Semantic memory disorders

Semantic memory encompasses knowledge of objects, facts and words. A number of brain regions are probably involved, but the left infero-lateral temporal lobe appears to play a key role. The separability of semantic memory from episodic (or autobiographical) memory is a focus of current debate. Impaired semantic memory is a common feature of Alzheimer's disease but is invariably overshadowed by a profound deficit in episodic memory. In semantic dementia, a rarer disorder associated with focal temporal-lobe atrophy, there is selective loss of semantic memory, characterized by preservation of superordinate knowledge of words, and objects, but loss of finer-grained information. This pattern can be interpreted as a degradation of features from a distributed network of semantic representations. Following Herpes simplex encephalitis, patients sometimes show disproportionate loss of knowledge for natural kinds (e.g. animals) with relative preservation of knowledge about artefacts, this may reflect differential damage to neural systems critical for perceptual as opposed to functional features, perceptual properties being more salient in knowledge about natural kinds.     

FEMALE VS. MALE ABSENCE RATES: A TEMPORAL ANALYSIS

The purpose of this research is to test the importance of temporal trends within absenteeism data for males and females. The data support previous findings of higher absenteeism rates for women when compared to men. The data also indicate the importance of temporal trends as suggested by Dansereau, Alutto, and Markham (1978). Conclusions are drawn concerning the use of absence rates as dependent variables.     

JOB-RELATEDNESS OF A POSTTRAINING JOB KNOWLEDGE CRITERION USE TO ASSESS VALIDITY AND TEST FAIRNESS

Significant job-relatedness was found for a posttraining job knowledge test criterion using an application of Lawshe's content validity method. The aide test was used as a criterion to assess the predictive validity of a vocabulary test and a civil service test with samples of black ( N = 43) and white ( N = 62) psychiatric aides. Significant validities were found on both tests, but a vocabulary test proved to be the better predictor of the criterion in both samples. The obtained validities were discussed in terms of differential validity, test fairness, and sample size. This study demonstrated that a content validity method could be applied to criteria as well as selection tests. It was concluded that content validity methods may be able to help solve the problem of criterion relevance in validation research by providing quantitative evidence of the job-relatedness of criteria.     

Cognitive behavior therapy for fear of flying: sustainability of treatment gains after September 11

This study examines the long-term efficacy of cognitive-behavioral therapy (CBT) for fear of flying (FOF) after a catastrophic fear-relevant event, the September 11, 2001, terrorist attacks. Participants (N = 115) were randomly assigned to and completed treatment for FOF using 8 sessions of either virtual reality exposure therapy (VRE) or standard exposure therapy (SE) prior to September 11, 2001. Individuals were reassessed in June, 2002, an average of 2.3 years after treatment, with a response rate of 48% (n = 55). Analyses were run on the original data and, using multiple imputation procedures, on imputed data for the full sample. Individuals maintained or improved upon gains made in treatment as measured by standardized FOF questionnaires and by number of flights taken. There were no differences between VRE and SE. Thus, results suggest that individuals previously treated for FOF with cognitive-behavioral therapy can maintain treatment gains in the face of a catastrophic fear-relevant event, even years after treatment is completed.     

Virtual reality exposure therapy and standard (in vivo) exposure therapy in the treatment of fear of flying

This controlled clinical trial tested virtual reality exposure (VRE) therapy for the fear of flying (FOF), a relatively new and innovative way to do exposure therapy, and compared it to standard (in vivo) exposure therapy (SE) and a wait list (WL) control with a 6- and 12-month follow-up. Eighty-three participants with FOF were randomly assigned to VRE, SE, or WL. Seventy-five participants, 25 per group, completed the study. Twenty-three WL participants completed randomly assigned treatment following the waiting period. Treatment consisted of 4 sessions of anxiety management training followed either by exposure to a virtual airplane (VRE) or an actual airplane at the airport (SE) conducted over 6 weeks. Results indicate that VRE was superior to WL on all measures, including willingness to fly on the posttreatment flight (76% for VRE and SE; 20% for WL). VRE and SE were essentially equivalent on standardized questionnaires, willingness to fly, anxiety ratings during the flight, self-ratings of improvement, and patient satisfaction with treatment. Follow-up assessments at 6 and 12 months indicated that treatment gains were maintained, with more than 70% of respondents from both groups reporting continued flying at follow-up. Based on these findings, the use of VRE in the treatment of FOF was supported in this controlled study, suggesting that experiences in the virtual world can change experiences in the real world.     

Neurotoxic dorsal CA1 lesions versus 4 VO ischaemic lesions: behavioural comparisons

Anterograde amnesia, a common consequence of transient cerebral ischaemia, has been attributed to cell loss in the hippocampal CA1 subfield. However, variable, widespread damage outside hippocampal CA1 can also occur following ischaemia. We compared the functional consequences of ischaemia and ibotenate acid CA1 lesions on 2 spatial memory tasks (water maze 'place' and 'matching-to-position') to address the possibility that extra-CA1 loss contributes to ischaemia-induced memory deficits in the rat. During place task acquisition, ischaemic rats showed deficits on more measures than ibotenic rats, and during a 1 min probe trial, only ischaemic rats were impaired. On the matching-to-position task, ibotenic rats showed greater impairment than ischaemic rats in terms of one-trial learning, whereas ischaemic rats were more impaired after Trial 2. Ischaemia and ibotenic acid lesions resulted in equivalent CA1 loss, but silver impregnation revealed additional extra-CA1 cell loss in ischaemic rats. Together with the greater behavioural deficits of ischaemic rats, these data indicate a role for extra-CA1 cell loss in ischaemia-induced memory impairments in both animals and humans.