Neuroscience
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Males are more susceptible than females to long-term cognitive deficits following neonatal hypoxic-ischemic encephalopathy (HIE). Mitochondrial dysfunction is implicated in the pathophysiology of cerebral hypoxia-ischemia (HI), but the influence of sex on mitochondrial quality control (MQC) after HI is unknown. Therefore, we tested the hypothesis that mitophagy is sexually dimorphic and neuroprotective 20-24h following the Rice-Vannucci model of rat neonatal HI at postnatal day 7 (PN7). ⋯ Moreover, neuronal cell death with NeuN/TUNEL co-staining occurred in both hemispheres of male brain, but only in the ipsilateral hemisphere of female brain after HI. In summary, mitophagy induction and neuronal cell death are sex dependent following HI. The deficit in elimination of damaged/dysfunctional mitochondria in the male brain following HI may contribute to male vulnerability to neuronal death and long-term neurobehavioral deficits following HIE.
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Intravenous infusion of mesenchymal stem cells (MSCs) derived from adult bone marrow improves behavioral function in rat models of spinal cord injury (SCI). However, most studies have focused on the acute or subacute phase of SCI. In the present study, MSCs derived from bone marrow of rats were intravenously infused 10weeks after the induction of a severe contusive SCI. ⋯ Immunohistochemical staining for RECA-1 and PDGFR-β showed increased microvasculature/repair-neovascularization in MSC-treated rats. There was extensive remyelination around the lesion center and increased sprouting of the corticospinal tract and serotonergic fibers after MSC infusion. These results indicate that the systemic infusion of MSCs results in functional improvement that is associated with structural changes in the chronically injured spinal cord including stabilization of the BSCB, axonal sprouting/regeneration and remyelination.
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Investigation of the neural basis of self-generated thought is moving beyond a simple identification with default network activation toward a more comprehensive view recognizing the role of the frontoparietal control network and other areas. A major task ahead is to unravel the functional roles and temporal dynamics of the widely distributed brain regions recruited during self-generated thought. We argue that various other neuroscientific methods - including lesion studies, human intracranial electrophysiology, and manipulation of neurochemistry - have much to contribute to this project. ⋯ Human intracranial electrophysiology illuminates how and where in the brain thought is generated and where this activity subsequently spreads. Finally, measurement and manipulation of neurotransmitter and hormone levels can clarify what kind of neurochemical milieu drives or facilitates self-generated cognition. Integrating evidence from multiple complementary modalities will be a critical step on the way to improving our understanding of the neurobiology of functional and dysfunctional forms of self-generated thought.
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Patients with Parkinson's disease (PD) often present with bimanual coordination deficits whose exact origins remain unclear. One aspect of bimanual coordination is inter-limb coupling. This is characterized by the harmonization of movement parameters between limbs. ⋯ However, PD patients did not exhibit spatial inter-limb coupling. Again, this was not altered by medication or stimulation. Collectively, the results suggest that structures independent of the dopaminergic system and basal ganglia may mediate temporal and spatial inter-limb coupling.
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Repetitive transcranial magnetic stimulation (rTMS) has become a popular method of modulating neural plasticity in humans. Clinically, rTMS is delivered at high intensities to modulate neuronal excitability. While the high-intensity magnetic field can be targeted to stimulate specific cortical regions, areas adjacent to the targeted area receive stimulation at a lower intensity and may contribute to the overall plasticity induced by rTMS. ⋯ Increases in spike firing frequency were present throughout the 20min post-stimulation whereas action potential (AP) threshold hyperpolarization was present immediately after stimulation and at 20min post-stimulation. These results provide evidence that LI-rMS alters neuronal excitability of excitatory neurons. We suggest that regions outside the targeted region of high-intensity rTMS are susceptible to neuromodulation and may contribute to rTMS-induced plasticity.