The perceptual-mnemonic/feature conjunction model of perirhinal cortex function.

The perirhinal cortex was once thought to be "silent cortex", virtually ignored by researchers interested in the neurobiology of learning and memory. Following studies of brain damage associated with cases of amnesia, perirhinal cortex is now widely regarded as part of a "medial temporal lobe (MTL) memory system". This system is thought to be more or less functionally homogeneous, having a special role in declarative memory, and making little or no contribution to other functions such as perception. In the present article, we summarize an alternative view. First, we propose that components of the putative MTL system such as the hippocampus and perirhinal cortex have distinct and dissociable functions. Second, we provide evidence that the perirhinal cortex has a role in visual discrimination. In addition, we propose a specific role for perirhinal cortex in visual discrimination: the contribution of complex conjunctive representations to the solution of visual discrimination problems with a high degree of "feature ambiguity". These proposals constitute a new view of perirhinal cortex function, one that does not assume strict modularity of function in the occipito-temporal visual stream, but replaces this idea with the notion of a hierarchical representational continuum.     

Civilian PTSD scales: relationships with trait characteristics and everyday distress

Strong associations between civilian posttraumatic stress disorder (PTSD) scales and measures of general psychological distress suggest that the scales are nonspecific to PTSD. Three common PTSD scales were administered to 122 undergraduates who had experienced an emotionally salient, nontraumatic event: a college examination. Results indicated that normal levels of anxiety associated with the examination were positively correlated with scores on the Impact of Event Scale-Revised, Revised Civilian Mississippi Scale, and PTSD Checklist-Civilian Version. Multiple regression analyses indicated that substantial variance in the PTSD scales was accounted for by trait characteristics such as negative and positive affectivity and affect intensity (R2 .29 to .53). Negative affectivity correlated as highly with PTSD measures (r = .46 to .71) as those measures correlated with each other (r = .48 to .65). A high proportion of participants exceeded clinical cutoffs on these measures. The findings suggest that these PTSD scales may be overly sensitive to nontraumatic stressors such as everyday distress and trait characteristics.     

Enhancement of auditory fear conditioning after housing in a complex environment is attenuated by prior treatment with amphetamine

Prior exposure to drugs of abuse has been shown to occlude the structural plasticity associated with living in a complex environment. Amphetamine treatment may also occlude some cognitive advantages normally associated with living in a complex environment. To test this hypothesis we examined the influence of prior exposure to amphetamine on fear conditioning in rats housed in either a standard or complex environment. Housing in a complex environment facilitated fear learning to an auditory conditioned stimulus (CS), but not to the training context, relative to animals housed singly or in a social group. Prior treatment with amphetamine eliminated this effect. These results indicate that living in a complex environment facilitates conditional freezing to an auditory CS, and that this effect is abolished by pretreatment with amphetamine.     

Dietary CDP-choline supplementation prevents memory impairment caused by impoverished environmental conditions in rats

We previously showed that dietary cytidine (5')-diphosphocholine (CDP-choline) supplementation could protect against the development of memory deficits in aging rats. In the present study, younger rats exposed to impoverished environmental conditions and manifesting hippocampal-dependent memory impairments similar to those observed in the aging rodents were given CDP-choline, and its effects on this cognitive deficit were assessed. Male Sprague-Dawley rats reared for 3 mo in impoverished (IC) or enriched environmental (EC) conditions concurrently received either a control diet or a diet supplemented with CDP-choline (approximately 500 mg/kg/d). After 3 mo, rats were trained to perform spatial and cued versions of the Morris water maze, and their rates of acquisition and retention were compared. Impoverished rats exhibited a selective deficit in hippocampal-dependent spatial memory which could be ameliorated by feeding them CDP-choline. The CDP-choline had no memory-enhancing effect in enriched rats, nor did it prevent the memory impairment of impoverished rats if the animals consumed it for the initial or final months instead of for the entire 3-mo period. These findings indicate that long-term dietary CDP-choline supplementation can ameliorate the hippocampal-dependent memory impairment caused by impoverished environmental conditions in rats, and suggest that its actions result, in part, from a long-term effect such as enhanced membrane phosphatide synthesis, an effect shown to require long-term dietary supplementation with CDP-choline.     

