Neuroscience
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Clinical evidences suggest that an imbalance between descending inhibition and facilitation drives the development of chronic pain. However, potential mechanisms promoting the establishment of a persistent pain state and the increased pain vulnerability remain unknown. This preclinical study was designed to evaluate temporal changes in descending pain modulation at specific experimental endpoints (12, 28, 90 and 168days) using a novel double-hit model of chronic/tonic pain (first hit: chronic constriction injury (CCI) model; second hit: tonic formalin pain in the contralateral hindpaw). ⋯ These molecular and behavioral adaptive changes in descending pain inhibition seemed to slowly fade over time. We therefore suggest that chronic neuropathic pain produces a transient hyperactivation of bulbo-spinal monoaminergic drive when previously primed using a tonic pain paradigm (i.e., formalin test), translating into inhibition of subsequent nociceptive behaviors. Altogether, we propose that early hyperactivation of descending pain inhibitory mechanisms, and its potential ensuing exhaustion, could be part of the temporal neurophysiological chain of events favoring chronic neuropathic pain establishment.
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The aims of this study were to use functional magnetic resonance imaging to examine the neural bases for perceptual-cognitive superiority in a hockey anticipation task. Thirty participants (15 hockey players, 15 non-hockey players) lay in an MRI scanner while performing a video-based task in which they predicted the direction of an oncoming shot in either a hockey or a badminton scenario. Video clips were temporally occluded either 160ms before the shot was made or 60ms after the ball/shuttle left the stick/racquet. ⋯ The imaging data on the other hand showed a significant main effect of hockey expertise and of video type (hockey vs. badminton), but the expertise×video-type interaction did not survive either a whole-brain or a small-volume correction for multiple comparisons. Further analysis of the expertise main effect revealed that when watching hockey clips, experts showed greater activation in the rostral inferior parietal lobule, which has been associated with an action observation network, and greater activation than novices in Brodmann areas 17 and 18 and middle frontal gyrus when watching badminton videos. The results provide partial support both for domain-specific and domain-general expertise effects in an action anticipation task.
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Temporal lobe epilepsy (TLE) is one of the most common neurologic disorders often associated with behavioral impairments and cognitive deficit. Lithium-pilocarpine model of seizures in rodents reproduces many features of human convulsive status epilepticus (SE) and subsequent TLE. In this study, we have investigated changes in the rat brain after lithium-pilocarpine SE using a high-field MRI system for small animals in early and chronic periods after SE. ⋯ Rats survived after SE showed locomotor hyperactivity and disruption of long-term habituation in the open field test carried out 5weeks after the seizures. Interestingly, T2 in the amygdala 30days after SE had a strong correlation with hyperactivity in the novel open field. Therefore, the amygdala damage may be an important factor in the development of hyperactivity in the chronic period after SE.
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Recent studies have suggested that both configural information, such as face shape, and surface information is important for face perception. In particular, facial color is sufficiently suggestive of emotional states, as in the phrases: "flushed with anger" and "pale with fear." However, few studies have examined the relationship between facial color and emotional expression. On the other hand, event-related potential (ERP) studies have shown that emotional expressions, such as fear, are processed unconsciously. ⋯ The results indicated that there was a significant interaction between facial expression and color for the latency of the N170 component. Subsequent analyses revealed that the bluish-colored faces increased the latency effect of facial expressions compared to the natural-colored faces, indicating that the bluish color modulated the processing of fearful expressions. We conclude that the unconscious processing of fearful faces is affected by facial color.
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The medial preoptic nucleus (MPN) is a sexually dimorphic cell group of the medial preoptic area that plays a central role in the integration of olfactory and hormonal stimuli that modulate sexually differentiated behaviors. The influence of sex steroids in these behaviors is mediated through activation of estrogen receptors (ERs), which are highly expressed in this nucleus. Little is known about the effects of progesterone (P) or the selective activation of each ER subtype on the expression of estrogen receptor alpha (ERα) in the MPN of female rats. ⋯ A similar effect was observed after the administration of EB, but not of P. Results also show that the estradiol-induced down-regulation of the ERα is mediated by activation of both ER subtypes, and that ERβ activation leads to a reduction in the total number of ERα-immunoreactive neurons that is twice that resulting from ERα activation. Present data suggest that ERα activation triggers a sort of negative feedback mechanism in MPN neurons that reduces its own expression, which might be of importance for the regulation of estradiol-dependent physiological and behavioral responses.