Neuroscience
-
Spatial relations (SRs: coordinate/metric vs categorical/non metric) and frames of reference (FoRs: egocentric/body vs allocentric/external element) represent the building blocks underlying any spatial representation. In the present 7-T fMRI study we have identified for the first time the neural correlates of the spatial representations emerging from the combination of the two dimensions. The direct comparison between the different spatial representations revealed a bilateral fronto-parietal network, mainly right sided, that was more involved in the egocentric categorical representations. ⋯ Finally, a smaller part of this bilateral network (i.e. Calcarine Sulcus and Lingual Gyrus), along with the right Supramarginal and Inferior Frontal gyri, supported the allocentric coordinate representations. The fact that some areas were more involved in a spatial representation than in others reveals how our brain builds adaptive spatial representations in order to effectively react to specific environmental needs and task demands.
-
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by selective loss of motor neurons. Statins are widely used as cholesterol-lowering drugs and significantly reduce the risk of cardiovascular and cerebrovascular diseases. Increasing evidence indicates the protective effects of statins against certain neurodegenerative diseases. ⋯ Conversely, these outcomes were completely reversed by co-incubation with mevalonate, farnesyl pyrophosphate (FPP) or geranylgeranyl pyrophosphate (GGPP) but not cholesterol. In addition, inhibition of geranylgeranyl transferase I by GGTI-286 led to similar alterations in cell viability and autophagic marker levels. These results indicated that the cytotoxic effect of simvastatin on NSC34-hSOD1G93A cells might be due to the aggravation of autophagic flux impairment through the inhibition of GGPP synthesis.
-
Benzodiazepines are one of the most commonly prescribed anxiolytic drugs in America, and between 2006 and 2015 prescription rates increased by an estimated 27.1%. Weight gain is a common side effect of these drugs and it may result from increased feeding caused by drug-enhanced food palatability. We investigated the role of specific GABAA receptor subtypes involved with benzodiazepine-induced food consumption through third ventricle injections of L-838,417, a partial agonist of GABAA α2, α3, and α5 subunits, and a full antagonist of the α1 receptor subunit. ⋯ These results indicate that nuclei in proximity to the ventricles respond to GABAA α2, α3, or α5 activation to induce motivation to feed, absent of α1 receptor subunit activation. Furthermore, activation of the α1 subunit is not necessary for benzodiazepine hyperphagia and may instead contribute to the oromotor depressant and sedative properties of classic benzodiazepine agonists. Hypothalamic nuclei such as the paraventricular nucleus may be involved in the benzodiazepine-increased motivation to feed, while the parabrachial nucleus of the hindbrain could contribute to benzodiazepine-induced enhancement of taste palatability.
-
Estrogen receptor-alpha (ERα) and -beta (ERβ) occur in key elements of the brain gluco-homeostatic network in both sexes, including the hindbrain dorsal vagal complex (DVC), but the influence of distinct receptor populations on this critical function is unclear. The ventromedial hypothalamic nucleus (VMN) maintains glucose balance by integrating nutrient, endocrine, and neurochemical cues, including metabolic sensory information supplied by DVC A2 noradrenergic neurons. Current research utilized the selective ERα and ERβ antagonists MPP and PHTPP to characterize effects of DVC ERs on VMN norepinephrine (NE) activity and metabolic neurotransmitter signaling in insulin-induced hypoglycemic (IIH) male rats. ⋯ Both ERs regulate corticosterone, but not glucagon secretion during IIH and oppose hypoglycemic diminution of circulating free fatty acids. These findings identify distinguishing versus common VMN functions targeted by DVC ERα and -β. Sex differences in hypoglycemic VMN NE accumulation, glycogen metabolism, and transmitter signaling may involve, in part, discrepant regulatory involvement or differential magnitude of impact of these hindbrain ERs.
-
The ability to track multiple objects is important for daily life activities such as driving, but it is subject to some restrictions. One limitation concerns the hemifields in which objects move. A previous study showed that when subjects were restricted to the use of one hemifield, both the maximum number of tracked objects and the tracking accuracy were lower than when they were permitted to use both hemifields. ⋯ In the SSVEP experiment, SSVEP amplitudes for target and distractor frequencies differed under the Within condition but did not differ under the Crossover condition. However, phase synchronization between the left and right hemifields exhibited the opposite trend. This study provides evidence that attention to objects moving between hemifields is suppressed relative to attention to objects moving within hemifields and that Crossover tracking diminishes attentional modulation at an early sensory processing level while modulating interhemispheric functional connectivity.