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Fakultät für Psychologie
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News & Views
Understanding the relation between laterality and mental disorders
Atypical lateralization is observed significantly more often in schizophrenia patients than in the general population, which led several authors to conclude that there is a genetic link between laterality and schizophrenia. However, the molecular genetic evidence for a link between laterality and schizophrenia is weak. In the present article, a multinational team of researchers from the Biopsychology lab and the Bergen fMRI Group in Norway reviewed recent genetic evidence indicates that schizophrenia is not a single disorder but a group of heritable disorders caused by different genotypic networks leading to distinct clinical symptoms. Based on these findings, the researchers suggested a new theoretical framework in which genetic favtors are not mapped on schizophrenia as a whole but on discrete schizophrenia symptoms.
Ocklenburg, S., Güntürkün, O., Hugdahl, K. & Hirnstein, M.,Laterality ad mental disorders in the postgenomic age - A closer lool at schizophrenia and language lateralization, 2015, Neuroscience and Biobehavioral Reviews, 59, 100-110.
News & Views
Dealing with demands: Differences in task-related neuronal activity indicate different action oriented personality styles
People differ in the capacity to regulate emotions, thoughts and behaviors which are directed towards fulfilling one’s intentions. We differentiate between two personality types, termed action-orientation and state-orientation. Action oriented individuals are very efficient in pursuing their intentions. They focus on the relevant information and have no difficulties in taking the necessary steps towards their goal. Yet, state oriented individuals exhibit difficulties in these so called action control strategies. They tend to perseverate on irrelevant information, hindering them to pursue their intentions. This is why these two types are colloquially referred to as “doers” and “brooders”. While it is known that these behavioral differences exist, it is not clear as to whether they also reflect a neuronal deficit in state oriented individuals. Our results revealed that action oriented individuals inhibit more easily irrelevant information than state oriented individuals and also exhibit a different neuronal activity. Compared to state oriented individuals, action oriented individuals displayed a shorter latency of the frontocentral N2, an ERP component that reflects inhibition and cognitive control. These results show for the first time that neuronal processes are accountable for the incapacity of state oriented individuals in pursuing their goals more efficiently. Furthermore, they indicate that therapeutic interventions in different fields (e.g. overweight, addiction) would profit from a more individual perspective. While some strategies might be very successful for action oriented individuals, they might not be so for state oriented individuals.
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How is the semantic information of objects represented through EEG signals?
Oscillations of electroencephalographic (EEG) signals represent the neural activity which reflecting a mental state or cognitive process that arise from the behavioral task and sensory representations across the mental state activity. Previous studies have shown the relation between event-related EEG and sensory-cognitive representation, and have revealed that categorization of presented objects can be successfully recognized using recorded EEG signals when subjects view objects. In this study, we utilized the recording of EEG signals in conjunction with a multivariate pattern recognition technique with the aim of identifying neural activity associated with conceptual representation based on the presentation of semantic categories of objects. Using multivariate stimulus decoding methods, surprisingly, they demonstrated that object discrimination activity is apparent from the phase pattern of EEG signals across the time in low frequency bands (1-4 Hz), but not by the power of oscillatory brain signals in the same frequency band. In contrast, discrimination accuracy from the power of EEG signals has significantly higher than the performance by the phase of EEG signal in the high frequency band (20-30 Hz). Moreover, our results indicate that how the accuracy of prediction changes between various areas of the brain continuously across the time. In particular, we found that, during the object categorization task, the inter-trial phase coherence (IPC) in low frequency bands is significantly higher than other frequencies in various regions of interests. This measure is associated with decoding pattern across the time. These results suggest that the mechanism underlying conceptual representation can be mediated by the phase of oscillatory neural activity.
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Asymmetrical hippocampal networks
Functional hemispheric asymmetry is a common feature of brain organization, yet little is known about how hemispheric dominance is implemented at the neural level. Birds have a strong left-hemisphere asymmetry in navigation. Since the hippocampus plays a key role in spatial orientation, a team of biopsychologists from Bochum as well as Belgian and US American neuroscientists set out to test, if left and right hippocampi have asymmetrically organized hippocampal networks in birds. For this to reveal, they relied on resting state fMRI analyses in awake and sedated birds in scanners with extremely high magnetic field strengths. Indeed, the could show that following seeding in either an anterior or posterior region of the hippocampal formation of homing pigeons and starlings, the emergent functional connectivity maps are consistently larger following seeding of the left hippocampus. Left seedings were also more likely to result in networks that extend to the contralateral hippocampus and outside the boundaries of the hippocampus. The data support the hypothesis that broader functional connectivity is one neural-organizational property that confers, with respect to navigation, a functional dominance to the avian left hippocampus.
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What happens to the communication between the two hemispheres when the corpus callosum is missing?
Previous research indicates that callosal supression is important for the establishment of functional brain asymmetries. In this study researchers from the Biopsychology lab wondered what whould happen to callosal supression when there is no corpus callosum? They tested this in a multimethod neuroimaging approach combining functional and structural connectivity analysis in patients who were born without a corpus callosum and healthy individuals. The study revealed two important features of the corpus callosum. First, in healthy individuals, interhemispheric motor inhibition measured with fMRI is related to properties of specific motor fibers in the corpus callosum. Second, the inhibitory interaction between motor areas is diminished in patients without a corpus callosum. Interestingy, for these patients motor areas in each hemisphere showed symmetric involment in motor functions, indicating a reduced functional brain asymmetry. These results provide novel insights into callosal functions and the establishment and maintenance of functional brain asymmetries in general.