Neuroscience
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Tinnitus is a bothersome phantom sound percept and its neural correlates are not yet disentangled. Previously published papers, using [(18)F]-fluoro-deoxyglucose positron emission tomography (FDG-PET), have suggested an increased metabolism in the left primary auditory cortex in tinnitus patients. This unilateral hyperactivity has been used as a target in localized treatments such as transcranial magnetic stimulation. ⋯ Nevertheless, the activity in the left primary auditory cortex was higher than in the right primary auditory cortex, but this asymmetry was present in both tinnitus patients and control subjects. In contrast, the lateralization in secondary auditory cortex was opposite, with higher activation in the right hemisphere. These data show that hemisphere asymmetries in the metabolic resting activity of the auditory cortex are present, but these are not associated with tinnitus and are a normal characteristic of the normal brain.
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In this study we were interested in the neural system supporting the audiovisual (AV) integration of emotional expression and emotional prosody. To this end normal participants were exposed to short videos of a computer-animated face voicing emotionally positive or negative words with the appropriate prosody. Facial expression of the face was either neutral or emotionally appropriate. ⋯ In trials showing emotional expressions compared to neutral trials univariate analysis showed activation primarily in bilateral amygdala, fusiform gyrus, middle temporal gyrus/superior temporal sulcus and inferior occipital gyrus. When employing either the left amygdala or the right amygdala as a seed region in RFX-GCM we found connectivity with the right hemispheric fusiform gyrus, with the indication that the fusiform gyrus sends information to the Amygdala. These results led to a working model for face perception in general and for AV-affective integration in particular which is an elaborated adaptation of existing models.
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Obesity resistance due to elevated orexin signaling is accompanied by high levels of spontaneous physical activity (SPA). The behavioral and neural mechanisms underlying this observation have not been fully worked out. We determined the contribution of hypothalamic orexin receptors (OXRs) to SPA stimulated by orexin A (OXA), whether OXA-stimulated SPA was secondary to arousal and whether voluntary wheel running led to compensations in 24-h SPA. ⋯ Obesity-resistant rats ran more and wheel running was directly related to 24-h SPA levels. The OX1R antagonist, SB-334867-A, and the DA1R antagonist, SCH3390, in SN more effectively reduced SPA stimulated by OXA in obesity-resistant rats. These data suggest OXA-stimulated SPA is not secondary to enhanced arousal, propensity for SPA parallels inclination to run and that orexin action on dopaminergic neurons in SN may participate in the mediation of SPA and running wheel activity.
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Parkinson's disease (PD) is the second most frequent neurodegenerative disorder afflicting 2% of the population older than 65 years worldwide. Recently, brain organotypic slices have been used to model neurodegenerative disorders, including PD. They conserve brain three-dimensional architecture, synaptic connectivity and its microenvironment. ⋯ In addition, a significant decline of medium spiny neuron density was observed from days 7 to 16. These sagittal organotypic slices could be used to study the early stage of PD, namely dopaminergic degeneration, and the late stage of the pathology with dopaminergic and GABAergic neuron loss. This novel model might improve the understanding of PD and may represent a promising tool to refine the evaluation of new therapeutic approaches.
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Recent studies have demonstrated that transcranial direct current stimulation (tDCS) modulates cortical activity in the human brain. In the language domain, it has already been shown that during a naming task tDCS reduces vocal reaction times in healthy individuals and speeds up the recovery process in left brain-damaged aphasic subjects. In this study, we wondered whether tDCS would influence the ability to articulate tongue twisters during a repetition task. ⋯ No significant differences were observed among the three time points during the sham condition. We believe that these data clearly confirm that the left frontal region is critically involved in the process of speech repetition. They are also in line with recent evidence suggesting that frontal tDCS might be used as a therapeutic tool in patients suffering from articulatory deficits.