Differential induction of c-Jun and Fos-like proteins in rat hippocampus and dorsal striatum after training in two water maze tasks

Research examining the neuroanatomical bases of memory in mammals suggests that the hippocampus and dorsal striatum are parts of independent memory systems that mediate "cognitive" and stimulus-response "habit" memory, respectively. At the molecular level, increasing evidence indicates a role for immediate early gene (IEG) expression in memory formation. The present experiment examined whether acquisition of cognitive and habit memory result in differential patterns of IEG protein product expression in these two brain structures. Adult male Long-Evans rats were trained in either a hippocampal-dependent spatial water maze task, or a dorsal striatal-dependent cued water maze task. Ninety minutes after task acquisition, brains were removed and processed for immunocytochemical procedures, and the number of cells expressing Fos-like immunoreactivity (Fos-like-IR) and c-Jun-IR in sections from the dorsal hippocampus and the dorsal striatum were counted. In the dorsal hippocampus of rats trained in the spatial task, there were significantly more c-Jun-IR pyramidal cells in the CA1 and CA3 regions, relative to rats that had acquired the cued task, yoked controls (free-swim), or na?ve (home cage) rats. Relative to rats receiving cued task training and control conditions, increases in Fos-like IR were also observed in the CA1 region of rats trained in the spatial task. In rats that had acquired the cued task, patches of c-Jun-IR were observed in the posteroventral striatum; no such patches were evident in rats trained in the spatial task, yoked-control rats, or na?ve rats. The results demonstrate that IEG protein product expression is up-regulated in a task-dependent and brain structure-specific manner shortly after acquisition of cognitive and habit memory tasks.     

Asian and Pacific Island American students' acculturation and etiology beliefs about typical counseling presenting problems

Asian American Pacific Island college students (N = 93) completed measures of acculturation and mental health worldview, in the form of beliefs about the likely causes of 24 typical counseling presenting problems. A criterion sample of 27 staff from 2 university counseling centers reported their beliefs about the most likely cause of the same 24 problems for a typical client. A response similarity index was calculated, with higher scores reflecting greater similarity between student and counselor mental health worldviews. Results suggest that higher acculturation was associated with greater level of match between the students' etiology beliefs and those of counselors. The greatest differences were observed for serious personal problems, whereas there was more belief convergence about causes of academic problems.     

The Asian American values scale--multidimensional: development, reliability, and validity

The development of the 42-item Asian American Values Scale-Multidimensional (AAVS-M) is presented. In Study 1, data from 163 Asian American respondents were subjected to a principal components analysis, which reduced the initial set of 180 items to 42 items divided into 5 components: collectivism, conformity to norms, emotional self-control, family recognition through achievement, and humility. The data also revealed initial evidence of the AAVS-M total and subscale scores' reliability and validity. In Study 2, data from 189 Asian American respondents were subjected to a confirmatory factor analysis, which supported a hierarchical factor structure underlying the AAVS-M. Additional reliability and validity evidence of AAVS-M total and subscale scores were found. In Study 3, data from 38 Asian American respondents yielded evidence of AAVS-M total and subscale scores' test-retest reliability.     

Implicit self-attitudes predict spontaneous affect in daily life

In 2 studies, the authors examined the degree to which implicit self-attitudes predicted people's spontaneous affective experiences in daily life. Across both studies, implicit attitudes toward the self (as measured by Implicit Association Tests) strongly predicted negative feeling states (as measured by computerized experience-sampling procedures), suggesting that implicit self-attitudes may be linked to changes in undifferentiated negative affect. Explicit attitudes toward the self generally did not account for these relations. Findings extend understanding of the factors that contribute to experienced affect and are the first to empirically link implicit self-attitudes with phenomenological affective experience in real-life settings over time.     

How does context affect intimate relationships? linking external stress and cognitive processes within marriage

Stressors external to the marriage frequently affect the way spouses evaluate their marital quality. To date, however, understanding of the interplay between external stress and internal relationship processes has been limited in two ways. First, research has generally examined only the short-term consequences of stress. Second, the mechanisms through which external stressors influence relationship outcomes are unclear. This study addressed both limitations by examining relationship cognitions that may mediate the effects of external stress throughout 4 years of marriage. Analyses confirmed that stressful experiences were associated with the trajectory of marital quality overtime. Furthermore, both the content and the organization of spouses' specific relationship cognitions mediated this effect. That is, stress negatively influenced the nature of spouses' marital perceptions as well as the way spouses interpreted and processed those perceptions. These findings draw attention to ways that the context of relationships shapes and constrains relationship processes.