Brain research
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The left parietal cortex contributes to goal-directed hand movement. In this study, we targeted this region with transcranial magnetic stimulation (TMS) to assess the effects on a wider distributed circuitry related to motor control. Ten healthy subjects underwent 3 Tesla functional magnetic resonance imaging (fMRI) with interleaved TMS. ⋯ Movement imagery after TMS showed significantly increased activation in the left medial prefrontal cortex, right lateral prefrontal cortex, left supramarginal gyrus and right occipital cortex, while a decrease was present in bilateral anterior parietal cortex (P<0.01 voxel-level; P<0.05 volume corrected). Activation changes after TMS of left superior parietal cortex thus appears to increase prefrontal and posterior parietal cortex activation, associated with a reduced function of the anterior parietal cortex, including S2. These changes are thought to reflect an impaired ability to estimate the proprioceptive consequences of movement during its preparation, which is compensated by the increased contribution of more remote parietal and prefrontal cortical regions.
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Patients who have suffered nerve injury show profound inter-individual variability in neuropathic pain even when the precipitating injury is nearly identical. Variability in pain behavior is also observed across inbred strains of mice where it has been attributed to genetic polymorphisms. Identification of cellular correlates of pain variability across strains can advance the understanding of underlying pain mechanisms. ⋯ Following nerve injury, the residual mRNA levels of Na(v)1.6 (downregulated in two of the strains) correlated tightly to the extent of autotomy behavior. A suggestive correlation was also seen for the post-injury mRNA levels of Contactin (downregulated in all strains) with autotomy. Thus, our results suggest a contribution by DRG Na(v)1.6, and possibly Contactin to neuropathic pain in the neuroma model in mice.
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In social contexts, facial expressions are dynamic in nature and vary rapidly in relation to situational requirements. However, there are very few fMRI studies using dynamic emotional stimuli. The aim of this study was (1) to introduce and evaluate a new stimulus database of static and dynamic emotional facial expressions according to arousal and recognizability investigated by a rating by both participants of the present fMRI study and by an external sample of 30 healthy women, (2) to examine the neural networks involved in emotion perception of static and dynamic facial stimuli separately, and (3) to examine the impact of motion on the emotional processing of dynamic compared to static face stimuli. ⋯ These regions have been discussed to be associated with emotional memory encoding, the perception of threat, facial identity, biological motion, the mirror neuron system, an increase of emotional arousal, and reward processing, respectively. Post hoc ratings of the dynamic stimuli revealed a better recognizability in comparison to the static stimuli. In conclusion, dynamic facial expressions might provide a more appropriate approach to examine the processing of emotional face perception than static stimuli.
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Neurotrophic factors (NTFs), beside regulating neuronal survival in the central and peripheral nervous system, are also involved in the modulation of neuronal function in the adult animal. Both brain-derived neurotrophic factor (BDNF) and glial cell-derived neurotrophic factor (GDNF) levels are altered in pathological pain states, and exogenous BDNF and GDNF have multiple effects on pain behavior, depending on the animal model (i.e. inflammatory vs. neuropathic). Thermally gated TRP channels TRPM8, TRPA1 and TRPV1 play a significant role in pain signaling and their pattern and level of expression as well as their biophysical properties are altered in chronic pain states. ⋯ Moreover, BDNF treatment increased the amplitude of the response to both AITC and capsaicin. Acute treatment with both NTFs leads to a reduction in the magnitude of tachyphylaxis to noxious stimuli (heat and AITC). Overall, our data provides evidence for a role of BDNF and GDNF in regulating the pattern of expression and level of activity of the transducer channels TRPA1 and TRPV1, leading to enhanced neuronal sensitivity to painful stimuli and increased co-expression of thermoTRP channels.
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MicroRNAs (miRNAs) are very important regulators of biological processes such as development, cellular differentiation, and tumor generation. MiRNA microarray has been found to be a high throughput global analysis tool for detecting miRNA expression profiling, and miRNA expression profiling will facilitate the study of the biological function of miRNAs. In this report, we describe the miRNA expression level in rat cerebral cortex after traumatic brain injury using microarray method. ⋯ Finally, we utilized qRT-PCR methods to verify the microarray results. The qRT-PCR results indicated good consistency with the results of the microarray method. Our microarray based analysis of microRNA expression in rat cerebral cortex after traumatic brain injury has shown that some microRNA such as miR-21 could be involved in the intricate process of TBI course.