Arch Ital Biol
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Comparative Study
Influence of mental motor imagery on the execution of a finger-to-thumb opposition task.
The present fMRI study compares regional distribution of the cortical activity during the execution of unilateral hand movements (finger-to-thumb opposition) preceded or not by their motor simulation (S + E and E condition, respectively). The results show that, overall, the number and the spatial distribution of activated voxels are both increased in the S + E with respect to the E condition. ⋯ The activity increase may be accounted by a sort of neural recruiting that is made possible by the overlapping of cortical networks involved in both motor output and motor imagery. The beneficial effects of "mental practice" on the physical performance may rely to the close temporal association between motor rehearsal and actual performance.
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Biography Historical Article
Rita Levi-Montalcini and the discovery of nerve growth factor: past and present studies.
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Following peripheral nerve injury perineuronal satellite cell reaction in the corresponding spinal ganglion is observed. The mechanisms underlying the glial responses to axon injury remain unknown. In an immunocytochemical and morphometric study we investigated satellite cell and macrophage responses in the rat L4 and L5 dorsal root ganglia (DRG) during the seven days immediately after unilateral sciatic nerve crush or transection. ⋯ We found no significant differences between the increases provoked by the two types of nerve lesion, but the macrophage activation was detected earlier after nerve transection than after crush. No correlation was detected between satellite cells and macrophages reactions over the 7 day period we examined. These findings support the idea that intercellular neuron-glial diffusible signals play a major role in DRG glial cell response to peripheral nerve lesion.
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Recent work indicates that the orexin/hypocretin-containing neurons of the lateral hypothalamus are involved in control of REM sleep phenomena, but site-specific actions in control of wakefulness have been less studied. Orexin-containing neurons project to both brainstem and forebrain regions that are known to regulate sleep and wakefulness, including the field of cholinergic neurons in the basal forebrain (BF) that is implicated in regulation of wakefulness, and includes, in the rat, the horizontal limb of the diagonal band, the substantia innominata, and the magnocellular preoptic region. The present study used microdialysis perfusion of orexin-A directly in the cholinergic BF region of rat to test the hypothesis that orexin-A enhances W via a local action in the BF. ⋯ Orexin-A perfusion also produced a significant dose-dependent decrease in nonREM sleep, and a trend-level decrease in REM sleep. The results clearly demonstrate a potent capacity of orexin-A to induce wakefulness via a local action in the BF, and are consistent with previous work indicating that the BF cholinergic zone neurons have a critical role in the regulation of EEG activation and W. The data suggest further that orexin-A has a significant role in the regulation of arousal/wakefulness, in addition to the previously described role of orexin in the regulation and expression of REM sleep and REM sleep-related phenomena.