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T S Woodward

Publications and source records attributed to T S Woodward.

10 recordsLinked to original sources
PubMed2005

Functional connectivity reveals load dependent neural systems underlying encoding and maintenance in verbal working memory.

One of the main challenges in working memory research has been to understand the degree of separation and overlap between the neural systems involved in encoding and maintenance. In the current study we used a variable load version of the Sternberg item recognition test (two, four, six, or eight letters) and a functional connectivity method based on constrained principal component analysis to extract load-dependent neural systems underlying encoding and maintenance, and to characterize their anatomical overlap and functional interaction. Based on the pattern of functional connectivity, constrained principal component analysis identified a load-dependent encoding system comprising bilateral occipital (Brodmann's area (BA) 17, 18), bilateral superior parietal (BA 7), bilateral dorsolateral prefrontal (BA 46), and dorsal anterior cingulate (BA 24, 32) regions. For maintenance, in contrast, constrained principal component analysis identified a system that was characterized by both load-dependent increases and decreases in activation. The structures in this system jointly activated by maintenance load involved left posterior parietal (BA 40), left inferior prefrontal (BA 44), left premotor and supplementary motor areas (BA 6), and dorsal cingulate regions (BA 24, 32), while the regions displaying maintenance-load-dependent activity decreases involved bilateral occipital (BA 17, 18), posterior cingulate (BA 23) and rostral anterior cingulate/orbitofrontal (BA 10, 11, 32) regions. The correlation between the encoding and maintenance systems was strong and negative (Pearson's r = -.55), indicting that some regions important for visual processing during encoding displayed reduced activity during maintenance, while subvocal rehearsal and phonological storage regions important for maintenance showed a reduction in activity during encoding. In summary, our analyses suggest that separable and complementary subsystems underlie encoding and maintenance in verbal working memory, and they demonstrate how constrained principal component analysis can be employed to characterize neuronal systems and their functional contributions to higher-level cognition.

Adolescent↗
PubMed2003

Source monitoring and memory confidence in schizophrenia.

BACKGROUND: The present study attempted to extend previous research on source monitoring deficits in schizophrenia. We hypothesized that patients would show a bias to attribute self-generated words to an external source. Furthermore, it was expected that schizophrenic patients would be overconfident regarding false memory attributions. METHOD: Thirty schizophrenic and 21 healthy participants were instructed to provide a semantic association for 20 words. Subsequently, a list was read containing experimenter- and self-generated words as well as new words. The subject was required to identify each item as old/new, name the source. and state the degree of confidence for the source attribution. RESULTS: Schizophrenic patients displayed a significantly increased number of source attribution errors and were significantly more confident than controls that a false source attribution response was true. The latter bias was ameliorated by higher doses of neuroleptics. CONCLUSIONS: It is inferred that a core cognitive deficit underlying schizophrenia is a failure to distinguish false from true mnestic contents.

Adult↗
PubMed2002

Relationship between neuroleptic dosage and subjective cognitive dysfunction in schizophrenic patients treated with either conventional or atypical neuroleptic medication.

Previous research has suggested that high doses of conventional neuroleptics may induce neurocognitive deficits when assessed with standard tasks. However, little is known about the effects of high doses of neuroleptics (conventional or atypical) on subjective cognitive dysfunction. Recent research stresses the putative importance of self-reported cognitive deficits for both symptomatic outcome and medication compliance. The aim of the present study was to investigate the impact of neuroleptic medication on subjective cognition in patients treated with either conventional or atypical agents (clozapine, risperidone, olanzapine). Patients were asked to endorse the items of a questionnaire entitled 'Subjective Well-Being under Neuroleptic Treatment' prior to discharge. Subjective impairment, as assessed with the subscale 'mental functioning', was significantly correlated with greater conventional neuroleptic dosage after controlling for psychopathology (P<0.05). The difference between patients medicated with higher doses of conventional neuroleptics and those with lower doses was highly significant (P<0.001). In contrast, higher atypical neuroleptic doses were not associated with impairment.

Adult↗
PubMed2001

Base rates of WAIS-R VIQ-PIQ differences in 1593 psychiatric inpatients.

The purpose of this study was to provide the psychologist with base-rate tables for the Wechsler Adult Intelligence Scale-Revised (WAIS-R) Verbal IQ-Performance IQ difference scores in 1593 psychiatric inpatients. Subtables also were provided for each of three primary psychiatric diagnoses (schizophrenia spectrum disorders, bipolar disorders, and depression). The base rates of VIQ-PIQ splits in the full inpatient sample, and those for the subsamples based on primary psychiatric diagnosis, were very similar to those reported in the WAIS-R standardization sample. Consistent with past research on the standardization sample, the VIQ-PIQ split was correlated positively with Full Scale IQ (FSIQ), indicating that larger splits are more common at the higher IQ levels. Therefore, base-rate tables also were provided for the total inpatient sample split into five IQ groupings.

