Neuroscience
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Some models of motivation distinguish between intrinsic and extrinsic motivation. While past work has examined the neural and cognitive correlates of extrinsic motivation, research on intrinsic motivation has relied primarily on behavioral measures of performance and learning. In particular, no past work has examined the neural and cognitive correlates of social performance expectancy, which is linked to intrinsic motivation. ⋯ EEG was used to examine motor-action preparation as measured by suppression of beta band activity over the motor cortex and feedback processing as measured by the Reward Positivity (RewP). Results revealed expectancy of difficult (vs. easy) trials narrowed attentional scope, reduced beta activity over the motor cortex, and enhanced RewP amplitudes to win feedback. These findings suggest that enhancing intrinsic motivation through expectancies of positive social comparison engages similar neural and cognitive correlates as extrinsic motivators high in motivational intensity.
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The great majority of neurons in the superficial dorsal horn of the spinal cord are excitatory interneurons, and these are required for the normal perception of pain and itch. We have previously identified 5 largely non-overlapping populations among these cells, based on the expression of four different neuropeptides (cholecystokinin, neurotensin, neurokinin B and substance P) and of green fluorescent protein driven by the promoter for gastrin-releasing peptide (GRP) in a transgenic mouse line. Another peptide (neuropeptide FF, NPFF) has been identified among the excitatory neurons, and here we have used an antibody against the NPFF precursor (pro-NPFF) and a probe that recognises Npff mRNA to identify and characterise these cells. ⋯ By examining phosphorylation of extracellular signal-regulated kinases, we show that the NPFF cells can respond to different types of noxious and pruritic stimulus. Ablation of somatostatin-expressing dorsal horn neurons has been shown to result in a dramatic reduction in mechanical pain sensitivity, while somatostatin released from these neurons is thought to contribute to itch. Since the great majority of the NPFF cells co-expressed somatostatin, these cells may play a role in the perception of pain and itch.
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Diabetes is a chronic degenerative disease that represent a major threat to public health worldwide. Once the disease is established, one of the major concerns about the diabetes complications is the development of neuropathy. This study established an experimental model that evaluates the effect of type 1 diabetes on nociceptive challenges in the temporomandibular joint (TMJ). ⋯ Diabetic animals pre-treated with Protein Kinase C (PKC)-α and -β inhibitor (GO6976) or PKC-β inhibitor (LY333531) significantly increased capsaicin-induced nociception in the TMJ higher protein levels of Na+/K+-ATPase pump in the trigeminal ganglia. On the other hand, although diabetes inhibits formalin-induced nociception higher protein levels of pro-inflammatory cytokine IL1-β and chemokine CINC-1/CXCL-1 were observed. Overall, the results of the present work suggest that diabetes causes a hyporesponsiveness of C-fiber and a potentialization of the inflammatory response which may result in the degenerative process of periarticular tissues without pain perception.
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Impaired finger motor function in post-stroke hemiplegia is a debilitating condition with no evidence-based or accessible treatments. Here, we evaluated the neurophysiological effectiveness of direct brain control of robotic exoskeleton that provides movement support contingent with brain activity. To elucidate the mechanisms underlying the neurofeedback intervention, we assessed resting-state functional connectivity with functional magnetic resonance imaging (rsfcMRI) between the ipsilesional sensory and motor cortices before and after a single 1-h intervention. ⋯ Although the neurofeedback intervention delivered fewer total sensorimotor stimulations compared to the sham-control, rsfcMRI in the ipsilesional sensorimotor cortices was increased during the neurofeedback intervention compared to the sham-control. Higher coactivation of the sensory and motor cortices during neurofeedback intervention enhanced rsfcMRI in the ipsilesional sensorimotor cortices. This study showed neurophysiological evidence that EEG-contingent neurofeedback is a promising strategy to induce intrinsic ipsilesional sensorimotor reorganization, supporting the importance of integrating closed-loop sensorimotor processing at a neurophysiological level.
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Humans can recognize living organisms and understand their actions solely on the basis of a small animated set of well-positioned points of light, i.e. by recognizing biological motion. Our aim was to determine whether this type of recognition and integration also occurs during the perception of one's own movements. The participants (60 females) were immersed with a virtual reality headset in a virtual environment, either dark or illuminated, in which they could see a humanoid avatar from a first-person perspective. ⋯ Kinesthetic illusions also occurred with point-light avatars, albeit less frequently and a little less intense, and only when the visual environment was optimal for slow motion detection of the point-light display (lit environment). We conclude that kinesthesia does not require visual access to an elaborate representation of a body segment. Access to biological movement can be sufficient.