Biomedical subjects

Torsten Wüstenberg

Publications and source records attributed to Torsten Wüstenberg.

9 recordsLinked to original sources

PubMed2006

Common modules for processing invalidly cued events in the human cortex.

A central question regarding the nature of cognitive control is the extent to which different tasks are controlled by a common system. We addressed this issue by comparing the cortical activation associated with the processing of an invalidly cued event with the activation associated with a validly cued event. In a perceptual cueing task, we cued the likely stimulus modality (visual or auditory), and in a motor cueing task, we cued the likely motor response (left or right hand). Event-related functional MRI revealed increased activation in the anterior cingulate cortex on valid and invalid trials in both tasks. In addition, a network of six regions, including the dorsal medial frontal cortex, showed increased activation on invalid trials irrespective of whether the invalid cue referred to the stimulus modality or response. Findings suggest that dorsal medial frontal cortex rather than the anterior cingulated cortex is involved in conflict monitoring operations. We summarize our findings in a model that links six modules for processing invalidly cued events.

Acoustic Stimulation↗

PubMed2006

Dysfunction of ventral striatal reward prediction in schizophrenic patients treated with typical, not atypical, neuroleptics.

RATIONALE: Clinical studies in patients with schizophrenia suggest that atypical neuroleptics are more effective than typical neuroleptics in reducing negative symptoms including apathy and anhedonia. Dysfunction of the dopaminergic reward system may contribute to negative symptoms in schizophrenia. OBJECTIVE: We used functional magnetic resonance imaging to assess the blood oxygen level dependency response in the ventral striatum of medicated schizophrenics and healthy control subjects during reward anticipation. METHODS: Twenty schizophrenics [ten medicated with typical (e.g., haloperidol) and ten with atypical (e.g., olanzapine and risperidone) neuroleptics] and ten age-matched healthy volunteers participated in an incentive monetary delay task in which visual cues predicted that a rapid response to a subsequent target stimulus would result either in monetary gain or no consequence. RESULTS: Healthy volunteers and schizophrenics treated with atypical neuroleptics showed ventral striatal activation in response to reward-indicating cues, but schizophrenics treated with typical neuroleptics did not. In patients treated with typical neuroleptics, decrease in activation of the left ventral striatum was correlated with the severity of negative symptoms. CONCLUSIONS: Failure to activate the ventral striatum during reward anticipation was previously associated with the severity of negative symptoms in schizophrenia and was also found in schizophrenics treated with typical neuroleptics in this study. Significant blunting of ventral striatal activation was not observed in patients treated with atypical neuroleptics, which may reflect the improved efficacy of these drugs in treating negative symptoms.

Adult↗

PubMed2006

Neural correlates of the interaction between transient and sustained processes: a mixed blocked/event-related fMRI study.

Complete understanding of the neural correlates of cognitive processes requires investigation of both event- and state-related correlates of cognitive performance as well as their interaction. Neuroimaging studies using blocked designs confound these two types of processes and studies using event-related designs focus exclusively on the detection of transient effects. Recent fMRI studies used mixed blocked/event-related designs and found that transient and sustained activity can be dissociated, but it is not yet known how event-related and state-related processing interact. Here we used a phonological categorization paradigm in a mixed blocked/event-related design to investigate where in the brain transient activity interacts with sustained activity. Task difficulty was parametrically manipulated based on individually determined categorization thresholds. We found an interaction effect of transient and sustained activity in the left precuneus. In this cortical structure transient activity increased with increasing task difficulty, while sustained neural activity decreased with increasing task difficulty. Our data suggest that sustained activity is enhanced during processing of an easy task, presumably because of ongoing internally cued endogenous processing, still allowing effortless processing of transient stimuli. During performance of a difficult task, sustained activity in the precuneus is reduced to provide resources for processing incoming stimuli. Processing of stimuli that are expected to be difficult elicits increased transient responses independent of the actual physical properties of the stimuli. In showing an interaction between transient and sustained activity in the precuneus, the present results accommodate seemingly diverging results from previous studies using event-related or blocked designs and expand the knowledge emerging from previous studies using mixed blocked/event-related designs.

Acoustic Stimulation↗

PubMed2006

Sex differences in left/right confusion.

In agreement with the literature, females (n=269) gave themselves significantly poorer ratings than males (n=164) in evaluating their ability to make fast and accurate left/right judgments. In order to evaluate the ecological validity of the self-ratings, subjects were tested on a task that required fast and accurate left/right judgments, on a mental rotation task, and on a task that required navigation of a virtual maze. The correlations between the performances and self-ratings were computed. Both males and females who gave themselves very poor LRC (left/right confusion) ratings had significantly lower accuracy scores on the left/right judgement task than males and females with average ratings, but there was no sex-specific relation between LRC ratings and left/right judgements that would explain why females give themselves lower LRC ratings. For females only, a weak correlation between LRC scores and the learning of the virtual maze was observed, but no significant correlations were observed between LRC scores and mental rotation performance. We conclude that self-ratings on left/right confusion questions, although they yield reliable sex differences, are poor predictors of actual performance on spatial tasks that involve left/right judgements. Thus, and in support of earlier speculations (Sholl and Egeth, 1981; Teng and Lee, 1982; Williams et al., 1993), the principal cause of the marked sex differences in LRC self-ratings likely lies in a greater willingness of females to rate themselves more poorly on questions of this type than is the case for men.

Analysis of Variance↗

PubMed2005

Dysfunction of ventral striatal reward prediction in schizophrenia.

