Neuronal loss due to prolonged controlled-current stimulation with chronically implanted microelectrodes in the cat cerebral cortex

J Neural Eng. 2010 Jun;7(3):036005. doi: 10.1088/1741-2560/7/3/036005. Epub 2010 May 11.


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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cats
  • Electric Stimulation / adverse effects*
  • Female
  • Male
  • Microelectrodes / adverse effects*
  • Motor Cortex / injuries*
  • Motor Cortex / pathology
  • Motor Cortex / physiopathology*
  • Neurons / pathology*
  • Somatosensory Cortex / injuries*
  • Somatosensory Cortex / pathology
  • Somatosensory Cortex / physiopathology*