Neuroscience
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How gravity influences neural control of arm movements remains under debate. We tested three alternative interpretations suggested by previous research: (1) that muscular control includes two components, tonic which compensates for gravity and phasic which produces the movement; (2) that there is a tendency to exploit gravity to reduce muscle effort; and (3) that there is a tendency to use a trailing pattern of joint control during which either the shoulder or elbow is rotated actively and the other joint rotates predominantly passively, and to exploit gravity for control of the passively rotated joint. A free-stroke drawing task was performed that required production of center-out strokes within a circle while selecting stroke directions randomly. ⋯ To test the three interpretations, we used a kinetic analysis that determined the role of gravitational torque in the production of movement in the preferred directions. The results supported the third interpretation and provided evidence against the first and second interpretation. The trailing pattern has been associated with reduced neural effort for joint coordination, and therefore, we conclude that the major tendency with respect to gravity is to exploit it for simplification of joint coordination.
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Our previous studies have suggested a strong involvement of serotonergic innervations in epileptogenesis and associated memory impairment. Several studies have suggested that the modulation of 5-HT3 receptors could serve as a promising tool for the management of epilepsy and memory deficit. The present study was envisaged to confirm this hypothesis. ⋯ Ondansetron treatment significantly reduced the seizure severity and improved the acquisition performance in a dose-dependent manner. Neurochemical analysis suggested that ondansetron treatment significantly reduced the nitrite level and AChE activity in the cortex as well as in the hippocampus. The outcome of this study suggests the reduction in AChE activity and the nitrite level could be considered as protective mechanisms of ondansetron for amelioration of PTZ kindling and associated memory deficit.
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The medial prefrontal cortex (mPFC) plays a key role in higher functions such as memory and attention. In order to demonstrate sensory responses in the mPFC, we used electrophysiological recordings of urethane-anesthetized rats to record somatosensory-evoked potentials (SEPs) or auditory-evoked potentials (AEPs) elicited by whisker deflections and click stimulation, respectively. Contralateral whisker stimulation or auditory stimuli were also applied to study sensory interference in the mPFC. ⋯ Results obtained from retrograde tracer injections in the dorsal and ventral regions of the mPFC indicated that somatosensory and auditory sensory inputs may arrive at the dorsal mPFC through secondary sensory cortical areas, and through the insular and temporal cortical areas. The ventral mPFC may receive sensory information through the strong anatomical connections between the dorsal and ventral mPFC areas. In conclusion, results suggest mPFC plays an important role in sensory processing, which may have important implications in attentional and memory processes.
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To save energy, the European directives from the Eco-design of Energy Using Products (2005/32/CE) have recommended the replacement of incandescent lamps by more economic devices such as Light Emitting Diodes (LEDs). However, the emission spectrum of these devices is enriched in blue radiations, known to be potentially dangerous to the retina. Recent studies showed that light exposure contributes to the onset of early stages of age-related macular degeneration (AMD). ⋯ Twenty-four hours exposure at high luminance was compared to a cyclic (dark/light) exposure at domestic levels for 1week and 1month, using different LEDs (Cold-white, blue and green), as well as fluorocompact bulbs and fluorescent tubes. The data suggest that the blue component of the white-LED may cause retinal toxicity at occupational domestic illuminance and not only in extreme experimental conditions, as previously reported. It is important to note that the current regulations and standards have been established on the basis of acute light exposure and do not take into account the effects of repeated exposure.
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Reactive astrocytosis and the subsequent glial scar is ubiquitous to injuries of the central nervous system, especially spinal cord injury (SCI) and primarily serves to protect against further damage, but is also a prominent inhibitor of regeneration. Manipulating the glial scar by targeting chondroitin sulfate proteoglycans (CSPGs) has been the focus of much study as a means to improve axon regeneration and subsequently functional recovery. ⋯ Furthermore, conditioned medium taken from treated Neu7s, or co-culture experiments with dorsal root ganglia (DRG) showed that siRNA treatment resulted in a more permissive environment for DRG neurite outgrowth than treatment with chondroitinase ABC alone. These results indicate that there is a role for targeted siRNA therapy using polymeric vectors to facilitate regeneration of injured axons following central nervous system injury.