Neuroscience
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Gamma time-frequency responses (TFRs) induced by painful laser in the contralateral primary somatosensory (SI) cortex have been shown to correlate with perceived pain-intensity in human. Given the functional roles of gamma TFRs in the cortical spaces, it remains unclear whether such a relationship is sustained for other brain regions where the laser-evoked potentials (LEPs) are presented. In this study, we delivered the painful laser pluses at random pain-intensity levels (i.e. strong, medium and weak) in a single train to the dorsal hand of six patients with uncontrolled epilepsy. ⋯ Our results showed that gamma TFRs are not modality specific, but the largest gamma TFRs were consistently found within the SI region and noxious laser elicited significantly stronger gamma TFRs than innocuous nonpainful vibratory stimuli. Furthermore, stronger pain induced stronger gamma TFRs in the cortices of SI (r=0.4, p<0.001) and PS (r=0.29, p=0.005). Given that potentially harmful noxious stimulus would automatically capture greater attention than the innocuous ones, our results support the hypothesis that the degree of SI and PS gamma TFRs is associated with an attentional drive provoked by painful stimuli.
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The purpose of the present study was to characterize the properties of A-type GABA receptor (GABAA receptor) currents in human sensory neurons. Neurons were obtained from adult organ donors. GABAA currents were recorded in isolated neurons. ⋯ The GABA current equilibrium potential was ∼ 20 mV more hyperpolarized than in rat neurons. Both low- and high-affinity currents were increased by inflammatory mediators but via different second messenger pathways. These results highlight potentially important species differences in the properties of ion channels present in their native environment and suggest the use of human sensory neurons may be a valuable tool to test compounds prior to use in humans.
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Ambulatory instability and falls are a major source of morbidity in the elderly. Age-related loss of tendon reflexes is a major contributing factor to this morbidity, and deterioration of the afferent limb of the stretch reflex is a potential contributing factor to such age-dependent loss of tendon reflexes. To evaluate this, we assessed the number and distribution of muscle spindle afferent fibers in human sacral spinal ganglia (S1) and tibial nerve samples obtained at autopsy, using immunohistochemical staining for the α3 isoform of Na(+), K(+)-ATPase (α3NKA), a marker of muscle spindle afferents. ⋯ However, as compared to younger subjects, the population of α3NKA-positive neurons from advanced-age subjects showed diminished numbers of large (both moderately and strongly labeled), and medium-sized (strongly labeled) profiles. Considering the critical significance of ion transport by NKA for neuronal activity, our data suggest that functional impairment and, also, most likely atrophy and/or degeneration of muscle spindle afferents, are mechanisms underlying loss of tendon reflexes with age. The larger and more strongly α3NKA-expressing spindle afferents appear to be proportionally more vulnerable.
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Estrogen Receptor Variant ER-α36 is involved in Estrogen Neuroprotection Against Oxidative Toxicity.
It is well known that estrogen exerts neuroprotective effect against various neuronal damages. However, the estrogen receptor (ER) that mediates estrogen neuroprotection has not been well established. In this study, we investigated the potential receptor that mediates estrogen neuroprotection and the underlying molecular mechanisms. ⋯ We also studied the rapid estrogen signaling mediated by ER-α36 in neuroprotective effect and found the PI3K/AKT and MAPK/ERK1/2 signaling mediated by ER-α36 is involved in estrogen neuroprotection. We also found that GPER, an orphan G protein-coupled receptor, is not involved in ER-α36-mediated rapid estrogen response. Our study thus demonstrates that ER-α36-mediated rapid estrogen signaling is involved in the neuroprotection activity of estrogen against oxidative toxicity.
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Aim of this study was to verify whether the topological organization of human brain functional networks is different for males and females in resting state EEGs. Undirected and weighted brain networks were computed by eLORETA lagged linear connectivity in 130 subjects (59 males and 71 females) within each hemisphere and in four resting state networks (Attentional Network (AN), Frontal Network (FN), Sensorimotor Network (SN), Default Mode Network (DMN)). ⋯ Gender small-worldness differences in some of resting state networks indicated that there are specific brain differences in the EEG rhythms when the brain is in the resting-state condition. These specific regions could be considered related to the functions of behavior and cognition and should be taken into account both for research on healthy and brain diseased subjects.