BACKGROUND: Negative symptoms may be associated with dysfunction of the brain reward system in schizophrenia. We used functional magnetic resonance imaging (fMRI) to assess the BOLD response in the ventral striatum of unmedicated schizophrenics during presentation of reward-indicating and loss-indicating stimuli. METHODS: A total of 10 schizophrenic men (7 never medicated, 3 unmedicated for at least 2 years) and 10 age-matched healthy male volunteers participated in an incentive monetary delay task, in which visual cues predicted that a rapid response to a subsequent target stimulus would result either in monetary gain or loss or would have no consequence. RESULTS: Compared to healthy controls, unmedicated schizophrenics showed reduced ventral striatal activation during the presentation of reward-indicating cues. Decreased activation of the left ventral striatum was inversely correlated with the severity of negative (and trendwise positive) symptoms. DISCUSSION: Reduced activation in one of the central areas of the brain reward system, the ventral striatum, was correlated with the severity of negative symptoms in medication-free schizophrenics. In unmedicated schizophrenic patients, a high striatal dopamine turnover may increase the "noise" in the reward system, thus interfering with the neuronal processing of reward-predicting cues by phasic dopamine release. This, in turn, may contribute to negative symptoms as such as anhedonia, apathy, and loss of drive and motivation.

Adult↗

PubMed2004

Long-term training affects cerebellar processing in skilled keyboard players.

We studied cerebellar hemodynamic responses in highly skilled keyboard players and control subjects during complex tasks requiring unimanual and bimanual finger movements. Both groups showed strong hemodynamic responses in the cerebellum during the task conditions. However, non-musicians showed generally stronger hemodynamic responses in the cerebellum than keyboard players. We conclude that, due to long-term motor practice a different cortical activation pattern can be visualized in keyboard players. For the same movements fewer neurons need to be recruited. The different volume of the activated cortical areas might therefore reflect the different effort necessary for motor performance in both groups.

Adult↗

PubMed2004

Bimanual versus unimanual coordination: what makes the difference?

Using fMRI, we investigated the neuronal structures controlling bimanual coordination applying a visuomotor coordination task. Recent studies suggest the existence of a widespread network for the neuronal control of bimanual coordination including primary sensorimotor cortices (M1/S1), lateral and medial premotor cortices (PMC, SMA), cingulate motor area (CMA), and cerebellum (CB). In the present study, subjects performed bimanual and unimanual tasks requiring the coordination of two fingers at a time to navigate a cursor on a computer screen. Thus, in contrast to previous studies, we are using appropriate unimanual control (UNI) tasks. By using this new motor task, we identified a similar activation network for uni- and bimanual movements. Subjects exhibited bilateral activations in PMC, SMA, posterior-parietal cortex (PPC), occipital, and inferiotemporal cortex, as well as in the contralateral M1/S1 and ipsilateral CB. We did not find any additional activation when comparing bimanual with unimanual conditions. The lack of significant activation in the comparison "bimanual > unimanual" gives reason to suggest that this network is not limited to the control of bimanual motor actions, but responsible for unimanually coordinated movements as well. Interestingly, we found stronger activations for unimanual as compared to bimanual coordination. We hypothesize that task difficulty (degrees of freedom to control, e.g., number of limbs) is more important in determining which network components are activated and to what extent, compared to the factor of bimanuality. It even seemed to be less demanding for the motor system to control the cursor bimanually compared to the unimanual performance with two adjacent fingers.

Adult↗

PubMed2004

Plasticity of cortical activation related to working memory during training.

OBJECTIVE: Although it is well established that cerebral activation increases with higher task load, the potential effects of training have been investigated over brief periods only. Training is of potential clinical relevance since training programs are an essential part of psychiatric therapy. METHOD: Cerebral activation during a visual spatial working memory task was examined before, during, and after 4 weeks of daily training in nine healthy subjects using functional magnetic resonance imaging. RESULTS: All subjects showed a pronounced activation mainly involving the right inferior frontal gyrus and the right intraparietal sulcus. While the respective regions showed activation increases with improved performance after 2 weeks of training, the activation values decreased at the time of consolidation of performance gains after 4 weeks. CONCLUSIONS: Our results suggest that training-related cerebral activation changes follow an inverse U-shaped quadratic function and raise the prospect of investigating cerebral mechanisms underlying training effects.

Adult↗

PubMed2002

Women and men exhibit different cortical activation patterns during mental rotation tasks.

The strongest sex differences on any cognitive task, favoring men, are found for tasks that require the mental rotation of three-dimensional objects. A number of studies have explored functional brain activation during mental rotation tasks, and sex differences have been noted in some. However, in these studies there was a substantial confounding factor because male and female subjects differed in overall performance levels. In contrast, our functional brain activation study examined cortical activation patterns for males and females who did not differ in overall level of performance on three mental rotation tasks. This allowed us to eliminate any confounding influences of overall performance levels. Women exhibited significant bilateral activations in the intraparietal sulcus (IPS) and the superior and inferior parietal lobule, as well as in the inferior temporal gyrus (ITG) and the premotor areas. Men showed significant activation in the right parieto-occitpital sulcus (POS), the left intraparietal sulcus and the left superior parietal lobule (SPL). Both men and women showed activation of the premotor areas but men also showed an additional significant activation of the left motor cortex. No significant activation was found in the inferior temporal gyrus. Our results suggest that there are genuine between-sex differences in cerebral activation patterns during mental rotation activities even when performances are similar. Such differences suggest that the sexes use different strategies in solving mental rotation tasks.

Adult↗