The functional neuroanatomy of Tourette's syndrome: an FDG PET study III: functional coupling of regional cerebral metabolic rates.

Functional coupling of regional cerebral metabolic rates for glucose measured with [18F]-Fluoro-2-deoxy-D-glucose PET was compared in 18 drug-free patients with Tourette's Syndrome (TS) and 16 age- and sex-matched control subjects. Pearson product-moment correlation matrices containing correlations between metabolic rates in regions sampled throughout the brain were generated independently for TS patients and controls and compared. Significant differences between Z-transformed correlation coefficients were used to identify group differences, and revealed that the connectivity of the ventral striatum was most severely affected in TS. Changes in the coupling of other brain areas-primary motor areas, somatosensory association areas, and insula-also appeared to differentiate TS patients and controls. Evaluation of interrelationships between cortico-striato-thalamo-cortical circuits revealed the existence of functional connections between the motor and lateral orbitofrontal circuits in both groups, however, a reversal in the pattern of these interactions differentiated TS patients and controls. In controls, activity in these circuits appeared to be negatively correlated-i.e. increased activity in one is associated with relative inactivity the other. In TS patients, on the other hand, activity in the motor and lateral orbitofrontal circuits appears to be positively coupled. These results lend further credence to the hypothesis that altered limbic-motor interactions represent a pathophysiological hallmark of this disease.

A time course analysis of Stroop interference and facilitation: comparing normal individuals and individuals with schizophrenia.

Using randomized stimulus onset asynchrony (SOAs), the authors traced the time course of Stroop interference and facilitation in normal participants and participants with schizophrenia. Unlike earlier findings using blocked SOAs, singular peaks in interference, facilitation, or both occurred at particular SOAs. The peaks of normal participants and participants with schizophrenia differed. Findings are congruent with a model of Stroop performance that posits individual differences in processing speeds of target and nontarget stimulus dimensions, coupled with critical points in response selection. Participants with schizophrenia also showed more overall interference than normal control participants. A second experiment that added a temporal gap between the distractor word and target color obliterated Stroop effects only for individuals with schizophrenia. These findings provide a new empirical basis for models of Stroop effects. They are also consistent with hypotheses about the importance of the prefrontal cortex for working memory and prefrontal dysfunction in schizophrenia.

Stroop theory, memory, and prefrontal cortical functioning: reply to Cohen et al. (1997)

In this article, the authors respond to J. D. Cohen, K. O. Dunbar, D. M. Barch and T. S. Braver's (1997) comment on their target article. The present article (a) takes issue with the characterization given by Cohen et al. of the authors' approach as a classical speed-of-processing account of Stroop effects, (b) discusses the value and relevance of other theoretical concepts, such as traditional accounts of working memory and parallel distributed processing (PDP) approaches to Stroop effects, (c) further examines the possibility that the differences the authors observed in Experiment 2 between normal participants' performance and that of participants with schizophrenia may have been due to distractor stimulus degradation, particularly for participants with schizophrenia, and (d) argues for the relevance of the prefrontal cortex, as well as other brain areas, in accounting for their results. The authors conclude with a final theoretical question.

Social dysfunction and treatment failure in schizophrenia.

Recent evaluation of a 20-year-old experimental ward resocialization program for chronic schizophrenics indicates that the general level of activity, much of it social, was disruptive to the psychological functioning of patients, particularly sicker ones. Antipsychotic drugs positively affected psychological functioning and also decreased social behavior. A review of other studies indicates that we are not unique in finding that intensive socioenvironmental therapies have adverse effects on schizophrenics. Furthermore, a wide range of studies indicates that schizophrenics are prone to avoid social interaction and show a decrement in functioning as the intensity of such interactions increases. Unfortunately, although various hypotheses seem feasible, little is known about the reasons for schizophrenics' social dysfunction and little research is presently being done. Given the recent findings that neuroleptic drug treatment by itself is insufficient to keep many patients out of the hospital and that those that stay in the community show an increase in withdrawal, the development of successful treatment programs for schizophrenia may hinge upon our learning more about the nature of and reasons for the schizophrenic's social dysfunction.

Manual and saccadic reaction time with constant and variable preparatory intervals in schizophrenia.

Saccadic reaction time (RT) has been shown to be unimpaired in schizophrenia. Could this be due to its not requiring controlled information processing? The authors gave 49 schizophrenia patients and 34 controls manual and saccadic RT tasks with preparatory intervals of 1, 3, and 5 s given in regular and irregular sequences. If saccades require mainly automatic processes, they should not be affected by variations in the preparatory interval that are mediated by controlled processing. The manual task showed typical slower RT and larger preparatory interval effects in patients than in controls. Although the saccadic task showed significant effects of both the preparatory interval and the preparatory interval on the preceding trial similar in kind to those in manual RT, there were no group differences in these or in RT. The results are attributed to greater stimulus-response compatibility in the saccadic task, which puts fewer demands on working memory.

