Neuroscience letters
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The 'thermal grill illusion' refers to paradoxical sensations of heat and pain, resulting from simultaneous application of interlaced warm and cold stimuli to the skin. It provides an interesting model of integrative mechanisms in the nervous system, supposed to be relevant in explaining the hypersensitivity found in chronic pain of unclear etiology. The aim of this study is to investigate the perceptual qualities elicited by a reconstruction of the original grill stimulator and to compare these qualities with those elicited by a single temperature thermode of identical dimensions. ⋯ Pain-related sensations were less present in the grill percept than in a single hot stimulus near pain threshold. The spectrum of qualities of the grill stimulus changed marginally with stimulus duration by decrease of a cold component and concurrent increase of a heat component. In conclusion, the percept of the thermal grill is not simply pain--it can be understood as a metaesthetic percept at the transition from heat to pain.
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Neuroscience letters · Nov 2011
Neuregulin-1 prevents amyloid β-induced impairment of long-term potentiation in hippocampal slices via ErbB4.
Neuregulin-1 (NRG1) participates in numerous neurodevelopmental processes and plasticity of the brain. Despite this, little is known about its role in Alzheimer's disease (AD). Amyloid β (Aβ) peptide is generally believed to play a critical role in the pathogenesis of AD. ⋯ Pretreatment with NRG1 effectively prevented Aβ₁₋₄₂-induced impairment of LTP, an effect that was dose-dependent. This LTP-restoring action of NRG1 was almost completely abolished by blocking ErbB4, a key NRG1 receptor, suggesting that NRG1 acts through ErbB4 to exert its protective action on LTP. The present study thus provides the first demonstration that NRG1/ErbB4 protects against Aβ-induced hippocampal LTP impairment, suggesting that NRG1 may be a promising candidate for the treatment of early-stage AD.
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Neuroscience letters · Nov 2011
Electrical stimulation at distinct peripheral sites in spinal nerve injured rats leads to different afferent activation profiles.
The neurophysiological basis by which neuromodulatory techniques lead to relief of neuropathic pain remains unclear. We investigated whether electrical stimulation at different peripheral sites induces unique profiles of A-fiber afferent activation in nerve-injured rats. At 4-6weeks after subjecting rats to L5 spinal nerve injury (SNL) or sham operation, we recorded the orthodromic compound action potential (AP) at the ipsilateral L4 dorsal root in response to (1) transcutaneous electrical nerve stimulation (TENS, a patch electrode placed on the dorsum of the foot), (2) subcutaneous electrical stimulation (SQS, electrode inserted subcutaneously along the dorsum of the foot), (3) peroneal nerve stimulation (PNS, electrode placed longitudinally abutting the nerve), and (4) sciatic nerve stimulation (SNS). ⋯ The Aα/β-threshold to PNS was higher in the SNL group than in the sham-operated group. The S-R functions and Aα/β-thresholds to TENS and SQS were comparable between the two groups. Electrical stimulation of different peripheral targets induced distinctive profiles of A-fiber afferent activation, suggesting that the neuronal substrates for the various forms of peripheral neuromodulatory therapies may differ.