Neuroscience
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Bone morphogenetic proteins (BMPs) exert its biological functions by interacting with membrane bound receptors. However, functions of BMPs are also regulated in the extracellular space by secreted antagonistic regulators. Chordin is an extracellular BMP antagonist that binds BMP-2, 4, and 7 with high affinity and thus interferes with binding to BMP receptors. ⋯ In addition, abundant chordin expression was also observed in the neuropil of the gray matters where high plasticity is reported, such as the molecular layer of the cerebellum and the superficial layer of the superior colliculus. Furthermore, we found that astrocytes and ependymal cells also express chordin protein. These data indicate that chordin is more widely expressed throughout the adult CNS than previously reported, and its continued abundant expression in the adult brain strongly supports the idea that chordin plays pivotal roles also in the adult brain.
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Neurons in the auditory system are spatially organized in their responses to pure tones, and this tonotopy is expected to predict neuronal responses to more complex sounds such as vocalizations. We presented vocalizations with low-, medium- and high-frequency content to determine if selectivity of neurons in the inferior colliculus (IC) of mice respects the tonotopic spatial structure. Tonotopy in the IC predicts that neurons located in dorsal regions should only respond to low-frequency vocalizations and only neurons located in ventral regions should respond to high-frequency vocalizations. ⋯ We then used a nonlinear model of signal transduction in the cochlea that generates distortion products to predict neural responses to the vocalizations. We found that these predictions more closely matched the actual neural responses. Our findings suggest that the cochlea distorts the frequency representation in vocalizations and some neurons use this distorted representation to encode the vocalizations.
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Numerous epidemiological studies have shown an association between pesticide exposure and the increased risk of developing Parkinson's disease. Previously we have reported that Dichlorvos exposure can induce oxidative stress, resulting in over-expression of pro-apoptotic genes and finally caspase-dependent nigrostriatal dopaminergic neuronal cell death in rat brain. Here, we examined the effect of caspase inhibition on PC12 cell death induced by Dichlorvos (30 μM). ⋯ Subsequent release of the apoptosis-inducing factor (AIF) from mitochondria and its translocation into the nucleus was also prevented by PJ34 pretreatment. In conclusion, the results of the present study show that caspase inhibition without concurrent inhibition of PARP1 is unlikely to be effective in preventing cell death because in the presence of the caspase inhibitor, caspase-independent cell death predominates due to PARP activation. These results suggest that combined therapeutic strategies directed at multiple cell death pathways may provide superior neuroprotection than those directed at a single mechanism.
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Subliminal electromagnetic fields (EMFs) triggered nonlinear evoked potentials in awake but not anesthetized animals, and increased glucose metabolism in the hindbrain. Field detection occurred somewhere in the head and possibly was an unrecognized function of sensory neurons in facial skin, which synapse in the trigeminal nucleus and project to the thalamus via glutamate-dependent pathways. If so, anesthetic agents that antagonize glutamate neurotransmission would be expected to degrade EMF-evoked potentials (EEPs) to a greater extent than agents having different pharmacological effects. ⋯ In contrast, neither EEPs nor AEPs were observed when anesthesia was produced partly or wholly using ketamine. The duration and latency of the EEPs was unaltered by xylazine anesthesia. The afferent signal triggered by the transduction of weak EMFs was likely mediated by NMDAR-mediated glutamate neurotransmission.
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It was the aim of the present study to investigate menstrual cycle effects on selective attention and its underlying functional cerebral networks. Twenty-one healthy, right-handed, normally cycling women were investigated by means of functional magnetic resonance imaging using a go/no-go paradigm during the menstrual, follicular and luteal phase. On the behavioral level there was a significant interaction between visual half field and cycle phase with reaction times to right-sided compared to left-sided stimuli being faster in the menstrual compared to the follicular phase. ⋯ Functional imaging, however, did not reveal clear-cut menstrual phase-related changes in activation pattern in parallel to these behavioral findings. A functional connectivity analysis identified differences between the menstrual and the luteal phase: During the menstrual phase, left inferior parietal cortex showed a stronger negative correlation with the right middle frontal gyrus while the left medial frontal cortex showed a stronger negative correlation with the left middle frontal gyrus. These results can serve as further evidence of a modulatory effect of steroid hormones on networks of lateralized cognitive functions not only by interhemispheric inhibition but also by affecting intrahemispheric functional connectivity.