Journal of neuroscience methods
-
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.
-
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.