Biomedical subjects

W Perlstein

Publications and source records attributed to W Perlstein.

3 recordsLinked to original sources

PubMed1999

Increased stroop facilitation effects in schizophrenia are not due to increased automatic spreading activation.

Studies using the single trial Stroop task consistently reveal increased reaction time (RT) facilitation effects among schizophrenia patients. One possible mechanism underlying this effect is increased automatic spreading activation in semantic networks. The current study was designed to test this hypothesis. We administered the Stroop task and two semantic priming tasks to the same subjects. Patients showed greater Stroop RT facilitation than controls, no evidence of increased semantic priming at short stimulus onset asynchronies (SOAs), and reduced semantic priming at long SOAs. In addition, abnormal Stroop performance was related to the severity of Disorganization symptoms. These results are inconsistent with the spreading activation hypothesis. Alternative hypotheses regarding the source of Stroop task performance deficits in schizophrenia are discussed.

Adult↗

PubMed1998

Functional hypofrontality and working memory dysfunction in schizophrenia.

OBJECTIVE: Hypofrontality is a common but not invariable finding in schizophrenia. Inconsistencies in the literature may reflect, in part, the fact that abnormal physiological responses in the prefrontal cortex are best identified under conditions that place well-specified functional demands on this region. METHOD: The authors studied eight patients with schizophrenia and eight matched comparison subjects using [(15)O]H2O positron emission tomography and the "N-back" task, which activates the prefrontal cortex as a function of working memory load in normal subjects. RESULTS: Under low-working-memory-load conditions, the accuracy of both groups in the N-back task was equal, but when the memory load increased, the patients' performance deteriorated more than did that of the comparison subjects. The regional cerebral blood flow response to increased working memory load was significantly reduced in the patients' right dorsolateral prefrontal cortex. CONCLUSIONS: These results confirm the importance of using tasks that tap specific cognitive functions, linked to specific neural systems, in studies of brain-behavior relationships in schizophrenia. Hypofrontality is reliably demonstrated in schizophrenia during tasks that engage working memory functions of the prefrontal cortex.

Functional Laterality↗

PubMed1990

Sensation-seeking: electrodermal and behavioral effects of stimulus content and intensity.

Although a number of studies support an arousal theory interpretation of differential sensation-seeking behavior, the conditions under which arousal correlates of this personality dimension are manifest is as yet unclear. Both theory and research suggest that among the external factors affecting the differential arousal response are stimulus relevance and stimulus intensity. The present study assessed the impact of these factors on both psychophysiological and behavioral responses. Subjects were preselected to represent the extremes of the sensation-seeking dimension, then exposed to auditory and visual presentations of a series of sexual and aggressive stimuli of systematically varied intensity. High sensation seekers gave larger amplitude SCRs to violent stimuli and larger initial responses to sexual stimuli presented visually, while verbal response intensities showed an opposite pattern. Overall, results provided support for an arousal theory interpretation of sensation-seeking, but suggested that the probability and magnitude of group differences is a somewhat complex function of stimulus intensity, stimulus modality, and perhaps other factors not yet assessed.

Adult↗