Cognition in schizophrenia: core psychological and neural mechanisms

The challenge in understanding cognitive impairment in schizophrenia is that people with this illness have deficits in an array of domains. Here, we briefly review evidence regarding the pattern of deficits within three domains: context processing, working memory and episodic memory. We suggest that there may be a common mechanism driving deficits in these domains - an impairment in the ability to actively represent goal information in working memory to guide behavior, a function we refer to as proactive control. We suggest that such deficits in proactive control reflect impairments in dorsolateral prefrontal cortex, its interactions with other brain regions, such as parietal cortex, thalamus and striatum, and the influence of neurotransmitter systems, such as dopamine, GABA and glutamate.     

Insights for treatment in Tourette syndrome from fMRI

In a recent American Journal of Psychiatry article, Wang and colleagues used functional MRI (fMRI) to examine cortico-striatal-thalamo-cortical circuitry in Tourette syndrome (TS), advancing the field's investigation of circuit level dysfunction in vivo in individuals with TS. Their results provide insight for interrogating neural mechanisms underlying different treatment methods.     

Classification accuracy and consistency of computerized adaptive testing

In this article, four item selection methods in computerized adaptive testing are examined in terms of classification accuracy and consistency, including two popular heuristics for constraint management, the maximum priority index (MPI) method and the weighted deviation modeling method, as well as the widely known maximum Fisher information method and randomized item selection as baselines. Results suggest that the MPI method is able to meet constraints and keep test overlap rate low. Among the four methods, it is the only one that manages to produce parallel forms in terms of content coverage and, consequently, the only method to which the idea of classification consistency applies. With tests as short as 12 items, the MPI method does fairly well in classifying examinees accurately and consistently. Its performance improves with longer tests. The effects of number of decision categories and cut score locations are also examined. Recommendations are made in the Discussion section.     

Candy and the brain: neural response to candy gains and losses

Incentive processing is a critical component of a host of cognitive processes, including attention, motivation, and learning. Neuroimaging studies have clarified the neural systems underlying processing of primary and secondary rewards in adults. However, current reward paradigms have hindered comparisons across these reward types as well as between age groups. To address methodological issues regarding the timing of incentive delivery (during scan vs. postscan) and the age-appropriateness of the incentive type, we utilized fMRI and a modified version of a card-guessing game (CGG), in which candy pieces delivered postscan served as the reinforcer, to investigate neural responses to incentives. Healthy young adults 22–26 years of age won and lost large and small amounts of candy on the basis of their ability to guess the number on a mystery card. BOLD activity was compared following candy gain (large/small), loss (large/small), and neutral feedback. During candy gains, adults recruited regions typically involved in response to monetary and other rewards, such as the caudate, putamen, and orbitofrontal cortex. During losses, they displayed greater deactivation in the hippocampus than in response to neutral and gain feedback. Additionally, individual-difference analyses suggested a negative relationship between reward sensitivity (assessed by the Behavioral Inhibition/Behavioral Activation Scales) and the difference between high- and low-magnitude losses in the caudate and lateral orbitofrontal cortex. Also within the striatum, greater punishment sensitivity was positively related to the difference in activity following high as compared to low gains. Overall, these results show strong overlap with those from previous monetary versions of the CGG and provide a baseline for future work with developmental populations.     

Social and affective impairments are important recovery after acquired stroke in childhood

Despite a congenital stroke, overall intelligence at school age is generally within the normal range. Language acquisition problems are more prominent when children are younger (<5 years of age) than when they are older. They are present after both right and left lesions, but appear to have different features. They are less apparent than in the child with a developmental language disorder. Acquired aphasia in childhood results in subtle and often persisting deficits. Children with congenital strokes are at risk for behavioral and psychiatric problems. Those with congenital right hemisphere strokes appear to be more difficult infants, but there is no clear side of lesion effect in older children. Children with congenital right hemisphere strokes have more prominent spatial difficulties than their left lesion counterparts. Evaluating both the process and the product highlights this. Increasing the difficulty of the task often brings out deficits in the right lesion group even when they seemingly recovered.     

The effect of age on rule-based category learning

An explicit, rule-based, category-learning task with abstract visual stimuli was administered to 50 healthy older adults and 48 younger adults. Accuracy and reaction time (RT) were examined for the effects of age, perceptual abilities, rule memory, rule complexity, stimulus novelty, and response competition. Older adults performed at equivalent levels to younger adults when applying a simple rule, but showed performance decrements when applying a more complex rule. The age effect interacted with both stimulus novelty and response competition, and was not eliminated after controlling for basic perceptual abilities and rule memory. The authors suggest that older adults show category learning deficits in conditions that require enhanced cognitive control. These results are discussed in reference to the growing body of literature regarding age-related change in executive abilities and frontal lobe function.     

Extracting core components of cognitive control

The facility with which humans perform and shift among a wide variety of cognitive tasks seems to indicate a mechanism for entering into a task-dependent mode or set. However, little is known about the neural systems that subserve task control. A recent neuroimaging study by Dosenbach et al. offers a set of novel methodological tools to examine this issue and uncovers new candidate brain regions for a core system that might implement task sets.     

Affective reactivity in language: the role of psychophysiological arousal

Several studies have found that individuals with schizophrenia and their relatives, as well as healthy controls, exhibit greater language disturbance when discussing affectively negative as compared to positive or neutral topics. The goal of this study was to test the hypothesis that negative emotion impairs language production, at least in part by increasing physiological arousal. The authors had 35 healthy adults produce speech in response to affectively negative, positive, and neutral questions while the authors recorded heart rate and skin conductance. Participants displayed greater amounts of reference errors, higher heart rates, and a higher frequency of nonspecific skin conductance responses when discussing affectively negative as compared to positive or neutral topics.     

Contrasting effects of self-schema priming on lexical decisions and interpersonal stroop task performance: evidence for a cognitive/interactionist model of interpersonal dependency

Four experiments tested a key tenet of Bornstein's (1992, 1993) cognitive/interactionist (C/I) model of interpersonal dependency: that priming the helpless self-schema (HSS) alters processing of dependency-related information in dependent--but not nondependent--individuals. Experiments 1 and 2 assessed the effects of subliminal lexical priming and an emotional priming manipulation on lexical decision (LD) judgments for dependency-related words and control words. Experiments 3 and 4 assessed the effects of these same priming procedures on Interpersonal Stroop Task (IST) performance. As predicted, priming the HSS produced contrasting effects on different outcome measures, decreasing LD latencies, but increasing IST response times. Results are discussed in the context of the C/I model, and suggestions for future studies are offered.