Neuroscience letters
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Neuroscience letters · May 2004
Selective C-fiber deafferentation of the spinal dorsal horn prevents lesion-induced transganglionic transport of choleragenoid to the substantia gelatinosa in the rat.
The effect of neonatal capsaicin treatment, producing selective elimination of almost all unmyelinated C-fiber sensory axons, was studied on lesion-induced transganglionic labelling of the substantia gelatinosa of the spinal cord by choleragenoid. In both control and capsaicin-pretreated rats, the injection of choleragenoid-horseradish peroxidase conjugate into the intact sciatic nerves resulted in intense labelling only of the deeper layers of the spinal dorsal horn. In the control but not the capsaicin-pretreated rats, the injection of the tracer into sciatic nerves transected 2 weeks previously produced an intense homogeneous labelling of the substantia gelatinosa. It is concluded that the uptake and axonal transport of choleragenoid by capsaicin-sensitive C-fiber afferents may be accounted for by the lesion-induced transganglionic labelling of the substantia gelatinosa, rather than by A-fiber sprouting.
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Neuroscience letters · May 2004
Single-trial detection of human brain responses evoked by laser activation of Adelta-nociceptors using the wavelet transform of EEG epochs.
The aim of this study was to identify EEG changes induced by Adelta-nociceptor activation in single trials. In a preliminary experiment, intense CO(2) laser stimuli were delivered to the hand dorsum of five volunteers. The average amplitude of EEG epochs was estimated in the time-frequency (TF) domain using the continuous Morlet wavelet transform (CMT). ⋯ After applying the TF filter, amplitudes within a predefined interval were summed. Whether this sum predicted the occurrence of Adelta-nociceptor activation was tested using the reaction-time to discriminate between Adelta- or C-fibre mediated detection. Results showed that this method accurately identified single-trial EEG responses to Adelta-nociceptor activation.
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Neuroscience letters · May 2004
Longterm stability and developmental changes in spontaneous network burst firing patterns in dissociated rat cerebral cortex cell cultures on multielectrode arrays.
Spontaneous action potentials were recorded longitudinally for 4-7 weeks from dissociated rat occipital cortex cells cultured on planar multi-electrode plates, during their development from isolated neurons into synaptically connected neuronal networks. Activity typically consisted of generalized bursts lasting up to several seconds, separated by variable epochs of sporadic firing at some of the active sites. ⋯ These findings indicate that after about a month in vitro these cultured neuronal networks have developed a degree of excitability that allows almost instantaneous triggering of generalized discharges. Individual neurons tend to fire in specific and persistent temporal relationships to one another within these network bursts, suggesting that network connectivity maintains a core topology during its development.
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Neuroscience letters · May 2004
Synaptic plasticity in the amygdala in a visceral pain model in rats.
The amygdala plays a key role in the emotional-affective component of pain. This study is the first to analyze synaptic plasticity in the central nucleus of the amygdala (CeA) in a model of visceral pain. Whole-cell patch-clamp recordings were made from neurons in the latero-capsular part of the CeA in brain slices from control rats and rats with zymosan-induced colitis (>6 h postinduction). ⋯ Enhanced synaptic transmission was observed at the nociceptive PB-CeA synapse, but not at the polymodal BLA-CeA synapse, in rats with colitis. The frequency of action potentials evoked by direct current injection was increased in CeA neurons from colitis rats, suggesting enhanced neuronal excitability. Our results provide novel evidence for an important role of the CeA in visceral pain.
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Neuroscience letters · Apr 2004
Comparative StudyMuscle-specific protein MDP77 specifically promotes motor nerve regeneration in rats.
This study has examined the effects of recombinant human MDP77 (rhMDP77) on sciatic motor nerve regeneration in vivo. We carried out bridge grafting (14 mm) into the sciatic nerve of Sprague-Dawley rats using silicone tubes containing a mixture of type-I collagen and 0, 5, 10, or 20 microg/ml of rhMDP77, or containing phosphate-buffered solution (N = 6 in each group). Electrophysiological and histological evaluations carried out 12 weeks after implantation suggest that rhMDP77 has a positive effect on terminal and collateral sprouting of regenerating nerves and thereby promotes motor nerve regeneration in a dose-dependent manner.