High efficient electrical stimulation of hippocampal slices with vertically aligned carbon nanofiber microbrush array

Long-term neuroprostheses for functional electrical stimulation must efficiently stimulate tissue without electrolyzing water and raising the extracellular pH to toxic levels. Comparison of the stimulation efficiency of tungsten wire electrodes (W wires), platinum microelectrode arrays (PtMEA), as-grown vertically aligned carbon nanofiber microbrush arrays (VACNF MBAs), and polypyrrole coated (PPy-coated) VACNF MBAs in eliciting field potentials in the hippocampus slice indicates that, at low stimulating voltages that preclude the electrolysis of water, only the PPy-coated VACNF MBA is able to stimulate the CA3 to CA1 pathway. Unlike the W wires, PtMEA, as-grown VACNF MBA, and the PPy-coated VACNF MBA elicit only excitatory postsynaptic potentials (EPSPs). Furthermore, the PPy-coated VACNF MBA evokes somatic action potentials in addition to EPSPs. These results highlight the PPy-coated VACNF’s advantages in lower electrode impedance, ability to stimulate tissue through a biocompatible chloride flux, and stable vertical alignment in liquid that enables access to spatially confined regions of neuronal cells

Effects of volatile anesthetics on carotid body response to hypoxia in animals.

This study was a systematic review of the anesthetic effect on carotid body response to hypoxia. We undertook a systematic literature search (electronic plus manual) for full-paper articles in English that used methodologies enabling any anesthetic effect to be located to the carotid body. We found just 7 articles that met our inclusion criteria, incorporating 16 separate studies. Anesthetic (mean dose +/- SD 0.70 +/- 0.33 MAC) significantly depressed carotid body response by 24% (p = 0.041). There were no differences between individual agents (halothane, enflurane, isoflurane) and no influence of the use of neuromuscular blockade or of species (although the data were sufficiently sparse to interpret such sub-group analysis with caution)