age-related cognitive decline.
Disruption of circadian rhythm can impair long-term passive avoidance memory of rats and mice. The present study investigated whether disruption of circadian rhythm can also impair social memory of male rats. Social memory was assessed using the social discrimination test, in which a short-term olfactory memory is formed by social interaction with a juvenile rat during a learning trial. After an intertrial interval, a retrieval trial is performed, in which social memory is expressed as a decreased attention paid to the same juvenile as compared to a new juvenile. First, the social memory at four different time points across the light-dark cycle was measured with an intertrial interval of 10 or 25 min. There was no significant circadian variation of social memory across the light-dark cycle. Subsequently, the effect of a -6 or 12-h phase shift on social memory was studied. These phase shifts were previously found to impair long-term passive avoidance memory. However, no effect of either phase shift was observed in the social discrimination test. It is concluded that the disruption of circadian rhythm had no effect on the social memory of rats. Differences between short-term social memory and long-term passive avoidance memory are discussed in relation to their apparent differential susceptibility to the effects of circadian rhythm disruption.
RATIONALE: Endogenous vasopressin is involved in the social memory of the male rat and administration of exogenous vasopressin improves social memory. These findings are mainly based on studies using sexually experienced males that were tested in the social recognition test. OBJECTIVE: The present study was aimed to establish whether the modulation of social memory by vasopressin fragments depends on the sexual experience of the male rat. For this purpose, the social discrimination test was used, since this test is more suitable than the social recognition test for measuring social memory in sexually naive males. METHODS: Male rats were tested in the social discrimination test and treated subcutaneously with the vasopressin metabolite [pGlu4,Cyt6]vasopressin-(4-8) (VP4-8). VP4-8 shares with vasopressin the effects on memory processes but lacks the peripheral effects of vasopressin. RESULTS: VP4-8 (1 microgram/kg) acutely improved the social memory of sexually experienced male rats, confirming previous reports. However, in sexually naive males VP4-8 failed to improve social memory in doses ranging from 0.1 microgram/kg to 1 microgram/kg. Instead, 1 microgram/kg VP4-8 or 6 micrograms/kg desglycinamide-vasopressin were found to exert a delayed effect in sexually naive rats. This delayed effect resulted in an improved social memory 2 days after administration. CONCLUSIONS: Vasopressin sensitisation is discussed as a possible underlying mechanism of the observed delayed effect of vasopressin fragments. It is concluded that in male rats sexual experience can influence the modulation of social memory by vasopressin.
Combining survey and ethnographic data, this research examined differences in the risk factors associated with needle sharing amongst intravenous drug users (IDUs) in the Sichuan Province of China. A comparison was made between the province's majority Han population and its Yi minority. We developed a theoretical framework consisting of risk factors at the individual level (including risk factors such as lack of AIDS knowledge, low self-efficacy, and economic pressure), interpersonal level (having an IDU primary partner and lack of family support), and community level (social discrimination). The findings suggested that the Yi minority group was more socially disadvantaged and had a higher risk of contracting HIV than the Han group. Furthermore, the factors that put them at risk were different to those which affected the Han group. OLS regression results showed that, for Han IDUs, needle sharing was positively associated with having an IDU primary partner and with economic pressure. On the other hand, for the minority group, needle sharing was significantly associated with being male, AIDS knowledge, the lack of family support, and social discrimination. These findings highlight the need for HIV prevention work to target marginalized populations in China, such as ethnic minorities, and to tailor appropriate prevention strategies to meet the specific needs of different groups.