Configural errors on WISC-III block design

This study describes two experiments undertaken to explore the clinical significance and cognitive substrates of Block Design broken configurations in children. Broken configurations were defined as instances in which the child placed a block outside the 2 x 2 or 3 x 3 square matrix. In Experiment 1, 336 normal children between the ages of 6 and 14 were administered WISC-III Block Design. Broken configurations were fairly common, but almost always self-corrected. The tendency to break configurations was inversely related to overall Block Design performance and mother's level of education, and directly related to the perceptual cohesiveness of the design. In Experiment 2, children were administered WISC-III Block Design and a global-local similarity judgment task. The frequency of broken configurations was inversely related to global perceptual bias. Taken together, the results of these experiments indicate that while broken configurations are common, particularly on designs with high perceptual cohesiveness, a high number of broken configurations or final answers containing broken configuration are associated with weaker visuospatial skills. Broken configurations are also made more frequently by children whose perception is less influenced by the global properties of spatial stimuli.

Internal consistency, temporal stability and neuropsychological correlates of three cognitive components of the Positive and Negative Syndrome Scale (PANSS)

Comprehensive models of schizophrenia have increasingly included symptoms of cognitive dysfunction as an important feature of schizophrenia. Factor analytic studies of the Positive and Negative Syndrome Scale (PANSS) have consistently established cognitively disorganized symptoms as a separate domain from positive and negative symptoms. However, the individual symptom composition of the cognitive domain varies from model to model. The present study explores the temporal stability, internal consistency, concurrent validity, and discriminant validity for three published PANSS factor analytically derived cognitive components (Bell et al., 1994a, Psychiatry Res., 52, 295-303; Dollfus et al., 1991. Eur. Psychiatry, 6, 251-259; Kay and Sevy, 1990. Schizophr. Bull., 16, 537-544). Analyses were conducted using PANSS data from 120 patients with DSM-IV diagnoses of schizophrenia or schizoaffective disorder. Results indicate that the Bell et al. and Kay and Sevy models have similar psychometric properties including adequate temporal stability, internal consistency, and discriminant validity. The Kay model demonstrated somewhat better concurrent validity with cognitive test measures, while the Dollfus model demonstrated relatively poor psychometrics. The symptom composition of a narrowly defined cognitively disorganized subtype and a more broadly defined cognitively impaired subtype are discussed in terms of their value for schizophrenia research.

Clock tests in depression, Alzheimer's disease, and elderly controls

OBJECTIVE

While clock-drawing tests are commonly used to screen for cognitive impairment in the elderly, little is known about the performance of elderly depressives.

METHODS

We compared thirty-three patients with major depression to forty-two Alzheimer's disease and thirty age-matched controls on clock-drawing, copying, and reading.

RESULTS

Patients with Alzheimer's disease had significantly lower scores on clock-drawing, copying, and reading than patients with depression or the controls (p < 0.05). Patients with depression did not differ significantly from controls on quantitative scores or qualitative errors.

CONCLUSIONS

Clock tests may be useful for identifying depressed patients with underlying dementia.

The dynamics of primate M retinal ganglion cells

The retinal ganglion cells (RGCs) of the primate form at least two classes--M and P--that differ fundamentally in their functional properties. M cells have temporal-frequency response characteristics distinct from P cells (Benardete et al., 1992; Lee et al., 1994). In this paper, we elaborate on the temporal-frequency responses of M cells and focus in detail on the contrast gain control (Shapley & Victor, 1979a,b). Earlier data showed that the temporal-frequency response of M cells is altered by the level of stimulus contrast (Benardete et al., 1992). Higher contrast shifts the peak of the frequency-response curve to higher temporal frequency and produces a phase advance. In this paper, by fitting the data to a linear filter model, the effect of contrast on the temporal-frequency response is subsumed into a change in a single parameter in the model. Furthermore, the model fits are used to predict the response of M cells to steps of contrast, and these predictions demonstrate the dynamic effect of contrast on the M cells' response. We also present new data concerning the spatial organization of the contrast gain control in the primate and show that the signal that controls the contrast gain must come from a broadly distributed network of small subunits in the surround of the M-cell receptive field.

