Neuroscience
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Selecting and moving to spatial targets are critical components of goal-directed behavior, yet their neural bases are not well understood. The superior colliculus (SC) is thought to contain a topographic map of contralateral space in which the activity of specific neuronal populations corresponds to particular spatial locations. However, these spatial representations are modulated by several decision-related variables, suggesting that they reflect information beyond simply the location of an upcoming movement. ⋯ However, in noncompetitive trials, some neurons lost their spatial selectivity and in others activity predicted movement to ipsilateral targets. Consistent with these findings, unilateral optogenetic inactivation of pre-movement SC activity ipsiversively biased competitive, but not noncompetitive, trials. Incorporating these results into an attractor model of SC activity points to distinct pathways for orienting movements under competitive and noncompetitive conditions, with the SC specifically required for selecting among multiple potential targets.
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Amyloid beta peptide (Aβ) is implicated in the development of pathological reactions associated with Alzheimer's disease (AD), such as oxidative stress, neuro-inflammation and death of brain cells. Current pharmacological approaches to treat AD are not able to control the deposition of Aβ and suppression of Aβ-induced cellular response. There is a growing body of evidence that exposure to radiofrequency electromagnetic field (RF-EMF) causes a decrease of beta-amyloid deposition in the brains and provides cognitive benefits to Alzheimer's Tg mice. ⋯ Our data demonstrate that EMF is able to reduce Aβ42- and H2O2-induced cellular ROS, abrogate Aβ₄₂-induced production of mitochondrial ROS and the co-localization between the cytosolic (p47-phox) and membrane (gp91-phox) subunits of NADPH oxidase, while increasing MMP, and inhibiting H2O2-induced phosphorylation of p38MAPK and ERK1/2 in primary astrocytes. Yet, EMF was not able to modulate alterations in the phosphorylation state of the MAPKs triggered by Aβ42. Our findings provide an insight into the mechanisms of cellular and molecular responses of astrocytes on RF-EMF exposure and indicate the therapeutic potential of RF-EMF for the treatment of Alzheimer's disease.
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The subplate (SP) represents a transitory cytoarchitectural fetal compartment containing most subcortical and cortico-cortical afferents, and has a fundamental role in the structural development of the healthy adult brain. There is evidence that schizophrenia and autism may be determined by developmental defects in the cortex or cortical circuitry during the earliest stages of pregnancy. ⋯ The SP has been described as a cortical amplifier with a role in the coordination of cortical activity, and sensitive growth and migration windows have crucial consequences with respect to cognitive functioning. Although there are not enough studies to draw final conclusions, improved knowledge of the SP's role in schizophrenia and autism spectrum disorders may help to elucidate and possibly prevent the onset of these two severe disorders.
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Noradrenaline (NA) modulates the spinal motor networks for locomotion and facilitates neuroplasticity, possibly assisting neuronal network activation and neuroplasticity in the recovery phase of spinal cord injuries. However, neither the effects nor the mechanisms of NA on synaptic transmission and neuronal excitability in spinal ventral horn (VH) neurons are well characterized, especially in rats aged 7 postnatal days or older. To gain insight into NA regulation of VH neuronal activity, we used a whole-cell patch-clamp approach in late neonatal rats (postnatal day 7-15). ⋯ At a holding potential of 0 mV, NA also increased frequency and amplitude of both GABAergic and glycinergic inhibitory postsynaptic currents via the activation of somatic adrenoceptors in presynaptic neurons. In current-clamp recordings, NA depolarized resting membrane potentials and increased the firing frequency of action potentials in VH neurons, indicating that it enhances the excitability of these neurons. Our findings provide new insights that establish NA-based pharmacological therapy as an effective method to activate neuronal networks of the spinal VH in the recovery phase of spinal cord injuries.