Neuroscience
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The intrinsic properties of spherical neurons play a fundamental role in the sensory processing of self-generated signals along a fast electrosensory pathway in electric fish. Previous results indicate that the spherical neuron's intrinsic properties depend mainly on the presence of two resonant currents that tend to clamp the voltage near the resting potential. ⋯ We also show that the low-threshold potassium current also causes the long refractory period, explaining the necessary properties that implement the dynamic filtering of the self-generated signals previously described. Comparative data from other fish and from the auditory system indicate that other single spiking onset neurons might differ in the channel repertoire observed in the spherical neurons of Gymnotus omarorum.
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Neuromedin U (NMU) is a highly conserved neuropeptide which regulates food intake and body weight. Transgenic mice lacking NMU are hyperphagic and obese, making NMU a novel target for understanding and treating obesity. Neuromedin U receptor 2 (NMUR2) is a high-affinity receptor for NMU found in discrete regions of the central nervous system, in particular the paraventricular nucleus of the hypothalamus (PVN), where it may be responsible for mediating the anorectic effects of NMU. ⋯ However, when the same rats were fed a high-fat diet (45% fat), they consumed significantly more food, gained more body weight, and had increased feed efficiency relative to controls. Furthermore, NMUR2 knockdown rats demonstrated significantly greater binge-type food consumption of the high-fat diet and showed a greater preference for higher-fat food. These results demonstrate that NMUR2 signaling in the PVN regulates consumption and preference for high-fat foods without disrupting feeding behavior associated with non-obesogenic standard chow.
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Death-associated protein kinase (DAPK) has been found promoting cell death under stress conditions, including cell death during brain ischemia. However, little is known about the mechanisms how DAPK is involved in the neuronal death-promoting process during ischemia. The present study was to examine the DAPK signal transduction pathways using an ischemia mimicking model, oxygen glucose deprivation (OGD). ⋯ The activation of DAPK in turn led to BimEL up-regulation and endoplasmic reticulum (ER) stress activation. Further analyses showed that DAPK mediated BimEL expression through extracellular signal-regulated protein kinase1/2 (ERK1/2) inactivation and c-Jun-N-terminal kinase1/2 (JNK1/2) activation. These findings revealed novel signal transduction pathways leading to neuronal death in response to OGD.
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It has been argued that arm movements are important during human gait because they affect leg activity due to neural coupling between arms and legs. Consequently, one would expect that locomotor-like alternating arm swing is more effective than in-phase swing in affecting the legs' motor output. Other alternating movements such as trunk rotation associated to arm swing could also affect leg reflexes. ⋯ Furthermore, this modulation was independent from electromyographic activity, suggesting a spinal processing at premotoneuronal level. Therefore, trunk movement can affect legs' output, and a special neural coupling occurs between arms and legs when arms move in alternation. This may have implications for gait rehabilitation.
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Recently we demonstrated that it is possible to influence tactile perception by applying a placebo manipulation consisting of verbal suggestion and conditioning and that this influence is associated to changes in the late components (N140 and P200) of somatosensory-evoked potentials (SEPs) (Fiorio et al., 2012). Due to the powerful effects of words in changing symptoms perception in the clinical domain, aim of this study was to investigate whether even in the tactile modality, perception can be changed by the mere use of persuasive words in a specific context. To this purpose, we adopted the same experimental setting of our previous study, apart from the conditioning procedure. ⋯ Results showed that the experimental group did not perceive an increase of tactile sensation after the treatment and no modification occurred in the late SEPs. This study proves that verbal suggestion alone is not sufficient to induce enhanced tactile perception (at least with this experimental setting), suggesting that a conditioning procedure may be necessary in the tactile modality. The absence of changes in the late SEP components could reflect the lack of strong expectation following the placebo procedure.