Information Multiple Choice among healthy older adults: characteristics, correlates, and clinical implications

Information Multiple Choice (WAIS-R-NI, Kaplan et al., 1991), may be valuable when used in conjunction with the standard Information subtest. Due to the reduced retrieval demands posed by its recognition format, scores should be even less susceptible to neuropathology or normal aging than are those on the standard (recall) test, facilitating assessment of premorbid attainment in individuals suffering from retrieval-related memory deficits. We provide reliability, validity, and normative data on Information Multiple Choice from a sample (N = 177) of healthy adults aged 50 - 90 years. Information Multiple Choice correlates strongly with the standard Information subtest (r = .81) and, as predicted and unlike the standard test, does not decline even in very old age. The construct validity of Information Multiple Choice is supported, and its clinical utility will be enhanced by these normative data.

Personality and psychopathology in schizophrenia: the association between personality traits and symptoms

Research has indicated that stable individual differences in personality exist among persons with schizophrenia, and that they likely predate the onset of illness. Little is known, however, about whether individual differences in personality are related to levels of psychopathology. This study tested the hypotheses that levels of Extroversion, Neuroticism, and Psychoticism are associated with symptomatology. Accordingly, measures of these dimensions of personality and of symptomatology were obtained simultaneously for 113 male subjects with schizophrenia or schizoaffective disorder. Next, subjects were characterized as having high or low levels on each personality dimension and their scores on the five components of the Positive Negative Syndrome Scale were compared using multivariate and univariate procedures. Results indicate that extroverted subjects had lower levels of Positive, Negative, and Emotional Discomfort symptoms, and higher levels of Excitement symptoms than introverted subjects. Subjects with higher levels of Neuroticism had higher levels of Positive and Emotional Discomfort symptoms than subjects with lower levels of Neuroticism. No differences in symptoms were found among subjects with higher versus lower levels of Psychoticism. Results suggest individual differences in personality are associated with psychopathology in schizophrenia and may help further explain the heterogeneity widely observed in this disorder.

emm typing and validation of provisional M types for group A streptococci

This report discusses the following issues related to typing of group A streptococci (GAS): The development and use of the 5' emm variable region sequencing (emm typing) in relation to the existing serologic typing system; the designation of emm types in relation to M types; a system for validation of new emm types; criteria for validation of provisional M types to new M-types; a list of reference type cultures for each of the M-type or emm-type strains of GAS; the results of the first culture exchange program for a quality control testing system among the national and World Health Organization collaborating centers for streptococci; and dissemination of new approaches to typing of GAS to the international streptococcal community.

The use of clock tests in schizophrenia

Though clock drawing tests are well recognized as measures of cognitive function, there is little data on the performance of patients with schizophrenia. We compared 24 patients with schizophrenia to 24 healthy, age-matched controls on clock drawing, copying, and reading. Patients with schizophrenia performed significantly worse on clock drawing and copying despite the fact that the groups had similar scores on the MMSE. Worse performance was associated with higher scores on the BPRS. Clock drawing and copying may be useful for the assessment of cognition in schizophrenia, and the monitoring of cognitive changes associated with antipsychotic medication.

The functional consequences of memory impairments on initial work performance in people with schizophrenia

Exploring the link between cognitive impairments and domains of function is a new trend in schizophrenia research. This study reports on the association of verbal memory impairment and initial work function for a group of 87 individuals diagnosed with either schizophrenia or schizoaffective disorder. Multiple regression analyses were used to predict the degree of association between verbal memory variables and ratings on the Work Behavior Inventory (WBI) in the initial week of a vocational rehabilitation program. Results indicated that verbal memory scores predicted 20% of the WBI total score. Results also indicated strong relationships with the individual work domains of work habits and work quality and weaker relationships with the domains of cooperativeness and personal presentation. No significant relationship was found between verbal memory variables and social skills at the job site. Verbal memory impairment is discussed as a rate limiting factor in rehabilitation.

