title: Neuronal loss due to prolonged controlled-current stimulation with chronically implanted microelectrodes in the cat cerebral cortex.
abstract: Activated iridium microelectrodes were implanted for 450-1282 days in the sensorimotor cortex of seven adult domestic cats and then pulsed for 240 h (8 h per day for 30 days) at 50 Hz. Continuous stimulation at 2 nC/phase and with a geometric charge density of 100 microC cm(-2) produced no detectable change in neuronal density in the tissue surrounding the microelectrode tips. However, pulsing with a continuous 100% duty cycle at 4 nC/phase and with a geometric charge density of 200 microC cm(-2) induced loss of cortical neurons over a radius of at least 150 microm from the electrode tips. The same stimulus regimen but with a duty cycle of 50% (1 s of stimulation, and then 1 s without stimulation repeated for 8 h) produced neuronal loss within a smaller radius, approximately 60 microm from the center of the electrode tips. However, there also was significant loss of neurons surrounding the unpulsed electrodes, presumably as a result of mechanical injury due to their insertion into and long-term residence in the tissue, and this was responsible for most of the neuronal loss within 150 microm of the electrodes pulsed with the 50% duty cycle.
authors.affiliation: Neural Engineering Program, Huntington Medical Research Institutes, Pasadena, CA 91105, USA. dougmc@hmri.org
authors.forename: Douglas
authors.initials: D
authors.lastname: McCreery
authors.forename: Victor
authors.initials: V
authors.lastname: Pikov
authors.forename: Philip R
authors.initials: PR
authors.lastname: Troyk
mesh_terms: D000818:Animals; D002415:Cats; D004558:Electric Stimulation / Q000009:adverse effects*; D005260:Female; D008297:Male; D008839:Microelectrodes / Q000009:adverse effects*; D009044:Motor Cortex / Q000293:injuries* / Q000473:pathology / Q000503:physiopathology*; D009474:Neurons / Q000473:pathology*; D013003:Somatosensory Cortex / Q000293:injuries* / Q000473:pathology / Q000503:physiopathology*
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