Psychomotor symptoms of schizophrenia map on the cerebral motor circuit

Schizophrenia is a devastating disorder thought to result mainly from cerebral pathology. Neuroimaging studies have provided a wealth of findings of brain dysfunction in schizophrenia. However, we are still far from understanding how particular symptoms can result from aberrant brain function. In this context, the high prevalence of motor symptoms in schizophrenia such as catatonia, neurological soft signs, parkinsonism, and abnormal involuntary movements is of particular interest. Here, the neuroimaging correlates of these motor symptoms are reviewed. For all investigated motor symptoms, neural correlates were found within the cerebral motor system. However, only a limited set of results exists for hypokinesia and neurological soft signs, while catatonia, abnormal involuntary movements and parkinsonian signs still remain understudied with neuroimaging methods. Soft signs have been associated with altered brain structure and function in cortical premotor and motor areas as well as cerebellum and thalamus. Hypokinesia is suggested to result from insufficient interaction of thalamocortical loops within the motor system. Future studies are needed to address the neural correlates of motor abnormalities in prodromal states, changes during the course of the illness, and the specific pathophysiology of catatonia, dyskinesia and parkinsonism in schizophrenia.

After-effects and after-effects and after-effects of after-effects: The multiple side effects of prospective memory

In a prospective memory task responding to a prospective memory target involves switching between ongoing and prospective memory task which can result in a slowing of subsequent ongoing task performance (i.e., an after-effect). Moreover, a slowing can also occur when prospective memory targets occur after the prospective memory task is deactivated (i.e., another after-effect). In this study, we investigated both after-effects within the same study. Moreover, we also tested whether the latter after-effects even occur on subsequent ongoing task trials. The results show, in fact, after-effects of all kinds. Thus, (1) correctly responding to prospective memory targets results in after-effects, a so far neglected cost on ongoing task performance, (2) responding to deactivated prospective memory targets also slows down performance, probably due to the involuntary retrieval of the intention, and (3) this slowing is present even on subsequent ongoing task trials, suggesting that even deactivated intentions are sufficient to induce a conflict that requires subsequent adaptation. Overall, these results indicate that performance slowing in a prospective memory experiment includes various kinds of sources, not only monitoring cost, and these sources may be understood best in terms of conflict adaptation.

Increased Resting State Network Connectivity in Synesthesia: Evidence for a Neural Basis of Synesthetic Consistency

Studying individual differences in conscious awareness can potentially lend fundamental insights into the neural bases of binding mechanisms and consciousness (Cohen Kadosh and Henik, 2007). Partly for this reason, considerable attention has been devoted to the neural mechanisms underlying grapheme–color synesthesia, a healthy condition involving atypical brain activation and the concurrent experience of color photisms in response to letters, numbers, and words. For instance, the letter C printed in black on a white background may elicit a yellow color photism that is perceived to be spatially colocalized with the inducing stimulus or internally in the “mind's eye” as, for instance, a visual image. Synesthetic experiences are involuntary, idiosyncratic, and consistent over time (Rouw et al., 2011). To date, neuroimaging research on synesthesia has focused on brain areas activated during the experience of synesthesia and associated structural brain differences. However, activity patterns of the synesthetic brain at rest remain largely unexplored. Moreover, the neural correlates of synesthetic consistency, the hallmark characteristic of synesthesia, remain elusive.