Neuroscience
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Speech recognition in a multi-talker situation poses high demands on attentional and other central resources. This study examines the relationship between age, cognition and speech recognition in tasks that require selective or divided attention in a multi-talker setting. Two groups of normal-hearing adults (one younger and one older group) were asked to repeat utterances from either one or two concurrent speakers. ⋯ In comparison, speech recognition for tests requiring divided attention could be more strongly determined by neuropsychological probes of fluid intelligence. The findings of this study indicate that - apart from hearing impairment - cognitive aspects account for the typical difficulties of older listeners in a multi-speaker setting. Our results are discussed in the context of evidence showing that frontal lobe functions in terms of working memory and fluid intelligence generally decline with age.
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Our previous studies demonstrated that exposure of animals to acute stress immediately induced morphological microglial activation in the brain. Here we investigated the effects of adrenal corticoids on microglial activation following acute stress. ⋯ Thus, while acute stress has the ability to activate microglia, the magnitude of activation is negatively regulated by CORT. Glucocorticoids may serve as an important endogenous suppressive signal limiting neuroinflammation that might otherwise occur during stress.
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Neuropathy is often seen in uncontrolled diabetes and the mechanisms involved for neuropathic pain are poorly understood. Hyperglycemia is a consequence of chronic uncontrolled diabetes and it is postulated to produce neuropathic pain. Therefore, in this study, we have investigated the effects of hyperglycemia on Na(+) channel kinetics in cultured dorsal root ganglion (DRG) neurons from neonatal rats using whole-cell patch-clamp technique. ⋯ The depression observed with CBZ in the presence of high glucose, i.e., 45 mM (86.5±4.9%) was significantly greater than control (61.6±1.8%). Hyperglycemia also increased reactive oxygen species (ROS) activity and was attenuated by CBZ. These results suggest that short-term exposure of DRG neurons to high glucose concentrations enhance the Na(+) channel activity, and were attenuated by CBZ via ROS-dependent mechanisms.
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Synaptic activity is a spatially limited process that requires a precise, yet dynamic, complement of proteins within the synaptic micro-domain. The maintenance and regulation of these synaptic proteins is regulated, in part, by local mRNA translation in dendrites. ⋯ In this review, we discuss the identity of proteins synthesized within dendrites, the receptor-mediated mechanisms regulating their synthesis, and the possible roles for these locally synthesized proteins. We also explore how our current understanding of dendritic protein synthesis in the hippocampus can be applied to new brain regions and to understanding the pathological mechanisms underlying varied neurological diseases.
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Middle-aged Americans have higher obesity rates than any other age group, yet little is known about age-related changes in central taste function during this critical time. Research on taste and aging has primarily focused on psychophysical responses, and on older adults. Central taste processing in middle-age has not been investigated. ⋯ Further inspection of the age-by-taste interaction revealed that there was a significant effect of age (greater activation in young adults) in sensory (insula) and reward (lentiform nucleus) regions during hedonic evaluation of the sweet taste; however, there was no age effect in the bitter taste condition. Further, young adults had greater responses during hedonic evaluation of sucrose than of caffeine in several sensory and motor processing regions (pre- and postcentral gyri, insula), but there were no taste-related differences in activation in the middle-aged adults. We speculate that these results might reflect early age-related differences in central taste processing that occur prior to deficits in gustatory function observed in old age, and this might have important implications for weight changes that occur during middle-age.