Neuroscience
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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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It was the aim of the present study to investigate menstrual cycle effects on selective attention and its underlying functional cerebral networks. Twenty-one healthy, right-handed, normally cycling women were investigated by means of functional magnetic resonance imaging using a go/no-go paradigm during the menstrual, follicular and luteal phase. On the behavioral level there was a significant interaction between visual half field and cycle phase with reaction times to right-sided compared to left-sided stimuli being faster in the menstrual compared to the follicular phase. ⋯ Functional imaging, however, did not reveal clear-cut menstrual phase-related changes in activation pattern in parallel to these behavioral findings. A functional connectivity analysis identified differences between the menstrual and the luteal phase: During the menstrual phase, left inferior parietal cortex showed a stronger negative correlation with the right middle frontal gyrus while the left medial frontal cortex showed a stronger negative correlation with the left middle frontal gyrus. These results can serve as further evidence of a modulatory effect of steroid hormones on networks of lateralized cognitive functions not only by interhemispheric inhibition but also by affecting intrahemispheric functional connectivity.
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Although it is a general consensus that opioids modulate growth, the mechanism of this phenomenon is largely unknown. Since endogenous opiates use the same receptor family as morphine, these peptides may be one of the key regulators of growth in humans by impacting growth hormone (GH) secretion, either directly, or indirectly, via growth hormone-releasing hormone (GHRH) release. However, the exact mechanism of this regulation has not been elucidated yet. ⋯ In contrast, no significant dynorphinergic-GHRH associations were detected. The density of the abutting enkephalinergic fibers on the surface of the GHRH perikarya suggests that these juxtapositions may be functional synapses and may represent the morphological substrate of the impact of enkephalin on growth. The small number of GHRH neurons innervated by the endorphin and dynorphin systems indicates significant differences between the regulatory roles of endogenous opiates on growth in humans.
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Previous research has demonstrated that diabetes induces learning and memory deficits. However, the mechanism of memory impairment induced by diabetes is poorly understood. Dietary fatty acids, especially polyunsaturated fatty acids, have been shown to enhance learning and memory and prevent memory deficits in various experimental conditions. ⋯ STZ-induced diabetes impaired spatial learning and memory of rats, which was associated with the inflammation, oxidative stress and apoptosis of hippocampal neurons. Fish oil administration ameliorated cognitive deficit, reduced oxidative stress and tumor necrosis factor α (TNF-α), protected the hippocampal neurons by increasing Protein Kinase B (AKT) phosphorylation and decreasing caspase-9 expression. These results suggested that the principle mechanisms involved in the antidiabetic and neuroprotective effect of fish oil were its antioxidant, anti-inflammatory and anti-apoptosis potential, supporting a potential role for fish oil as an adjuvant therapy for the prevention and treatment of diabetic complications.
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The rat retrotrapezoid nucleus (RTN) contains neurons that have a well-defined phenotype characterized by the presence of vesicular glutamate transporter 2 (VGLUT2) mRNA and a paired-like homeobox 2b (Phox2b)-immunoreactive (ir) nucleus and the absence of tyrosine hydroxylase (TH). These neurons are important to chemoreception. In the present study, we tested the hypothesis that the chemically-coded RTN neurons (ccRTN) (Phox2b(+)/TH(-)) are activated during an acute episode of running exercise. ⋯ Also the retrograde tracer Fluoro-Gold that was injected into RTN was detected in c-Fos-ir PeF/LH (p<0.05). In summary, the ccRTN neurons (Phox2b(+)TH(-)) are excited by running exercise. Thus, ccRTN neurons may contribute to both the chemical drive to breath and the feed-forward control of breathing associated with exercise.