Personality and psychosocial dysfunction in schizophrenia: the association of extraversion and neuroticism to deficits in work performance

Research on vocational dysfunction in schizophrenia has as yet only examined associated features of illness. We hypothesized that personality variables may be also associated with work function. We reasoned that higher levels of extraversion and neuroticism would predict poor function by virtue of the social support seeking and passive/avoidant coping styles associated with each. To test this, multiple regressions were conducted in which measures of extraversion and neuroticism predicted work performance among 43 subjects with schizophrenia or schizoaffective disorder. Higher levels of extraversion and neuroticism significantly predicted poorer function, accounting for between 7% and 27% of the variance in global cooperativeness, work quality, work habits and personal presentation measures of work behavior. The potential importance of assessing personality in rehabilitation is discussed.

Representation of spatial frequency and orientation in the visual cortex

Knowledge of the response of the primary visual cortex to the various spatial frequencies and orientations in the visual scene should help us understand the principles by which the brain recognizes patterns. Current information about the cortical layout of spatial frequency response is still incomplete because of difficulties in recording and interpreting adequate data. Here, we report results from a study of the cat primary visual cortex in which we employed a new image-analysis method that allows improved separation of signal from noise and that we used to examine the neurooptical response of the primary visual cortex to drifting sine gratings over a range of orientations and spatial frequencies. We found that (i) the optical responses to all orientations and spatial frequencies were well approximated by weighted sums of only two pairs of basis pictures, one pair for orientation and a different pair for spatial frequency; (ii) the weightings of the two pictures in each pair were approximately in quadrature (1/4 cycle apart); and (iii) our spatial frequency data revealed a cortical map that continuously assigns different optimal spatial frequency responses to different cortical locations over the entire spatial frequency range.

On the nature and pattern of neurocognitive function in major depressive disorder

An effect size analysis of neurocognitive function in patients with major depressive disorder using meta-analytic principles was conducted. The results from 726 patients with depression and 795 healthy normal controls revealed that depression had the largest effect on measures of encoding and retrieval from episodic memory. Intermediate effect sizes were recorded on tests of psychomotor speed and tests that require sustained attention. Minimal effect sizes were found on tests of semantic memory, primary memory, and working memory. Moreover, major depressive disorder is accompanied by dysfunction of effortful encoding of information along with an accompanying inefficiency of retrieving poorly encoded information from declarative memory.

Insight and interpersonal function in schizophrenia

Research has linked impaired insight in schizophrenia to poorer medication compliance and treatment outcome. It is unclear, however, whether poorer interpersonal function is also associated with impaired insight. To examine this question, subjects with schizophrenia or schizoaffective disorder were classified as having unimpaired (N = 44) or impaired (N = 57) insight, and their scores on Heinrichs et al.'s Quality of Life (QOL) Scale were compared. Multiple regressions were conducted to determine the relationship between individual components and social function. Results indicate that subjects with impaired insight had significantly poorer QOL interpersonal relation and intrapsychic foundation scores than unimpaired subjects, despite having equivalent deficit symptoms. Unawareness of the social consequences of illness was found to be the component of insight more closely linked to social dysfunction. This suggests that impairments in insight may be uniquely associated with social dysfunction.

A mathematical model of HIV transmission in NSW prisons

A mathematical model was developed to estimate HIV incidence in NSW prisons. Data included: duration of imprisonment; number of inmates using each needle; lower and higher number of shared injections per IDU per week; proportion of IDUs using bleach; efficacy of bleach; HIV prevalence and probability of infection. HIV prevalence in IDUs in prison was estimated to have risen from 0.8 to 6.7% (12.2%) over 180 weeks when using lower (and higher) values for frequency of shared injections. The estimated minimum (and maximum) number of IDU inmates, infected with HIV in NSW prisons was 38 (and 152) in 1993 according to the model. These figures require confirmation by seroincidence studies.