Adult↗
PubMed2001

The role of the anterior cingulate cortex in conflict processing: evidence from reverse stroop interference.

A recent theoretical account delineated the role of the anterior cingulate cortex (ACC) in cognitive control as the detection of conflict between competing information streams. Using functional magnetic resonance imaging, we examined the activity of this brain structure during different forms and degrees of conflict between the word and the color dimensions of Stroop stimuli. Overall, our results showed a dissociation between the degree of conflict and ACC activation. More specifically, although ACC activation was very extensive when print color interfered with word reading performance, the level of conflict, as measured by reaction time costs, was only moderate compared to other conditions. These results suggest that either the ACC is differentially sensitive to various types of conflict or its function should be extended to include other cognitive constructs, such as resolution of prior inhibition.

Adult↗
PubMed2001

Measuring adaptive behavior in inpatient neuropsychiatry: the Behavioural Assessment Scale.

The Behavioural Assessment Scale (BAS) was administered to a sample of 95 inpatients with neuropsychiatric conditions. The total scores in the sample ranged from 26 to 145 (maximum possible score is 163), without any evidence of the "floor effect" encountered with other tests used with this population. Investigation into the psychometric structure of the BAS revealed three factors interpreted as Daily Living Skills, Communication/Social Skills, and Problem Behavior. The high intercorrelation between the two dominant factors was interpreted as general sensitivity of the BAS to global decline in functioning associated with severity of illness. These results confirm a previous psychometric investigation carried out on an elderly psychiatric sample. A recommendation is made for interpreting subscales based on these factor domains when specific abilities are of interest and using a Global Functioning subscale as a measure of overall adaptive behavior for both adult and geriatric inpatient neuropsychiatry patients.

Activities of Daily Living↗
PubMed2000

Internal consistency and concurrent validity of two short forms of the Visual Form Discrimination Test.

The purpose of this study was to evaluate the reliability and concurrent validity of 2 short forms of the Visual Form Discrimination Test, referred to as first half (FH) and front-back (FB). Participants were a mixed sample of 225 patients seen for neuropsychological evaluations. The mean difference score between both short forms and the full form was less than 1 point. The short-total correlations were .85 and .86 for the FH and FB forms, respectively. A binary clinical decision rule, used to classify patients as normal or impaired, resulted in a 93.3% correct and a 94.7% correct classification rate for the FH and FB forms, respectively. It is concluded that the short form of the test, used in conjunction with a clinical decision rule, results in a very minor loss of accuracy.

Adult↗
PubMed2000

The Behavioural Assessment Scale: norms for factor-based subscales.

The Behavioural Assessment Scale (BAS) was developed to assess adaptive functioning in older persons with severe cognitive impairment. Previous research has demonstrated that BAS items can be rescored as 3 factor-based subscales entitled Daily Living Skills, Communication and Social Skills, and Problem Behavior, or as a global functioning aggregate. Normative information on these subscales is most helpful when based on a severely impaired sample because very little variation is present in an unimpaired population. In accordance with this goal, regression-predicted age- and mental-status-corrected percentile ranks are presented for these 4 subscales, and for the total score of the BAS.

Activities of Daily Living↗
PubMed1999

The Behavioural Assessment Scale: internal consistency and factor structure for an elderly psychiatric population.

The subscales of the Behavioural Assessment Scale (BAS) (Language, Mobility, Physical Independence, Occupation and Orientation, and Social Integration) were designed to measure specific areas of functioning. The purpose of this investigation was to assess the psychometric structure of the BAS in a sample of 275 geriatric psychiatry inpatients. This psychometric assessment was carried out using 2 methods: measures of internal consistency and exploratory factor analysis. The measures of internal consistency suggested that only the Language and Physical Independence subscales measured a unified construct. The subsequent factor analysis revealed 3 highly correlated factors that accounted for 65% of the item variance. These factors were interpreted as Daily Living Skills, Communication/Social Skills, and Problem Behavior. The high intercorrelations between the factors were interpreted as a general sensitivity of the BAS to global decline in functioning associated with dementia (i.e., severity of illness). The computation of factor-based subscales and a general functioning aggregate were recommended for clinical use of the BAS.

Activities of Daily Living↗