Neuroreport
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This study examined the effects of pulsed radiofrequency (PRF) on sciatic nerve ligation-induced mechanical pain hypersensitivity in rats. The nociceptive threshold was evaluated using the paw pressure vocalization test. ⋯ One day after PRF, the effect of morphine (2 mg/kg, subcutaneous) increased the nociceptive threshold in the no PRF/CCI group and more extensively in PRF/CCI animals. These results showed that PRF might represent an interesting strategy not only to reduce neuropathic pain but also to enhance the efficacy of morphine in patients with neuropathic pain, well known to be opioid resistant.
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TRPV1 is a nonselective cation channel in nociceptors. TRPV1 stimulation has been shown to lead to the activation of microglia and astrocytes in the dorsal horn of the spinal cord. However, information on the effect of TRPV1 stimulation on glial activation in the trigeminal nucleus caudalis (TNC) is lacking. ⋯ The ratio of the cross-sectional area immunoreactive for glial fibrillary acidic protein to the entire TNC showed a significant increase in d2 group and the d4 group compared with the c group on the injected side. Behavioral analysis indicated that mechanical allodynia began to develop after 2 days of capsaicin treatment and persisted for at least 6 days after the onset of the repetitive capsaicin injection. These data indicate that TRPV1 stimulation activates the microglia and astrocytes in temporally distinct ways and that the development of mechanical allodynia is independent of such glial activation.
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A potential threat, such as a spider, captures attention and engages executive functions to adjust ongoing behavior and avoid danger. We and many others have reported slowed responses to neutral targets in the context of emotional distractors. This behavioral slowing has been explained in the framework of attentional competition for limited resources with emotional stimuli prioritized. ⋯ The results fit in the framework of the resource competition model. A potential threat calls for evaluation of affective significance as well as inhibition of undue emotional reactivity. We suggest that these functions tax executive resources and may render other executive functions, such as response inhibition, temporarily compromised when the demands for resources exceed availability.
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Thalamocortical networks play an important role in information integration during consciousness. However, little is known about how the information flows between the thalamus and the cortex are affected by a loss of consciousness. To investigate this issue, we analyzed effective connectivity between the cortex and the thalamus in animals during anesthesia-induced transitions. ⋯ Specifically, the effective connectivity between the cortex and the ventral lateral thalamus was altered such that the primary motor and the primary somatosensory cortex Granger-caused the ventral lateral thalamus before loss of consciousness whereas the ventral lateral thalamus Granger-caused the primary motor cortex and the primary somatosensory cortex after loss of consciousness. In contrast, the primary somatosensory cortex consistently Granger-caused the ventrobasal thalamus, regardless of the loss of consciousness. These results suggest how information flows change across the thalamocortical network during transitions in consciousness.
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High-frequency deep brain stimulation targeting the output nucleus of the basal ganglia, the globus pallidus internus, has been suggested as a treatment modality for intractable Tourette syndrome and basal-ganglia-mediated motor tics. Recent studies on the modeling of motor tics induced by focal injections of bicuculline to the striatum, a putative model of Tourette syndrome, have shown that tics induce a widespread modulation within both segments of the globus pallidus. ⋯ The results showed that the stimulation blocked tic-related phasic changes in the firing pattern of pallidal cells in parallel with a reduction of the peak amplitude of tic events in the electromyography record. This finding supports the premise that deep brain stimulation targeted to the globus pallidus internus could be a viable treatment option for Tourette syndrome, and the use of pallidal stimulation for motor tics warrants further study.