Journal of neuroscience methods
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J. Neurosci. Methods · Aug 2004
Comparative StudyOver-pulsing degrades activated iridium oxide films used for intracortical neural stimulation.
Microelectrodes using activated iridium oxide (AIROF) charge-injection coatings have been pulsed in cat cortex at levels from near-threshold for neural excitation to the reported in vitro electrochemical charge-injection limits of AIROF. The microelectrodes were subjected to continuous biphasic current pulsing, using an 0.4V (versus Ag|AgCl) anodic bias with equal cathodal and anodal pulse widths, for periods up to 7h at a frequency of either 50Hz or 100Hz. ⋯ AIROF microelectrodes challenged in vitro under the same pulsing conditions responded similarly, with electrodes pulsed at 3mC/cm(2) showing evidence of AIROF delamination after only 100s of pulsing at 100Hz (10,000 pulses total), while electrodes pulsed at 2mC/cm(2) for 7h at 50Hz (1.3 x 10(6) pulses total) showed no evidence of damage. In vitro electrochemical potential transient measurements in buffered physiologic saline indicate that polarizing the AIROF beyond the potential window for electrolysis of water (-0.6 to 0.8V versus Ag|AgCl) results in the observed degradation.
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J. Neurosci. Methods · Aug 2004
Comparative StudyA novel rodent neck pain model of facet-mediated behavioral hypersensitivity: implications for persistent pain and whiplash injury.
Clinical, epidemiological, and biomechanical studies suggest involvement of cervical facet joint injuries in neck pain. While bony motions can cause injurious tensile facet joint loading, it remains speculative whether such injuries initiate pain. There is currently a paucity of data explicitly investigating the relationship between facet mechanics and pain physiology. ⋯ Findings demonstrate tensile facet joint loading produces behavioral sensitivity that varies in magnitude according to injury severity. These results suggest that a facet joint tensile strain threshold may exist above which pain symptoms result. Continued investigation into the relationship between injury mechanics and nociceptive physiology will strengthen insight into painful facet injury mechanisms.
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J. Neurosci. Methods · Jul 2004
A new method for the extraction and classification of single motor unit action potentials from surface EMG signals.
It has been shown that multi-channel surface EMG allows assessment of anatomical and physiological single motor unit (MU) properties. To get this information, the action potentials of single MUs should be extracted from the interference EMG signals. This study describes an automatic system for the detection and classification of MU action potentials from multi-channel surface EMG signals. ⋯ Thus, the proposed algorithm was able to identify a MU sample representative of the muscle. Results on experimental signals recorded from different muscles and conditions are reported, showing the possibility of investigating anatomical and physiological properties of the detected MUs in a variety of practical cases. The main limitation of the approach is that complete firing patterns can be obtained only in specific cases due to MU action potential superpositions.
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J. Neurosci. Methods · Jun 2004
A computational tool to simulate correlated activity in neural circuits.
A new computational approach to study correlated neural activity is presented. Simulating Elementary Neural NEtworks for Correlation Analysis (SENNECA) is a specific-purpose simulator oriented to small circuits of realistic neurons. ⋯ Three different distributions of SENNECA are available: an easy-to-use web-based version, a Matlab (Windows and Linux) script, and a C++ class library for low-level coding. The main features of the simulator are explained, and several examples of neural activity analysis are given to illustrate the potential of this new tool.
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J. Neurosci. Methods · Jun 2004
Comparative StudyHistopathological and behavioral characterization of a novel model of cardiac arrest and cardiopulmonary resuscitation in mice.
Cardiac arrest is associated with high mortality and poor neurological outcome. We characterized functional and histological outcome in a novel mouse model of cardiac arrest and cardiopulmonary resuscitation (CPR) in order to study neuroprotective mechanisms. Cardiac arrest was induced in male C57Bl/6 and 129SVEV mice by i.v. injection of KCl. ⋯ Post-ischemic mice of both strains showed a reduced number of correct choices in the T-maze up to 7 days after CPR, and were temporarily impaired in learning the passive avoidance task with a retention deficit on day 3 but not on day 7. Locomotor activity showed strain differences with C57Bl/6 mice being more active, but little ischemia-related effects. A dissociation between functional and histological outcome was found emphasizing the importance of combining both outcome measures for evaluation of neuroprotective strategies.