Fiona J. Bardenhagen

Cognitive Components in Perseverative and Nonperseverative Errors on the Object Alternation Task

Knowledge of response rules in the object alternation (OA) task was experimentally manipulated in 20 alcohol-dependent men and 20 controls. The results suggest that perseverative and nonperseverative errors in OA are under the direct control of task-specific knowledge which must be induced and retained from trial to trial, and that impaired response inhibition is not solely responsible for poor performance on these tasks. The demonstration of a cognitive contribution to poor performance on the OA task suggests that rule induction must be achieved before successful response selection and inhibition can take place. We conclude by discussing implications for our understanding of other delayed response tasks and clinical tests of prefrontal function (e.g., the Wisconsin Card Sorting Test (WCST) and the Halstead Category Test).

Exploring the Dimensionality of Digit Span

The Digit Span subtest from the Wechsler Scales is used to measure Freedom from Distractibility or Working Memory. Some published research suggests that Digit Span forward should be interpreted differently from Digit Span backward. The present study explored the dimensionality of the Wechsler Memory Scale–III Digit Span (forward and backward) items in a sample of heterogeneous neuroscience patients (n = 267) using confirmatory factor analysis (CFA) for dichotomous items. Results suggested that four correlated factors underlie Digit Span, reflecting easy and hard items in both forward and backward presentation orders. The model for Digit Span was then cross-validated in a seizure disorders sample (n = 223) by replication of the CFA and by examination of measurement invariance. Measurement invariance tests of the precise numerical generalization of trait estimation across groups. Results supported measurement invariance and it was concluded that forward and backward digit span scores should be interpreted as measures of the same cognitive ability.

Left posteroventral pallidotomy results in a deficit in verbal memory

Whilst pallidotomy is emerging as a popular approach to the treatment to Parkinsons disease, little is yet known about the cognitive effects of this procedure. This study presents 19 patients (6 right, 13 left) who were assessed both before and after the procedure on a battery of cognitive tests. The results indicate that subjects with left-sided lesions display significant decline in verbal memory between one and three months following the procedure. The results are consistent with the notion of either a classic amnesic syndrome or a deficit in striato-frontal working memory.

Equality of the psychological model underlying depressive symptoms in patients with temporal lobe epilepsy versus heterogeneous neurological disorders.

Controversy surrounds the question of whether there is a specific pattern of psychopathology or personality style observed in patients with temporal lobe epilepsy (TLE) or whether the symptoms of psychological distress reflect a common disorder such as depression. Measurement equivalence was examined to test the hypothesis that the latent variable model underlying scores on the Beck Depression Inventory (BDI) was equivalent across samples of patients with TLE (n = 187) and patients with heterogeneous neurological disorders (n = 150). A well-replicated model of depression or psychological distress comprising three related variables, negative attitude, performance difficulty, and somatic elements, displayed a pattern of strict metric invariance. This result suggests that the same set of latent variables is measured with the same metric relationship between item scores and latent variables in patients with TLE and in patients with heterogeneous neurological disorders.

Rule knowledge aids performance on spatial and object alternation tasks by alcoholic patients with and without Korsakoff's amnesia.

Delayed alternation (DA) and object alternation (OA) tasks traditionally have been used to measure defective response inhibition associated with dysfunction of frontal brain systems. However, these tasks are also sensitive to nonfrontal lesions, and cognitive processes such as the induction of rule-learning strategies also are needed in order to perform well on these tasks. Performance on DA and OA tasks was explored in 10 patients with alcohol-induced persisting amnestic disorder (Korsakoff’s syndrome), 11 abstinent long-term alcoholics, and 13 healthy non-alcoholic controls under each of two rule provision conditions: Alternation Rule and Correction Rule. Results confirmed that rule knowledge is a crucial cognitive component for solving problems such as DA and OA, and therefore, that errors on these tasks are not due to defective response inhibition alone. Further, rule-induction strategies were helpful to Korsakoff patients, despite their poorer performance on the tasks. These results stress the role of multiple cognitive abilities in successful performance on rule induction tasks. Evidence that these cognitive abilities are served by diffusely distributed neural networks should be considered when interpreting behavioral impairments on these tasks.

Equivalence of a measurement model of cognitive abilities in U.S. standardization and Australian neuroscience samples.

A psychological measurement model provides an explicit definition of (a) the theoretical and (b) the numerical relationships between observed scores and the latent variables that underlie the observed scores. Examination of the metric invariance of a measurement model involves testing the hypothesis that all components of the model relating observed scores to latent variables are equal across groups. The assumption of metric invariance is necessary for simple interpretation of scores. Establishing metric invariance also has implications for interpretation of convergent and divergent validity and patterns of deficit or disability. In this study the equivalence of the measurement model derived from the U.S. Wechsler Adult Intelligence Scale–III standardization sample was compared with a heterogeneous neurosciences sample in Australia. A pattern of strict metric invariance was observed across samples. These results provide evidence of the generality of the model underlying measurement of cognitive abilities.

Psychosocial and neuropsychological outcomes in two high-functioning males 20 years after traumatic brain injury

Abstract Researchers have emphasized a need for ongoing rehabilitation and support for individuals with traumatic brain injury FBI), yet there are few detailed descriptions of long-term outcome, and many people with long-standing TBI do not or cannot access support services. HB and NL, two men who sustained severe TBI, presented for neuropsychological consultation for the first time more than 20 years post-injury. Referral was prompted by significant mood and relationship disturbances, and ongoing mnemonic and cognitive symptoms. Structural imaging showed a very large lesion involving the orbitofrontal and dorsolateral regions of NLs left frontal lobe, while HB had a smaller lesion involving cortical and subcortical matter in the dorsolateral region of the left frontal lobe. Results from a range of neuropsychological tests indicated residual weakness in memory and variable impairments on two experimental tests of prefrontal working memory: Delayed Alternation and Object Alternation. The Minnesota Multiph...

Specificity of psychopathology in temporal lobe epilepsy

An investigation into the specificity of psychopathology in temporal lobe epilepsy was conducted using the Minnesota Multiphase Personality Inventory second edition (MMPI-2) profiles. Consecutive series of patients with left temporal lobe epilepsy (n = 49) and those with right temporal lobe epilepsy (n = 45) were compared with patients with other forms of epilepsy (n = 46) and other heterogeneous neurological conditions (n = 69). The investigation focused on the Clinical, Content, and Subscales scales that resembled descriptions of the Interictal Dysphoric Disorder symptoms and Temporal Lobe Epilepsy Personality Traits. Patients with right temporal lobe epilepsy and those with left temporal lobe epilepsy did not have different patterns of scale elevation, nor did they have clinical elevations compared with patients with other types of epilepsy or neurological controls. The MMPI-2 scales that resemble descriptions of the Interictal Dysphoric Disorder or Temporal Lobe Epilepsy Personality Syndrome were not elevated in either group of patients with temporal lobe epilepsy compared with the group of patients with non-temporal lobe epilepsy or heterogeneous neurological controls. This study adds to the mounting body of empirical research that has used standardized measures and matched groups, but failed to detect a special affinity between psychopathology and temporal lobe epilepsy.