|MadSci Network: NeuroScience|
Small world. Your question traversed across the great expanse of cyberspace, just to end up all the way down here in Galveston.
As a cellular physiologist, I record electrical brain activity on a nearly daily basis. However, I use little white lab rats. Thus, I'm not really an 'expert' on chronic experimentation with humans. But if a general answer is all your looking for, I think I can help.
Electrode are occassionally chronically implanted in human patients, usually secondary to some other problem needing surgery such as epilepsy, or Parkinson's disease. For these procedures, the electrode is used for diagnostic purposes, to determine the brain area involved in the patients' condition. I think it is rare for these electrodes to be implanted longer than a week or two. Remember, the physician wants to close up the head before any infection can set in.
Some scientists use monkeys to record brain activity since they are close cousins to humans, and many brain mechanisms are similar. In these cases the electrodes can be implanted for much longer periods, up to months or even years in special cases. The risk of infection is greatest immediately following the surgical implantation of the electrode, but can always be a problem. However, application of antibiotic cream is usually sufficient to treat the infection.
Researchers have a vested interest to keep their animals healthy and happy. Poor animal health means poor (or unreliable) data.
If you have any other questions, feel free to email me.
Keep up your fantastic curiosity! That's what makes science fun!
Try the links in the MadSci Library for more information on NeuroScience.