The reciprocal effects of leisure time activities and intellectual functioning in older people: a longitudinal analysis.

By using data from a representative longitudinal survey, the authors provide strong evidence that complex leisure time activities increase intellectual functioning for workers and nonworkers. Although the effects were relatively moderate, both the present article and its predecessor on the effects of paid work (C. Schooler. Mulatu, & Oates. 1999) showed that, even in old age, carrying out complex tasks has a positive effect on intellectual processes. In both cases, initially high levels of intellectual functioning led to high levels of environmental complexity, which in turn raised levels of intellectual functioning, thus providing a pathway contributing to the high correlation of intellectual functioning over a 20-year period in middle and late adulthood. The present findings indicate that even in old age carrying out substantively complex tasks builds the capacity to deal with the intellectual challenges such complex environments provide.

The continuing effects of substantively complex work on the intellectual functioning of older workers.

Using a nationally representative sample of employed men and women in this longitudinal study, the authors extended for another 20 years findings based on 1964 and 1974 data (Kohn & Schooler, 1983) that substantively complex work improves intellectual functioning. This study provides evidence that intellectual functioning and substantive complexity of work continue to reciprocally affect each other. In addition, it shows that the intellectual flexibility measure used earlier (Kohn & Schooler, 1978, 1983) is highly correlated with more standard measures of intellectual functioning. Most importantly, it shows that, although substantively complex work significantly increased the level of intellectual functioning of both the younger and older halves of the sample, the effect is significantly greater among the older workers.

Continued inhibitory capacity throughout adulthood: conceptual negative priming in younger and older adults.

Two negative priming experiments in older and younger adults are reported. Participants in Experiment 1, involving both positive and negative priming conditions, showed both types of priming. There were no significant differences between age groups. If anything, older participants showed more negative priming. In Experiment 2, involving only negative priming conditions, similar results were obtained. Our findings rule out possible effects of experimental conditions that episodic retrieval theorists have suggested might account for negative priming in older adults. Although our results may be consistent with an explanation of negative priming in older adults by an expansively specified theory of episodic retrieval, they are at least as consistent with the view that inhibitory processes are intact in older adults. In light of these findings, conflicting empirical results and alternative views of negative priming in older adults are examined.

Exploring a model of symbolic social communication: the case of 'magic' johnson.

We propose a model of symbolic social communication to explain the process whereby sociocultural identity mediates relationships among receivers, sources and messages to shape message effects. This exploratory study examines how two at-risk groups of African American men responded to various HIV prevention messages delivered by celebrity and professional sources. We interviewed 47 men from a homeless shelter and 50 male college students. Members of both groups were likely to select Johnson as the best person to deliver HIV prevention messages among a list of African American celebrity and professional sources. Results suggest the symbolic meanings embedded in celebrities and message topics are important and enduring influences on message effects. The images and ideas that a source represents are transferred to the advocated behavior, attitude or knowledge change and thus shape how messages are interpreted and received. Further understanding of how culture influences the effects of persuasive messages is critical for the improvement of health-communication campaigns.

Problem solving by reference to rules or previous episodes: the effects of organized training, analogical models, and subsequent complexity of experience.

Subjects learned a microcomputer drawing package under different conditions of training organization and practice complexity. Training instructions were presented in either a random or an organized order, and with or without an analogical model of the software package. Practice trial varied in visual and logical complexity. Performance on paper-and-pencil and problem-solving tests was better following the model than following the no-model condition when practice trials were logically complex; the reverse was true when they were logically simple. Performance on the test of problem solving was also better following organized training than following randomly ordered training when practice trials were visually complex; the reverse was true following visually simple practice. We propose that the subjects performed the tasks by engaging in either episode-based or rule-based processing, and that performance was optimized when the processing used at encoding and retrieval was the same. The acquisition of skill in solving real problems is explained as procedural compilation.

The effects of analogical training models and age on problem-solving in a new domain.

Young and middle-aged adults learned a microcomputer drawing package either with or without an analogical model of the package. Following training, problem-solving flexibility was assessed. Although no age differences were obtained following no-model training, middle-aged subjects performed worse than young subjects following model-based training. These results support the hypothesis that model-based training encourages elaboration and abstraction processes, and that older adults are less likely or less able to engage in such processing.

Age effects on analogy-based memory for text.

We examined age influences on analogy-based learning, in particular, analogy-based text memory. Adults (20-72 years) read pairs of passages describing analogous topics. We manipulated encoding complexity for the first passage and superficial topic similarity between passages, and assessed second-passage memory. Across all age groups, memory was better in the superficially similar topic condition only when encoding complexity had been simple. More critically, performance was better for similar topics only for the youngest adults. Younger adults performed worse than older adults in the dissimilar condition. Thus, only older adults identified and used the parallels between passages spontaneously.