Neuroscience
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Little is known about the neural mechanisms that mediate differential action-selection responses to communication and echolocation calls in bats. For example, in the big brown bat, frequency modulated (FM) food-claiming communication calls closely resemble FM echolocation calls, which guide social and orienting behaviors, respectively. ⋯ We combined information obtained from spike number and spike triggered averages (STA) to reveal a robust classification of neuron selectivity for communication or echolocation calls. These data highlight the importance of temporal acoustic structure for differentiating echolocation and food-claiming social calls and point to general mechanisms of natural sound processing across species.
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Recently, alterations of complexity due to brain disorders have been demonstrated using brain entropy (BEN), while the changes of brain complexity in stroke, a common cerebrovascular disease, remain unclear. In this research, resting-state functional magnetic resonance imaging (fMRI) was performed to explore the alterations of brain complexity using BEN in twenty stroke patients with motor deficits and nineteen matched healthy controls. The sample entropy (SampEn) was applied to build the BEN mapping for each participant. ⋯ Moreover, significantly positive correlations between BEN values and Fugl-Meyer Assessment scores were detected in the ipsilesional SFGdor and ipsilesional SMA. Mutual information independence was observed between BEN and regional homogeneity (ReHo), amplitude of low-frequency fluctuations (ALFF), respectively, in the stroke patients. Our findings implied that brain complexity had been impacted after stroke, and also suggested that BEN could be a complementary tool for evaluating the motor impairment after stroke.
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The growing presence of artificial lighting across the globe presents a number of challenges to human and ecological health despite its societal benefits. Exposure to artificial light at night, a seemingly innocuous aspect of modern life, disrupts behavior and physiological functions. Specifically, light at night induces neuroinflammation, which is implicated in neuropathic and nociceptive pain states, including hyperalgesia and allodynia. ⋯ Altered nociception in mice exposed to dim light at night was concurrent with upregulated interleukin-6 and nerve growth factor mRNA expression in the medulla and elevated μ-opioid receptor mRNA expression in the periaqueductal gray region of the brain. The current results support the relationship between disrupted circadian rhythms and altered pain sensitivity. In summary, we observed that dim light at night induces cold hyperalgesia and mechanical allodynia, potentially through elevated neuroinflammation and dysregulation of the endogenous opioid system.
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Object prehension typically includes a transport phase (reaching) and a grip phase (grasping). Within the posterior parietal cortex (PPC), grasping movements have been traditionally associated to a lateral activation, although recent monkey evidence suggests also a medial involvement. Here, we wanted to determine whether grasping-related activities are present in the human dorsomedial parietal cortex, by focusing on two cortical regions specialized in the monkey in controlling limb movements, i.e., V6A (composed by its ventral and dorsal sectors, V6Av and V6Ad, respectively) and PEc, both recently defined also in humans. ⋯ We found that the human areas V6Ad (hV6Ad) and PEc (hPEc) were both activated by real grasping, whereas hV6Ad only was activated by the imagery of grasping movements. hV6Av was not involved in either types of grasping. These results speak against the traditional notion of a medial-to-lateral segregation of reaching versus grasping information within the PPC and strengthen the idea that the human dorsomedial parietal cortex implements the whole complex pattern of visuomotor transformations required for object-oriented actions. Our findings suggest that hV6Ad is particularly involved in implementing all the visuomotor transformations needed to create an abstract representation of the object-directed action, while hPEc is involved in implementing the sensorimotor transformations needed to actually perform that action.
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Individuals with pain report higher sensory disturbances during sensorimotor conflicts compared to pain-free individuals. In the pain field, it is frequently assumed that disturbances arise from a discordance between sensory and efference copies (defined as sensory-motor conflict), while in the sensorimotor control field they are considered to result from the incongruence between sensory modalities (defined as sensory-sensory conflict). The general aim of this study was to disentangle the relative contribution of motor efferences and sensory afferences to the increased sensitivity to sensorimotor conflicts in individual with fibromyalgia (n = 20) compared to controls (n = 20). ⋯ Moreover, the increase in conflict sensitivity from sensory-sensory to sensory-motor conflicts in fibromyalgia was related to conflict-induced motor disturbances (r = 0.57; p < 0.01), but did not result from a poorer proprioception (r = 0.12; p = 0.61). Therefore, it appears that higher conflict sensitivity in fibromyalgia is mainly explained by a sensory-motor conflict rather by a sensory-sensory conflict. We suggest this arises due to a deficit in updating predicted sensory feedback rather than in selecting appropriate motor commands.