Neuroscience
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Brain aging is marked by a decline in cognitive abilities and associated with neurodegenerative disorders. Recent studies have shown, neurogenesis continues into adulthood but is known to be decreasing during advancing age and these changes may contribute to cognitive alterations. Advances, which aim to promote better aging are of paramount importance. ⋯ In contrast, DR shortened telomere lengths only in young animals. Neither age nor DR changed the differentiation patterns of glial cells. Our results suggest that the potential effects of DR could be mediated by telomere regulation and whether these are beneficial or negative remains to be determined.
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Using an immunohistochemical technique, we mapped the immunoreactive structures containing methionine-enkephalin-Arg(6)-Gly(7)-Leu(8) (Met-8) (a marker for the pro-enkephalin system) in the human diencephalon. Compared with previous studies, we observed a more widespread distribution of Met-8 in the human diencephalon. Met-8-immunoreactive cell bodies and fibers exhibited a more widespread distribution in the hypothalamus than in the thalamus. ⋯ A moderate density was observed in the paraventricular thalamic nucleus, reuniens thalamic nucleus, lateral and medial geniculate nuclei, dorsomedial hypothalamic nucleus, paraventricular hypothalamic nucleus (posterior part) and ventromedial hypothalamic nucleus. The present study is the first to demonstrate the presence of clusters of Met-8-immunoreactive cell bodies in the human thalamus and hypothalamus, the distribution of fibers containing neuropeptides in the hypothalamus and the presence of these fibers in several thalamic nuclei. This neuroanatomical study will serve to elucidate the physiological roles of Met-8 in future studies of the human diencephalon.
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Review
Parieto-frontal gradients and domains underlying eye and hand operations in the action space.
In monkeys, motor intention in its different forms emerges from a parietal-frontal gradient of visual, eye and hand signals, containing discrete dominant domains. These are formed by areas sharing cortical connections and functional properties. Within this gradient, the combination of different inputs determines the tuning properties of neurons, while local and long cortico-cortical connections shape the structure and temporal delays of the network. ⋯ This eye-hand matrix provides a framework to address, within a unitary frame, not only basic forms of motor behavior, such as reaching and grasping, but also actions of increasing complexity, such as interception of moving targets, tool use, construction of complex objects, maze analysis and solution, among others. The organization of the cerebral cortex into functional gradients and domains, beyond frontal and parietal cortices, is common to other brain regions, such as prefrontal cortex and hippocampus, and does not support views of the parieto-frontal operations based on specific and strictly segregated eye and hand modules. These can only be found at the eye and hand motor output domains in the frontal cortex, that is in the frontal eye fields and in the primary motor cortex, respectively.
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Mitochondrial changes and oxidative stress in a mouse model of Zellweger syndrome neuropathogenesis.
Zellweger syndrome (ZS) is a peroxisome biogenesis disorder that involves significant neuropathology, the molecular basis of which is still poorly understood. Using a mouse model of ZS with brain-restricted deficiency of the peroxisome biogenesis protein PEX13, we demonstrated an expanded and morphologically modified brain mitochondrial population. ⋯ Similar overall changes were observed for glial cells. In toto, these findings suggest that mitochondrial oxidative stress and aberrant mitochondrial dynamics are associated with the neuropathology arising from PEX13 deficiency.
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Trigeminal neuropathic pain is described as constant excruciating facial pain. The study goal was to investigate the role of nucleus locus coeruleus (LC) in a model of chronic orofacial neuropathic pain (CCI-ION). The study examines LC's relationship to both the medullary dorsal horn receiving trigeminal nerve sensory innervation and the medial prefrontal cortex (mPFC). ⋯ Microinjection of NAα1 receptor antagonist, benoxathian, into mPFC attenuated whisker pad hypersensitivity, while NAα2 receptor antagonist, idazoxan, was ineffective. Thus, GABAA-mediated activation of NA neurons during CCI-ION can facilitate hypersensitivity through NAα1 receptors in the mPFC. These data indicate LC is a chronic pain generator.