The maintained discharge of neurons in the cat lateral geniculate nucleus: spectral analysis and computational modeling

The maintained discharge of neurons along the early visual pathway in mammals constitutes the "noise" from which the visual signal must be discriminated. The statistics of this background noise in cat retinal ganglion cells (RGCs) have been shown to conform to that of a gamma-distributed renewal process (Kuffler et al., 1957; Barlow & Levick, 1969), and power spectrum analysis reveals that this property allows for low noise levels at the temporal-frequency range (0-10 Hz) most important for visual performance (Troy & Robson, 1992). In this study, we compare the statistics of the maintained discharge of cat lateral geniculate neurons with those of its RGC input by simultaneous recordings of spikes and S-potentials in single relay cells of the cat lateral geniculate nucleus (LGN). We demonstrate that, during primarily tonic spiking activity, the LGN maintained discharge preserves the renewal process statistics of its RGC input and also generates relatively little noise at the temporal frequencies important for vision. However, during burst spiking activity, the renewal process model breaks down and increased noise is generated at 2-10 Hz. This suggests that optimization of the visual signal/noise ratio is not a prime consideration in the behavioral states associated with bursting activity in the LGN. The occurrence of burst spikes in LGN relay cells is dependent on the activity of T-type calcium channels in their plasma membranes (Jahnsen & Llinas, 1984a,b). We show that a computational model of LGN relay cells that incorporates T-channel kinetics (Mukherjee & Kaplan, 1995) can correctly simulate LGN maintained discharge statistics during both tonic and bursty firing conditions, and indicates an essential role for this ion channel in determining the dynamic noise properties of the LGN. We also use the computational model to predict how the burstiness of the LGN maintained discharge is affected by the statistics of its RGC input.

Neurocognitive function and insight in schizophrenia: support for an association with impairments in executive function but not with impairments in global function

It remains unclear how impaired insight and neurocognitive impairment are related to one another in schizophrenia. In order to examine this relationship, subjects with schizophrenia or schizoaffective disorder were classified as having 'impaired' (n=38) or 'unimpaired' (n=43) insight based on their insight rating on the Positive and Negative Syndrome Scale (PANSS). Their performance on neuropsychological tests of global function, executive function, memory and vigilance was then compared. Multivariate analyses followed by Scheffe tests indicated that subjects with impaired insight performed less well on the Wisconsin Card Sorting Test, demonstrating poorer abstract flexibility and heightened perseveration. No differences were found between the groups with regard to global cognitive function, memory or vigilance. This suggests that insight is closely linked to deficits in executive function, and that it may be associated with the compromise of frontal lobe function.

Affect recognition in deficit syndrome schizophrenia

This study has three aims: (1) to compare a deficit syndrome schizophrenia sample (n=19) with a non-deficit sample (n=50) on affect recognition; (2) to determine the association between individual deficit criteria and affect recognition performance in the deficit sample; and (3) to compare the deficit syndrome and negative syndrome samples with respect to affect recognition test performance. Results revealed that the deficit sample had significantly lower adjusted mean affect recognition scores than the non-deficit sample. In addition, 17 of the 19 subjects with deficit syndrome had impairments in affect recognition, whereas, non-deficit subjects were only slightly more likely to score in the impaired range than the unimpaired range. Within the deficit sample Diminished Sense of Purpose was the criterion most strongly associated with affect recognition impairment. Finally, a group of subjects classified as having prominent negative symptoms did not demonstrate the same pattern of impairment as shown by the deficit syndrome sample. The relationship between affect recognition, information processing and the deficit syndrome is discussed along with implications for classification in schizophrenia.