Cytotoxic lesions of the hippocampus do not impair social recognition memory in socially housed rats

Socially housed mice with cytotoxic lesions of the hippocampus do not exhibit social recognition memory 30 min following exposure to a juvenile mouse, however the social recognition memory of singly housed rats is unimpaired. The present study tests the hypothesis that social housing of rats could render social recognition memory hippocampally dependent as seen for mice. Rats were housed with juveniles or with adults. Two social recognition one-animal tests paralleling those used with mice were carried out. Seven social discrimination two-animal tests were also given. Sham operated and hippocampally lesioned rats had normal social memory at 30 min whether socially housed for 24, 48 h, 7 or 8 days prior to testing. These findings support other results indicating the hippocampus proper is not required for normal social memory in rats. In a final experiment, rats socially housed in groups of three since weaning, were tested for 30 min and 24 h social memory. Unlike mice, rats socially housed throughout life exhibited social memory only at 30 min, but not at 24 h. Manipulations that extend social memory in rats may be required to render social memory hippocampally dependent or rats and mice may differ in the neural mediation of social memory.     

A dual-process account of digit invariance learning

Performance in the McGeorge and Burton (1990) digit invariance task was originally thought to be mediated by unconscious abstraction of a “rule” that identified the invariant feature across all study items. Subsequent explanations have suggested explicit strategy use or similarity-to-exemplar matching rather than abstraction. This paper presents data that suggest that both similarity and abstraction can be used under different task demands. Delay between study and test afforded abstraction of the invariant knowledge whereas reducing the pool of study exemplars enhanced responding based on specific similarity. These results parallel effects found in the categorization literature. Rule abstraction in this sense may be due to statistical learning of feature frequency rather than abstraction of a central tendency or a complex/conceptual rule. Categorizing responses into subjective memory states (remember/know/guess) demonstrates that neither the similarity matching nor the abstraction mechanism uses information from episodic memory. Confidence measures show that participants are more confident of responses when the prototypical representation is used but not specific similarity. Taken together, these data suggest that abstracted knowledge is not held consciously but that participants have meta-awareness of when they are using the abstracted representation.     

fMRI of parents of children with Asperger Syndrome: a pilot study

BACKGROUND: People with autism or Asperger Syndrome (AS) show altered patterns of brain activity during visual search and emotion recognition tasks. Autism and AS are genetic conditions and parents may show the 'broader autism phenotype.' AIMS: (1) To test if parents of children with AS show atypical brain activity during a visual search and an empathy task; (2) to test for sex differences during these tasks at the neural level; (3) to test if parents of children with autism are hyper-masculinized, as might be predicted by the 'extreme male brain' theory. METHOD: We used fMRI during a visual search task (the Embedded Figures Test (EFT)) and an emotion recognition test (the 'Reading the Mind in the Eyes' (or Eyes) test). SAMPLE: Twelve parents of children with AS, vs. 12 sex-matched controls. DESIGN: Factorial analysis was used to map main effects of sex, group (parents vs. controls), and sexxgroup interaction on brain function. An ordinal ANOVA also tested for regions of brain activity where females>males>fathers=mothers, to test for parental hyper-masculinization. RESULTS ON EFT TASK: Female controls showed more activity in extrastriate cortex than male controls, and both mothers and fathers showed even less activity in this area than sex-matched controls. There were no differences in group activation between mothers and fathers of children with AS. The ordinal ANOVA identified two specific regions in visual cortex (right and left, respectively) that showed the pattern Females>Males>Fathers=Mothers, both in BA 19. RESULTS ON EYES TASK: Male controls showed more activity in the left inferior frontal gyrus than female controls, and both mothers and fathers showed even more activity in this area compared to sex-matched controls. Female controls showed greater bilateral inferior frontal activation than males. This was not seen when comparing mothers to males, or mothers to fathers. The ordinal ANOVA identified two specific regions that showed the pattern Females>Males>Mothers=Fathers: left medial temporal gyrus (BA 21) and left dorsolateral prefrontal cortex (BA 44). CONCLUSIONS: Parents of children with AS show atypical brain function during both visual search and emotion recognition, in the direction of hyper-masculinization of the brain. Because of the small sample size, and lack of age-matching between parents and controls, such results constitute a pilot study that needs replicating with larger samples.     

Violent self-harm in schizophrenia

Patients with schizophrenia have a substantial lifetime suicide risk, especially by violent means. Little published work exists on self-harm (SH) in this population. The goal of this study was to examine whether patients with schizophrenia were also more likely to self-harm in a violent manner. A retrospective analysis performed on method, motive, and suicidal intent in patients with schizophrenia (n = 50) and adjustment reaction (n = 138) who presented with SH over a 3-year period found that there was no significant difference between the two groups in terms of violence of method or suicidal intent. Presence of positive symptoms of schizophrenia was not significantly associated with use of a violent method. This study suggests that the expected pattern of violent SH in schizophrenia is inaccurate and for the majority the acts are of a similar nature to those seen in adjustment reactions.     

Standardizing the psychological autopsy: addressing the Daubert standard

The psychological autopsy, as a research, clinical, and forensic tool, has gained widespread usage in suicidology over the last half century. In forensic settings, the lack of standardization and problems determining the procedure's validity and reliability pose significant issues for the procedure's admissibility under the Daubert standard of evidence. The Daubert standard requires that evidence must be founded on scientific knowledge and established five guidelines for judicial decisions regarding the admissibility of expert testimony. In this paper we examine expert opinion regarding the psychological autopsy and recommend a standardized protocol or template regarding areas and lines of inquiry for a psychological autopsy used in legal cases.     

Enhancing academic performance by strengthening class-inclusion reasoning

Class inclusion is an early form of abstract thought that requires logical rather than perceptually based inferences plus an appreciation of part-whole relationships (B. Inhelder and J. Piaget, 1959/1964). The authors randomly assigned 2 groups of first graders who were having academic difficulties to be instructed on either class inclusion or phonics. Results showed a significant linear relation between individual children's mastery of class inclusion and their scores on the Cognitive Abilities Test Form 6 (D. F. Lohman and E. P. Hagen, 2001) verbal and quantitative measures of reasoning. The authors also found a significant linear relation between mastery of class inclusion and improvement in report card marks issued by teachers who were blind to the children's group assignment.