The company has already developed implants that deliver a constant flow of electric signals to the brain to ease the tremors of Parkinson's disease or epilepsy. The new device aims to gather information about brain signals to determine--without the intervention of a doctor--how much stimulation is delivered and when to deliver it.

Getting to that goal requires some work in the fundamentals of brain science. The device now being tested will make some of the first long-term recordings from groups of a few thousand neurons so researchers can begin to correlate brain signals with neural diseases and therapies.

"Our hope is that we will not be just improving the lives of the patients who use this, but through that effort fundamentally understanding how the brain works as well," said Tim Denison, a senior engineering manager heading up electronics design of the device.

"You basically get a freebie--a therapy doing its job and at the same time recording scientific information," said Gregory Molnar, director of neuro-modulation research at Medtronic, Denision's counterpart on the scientific side of the work.

Startup NeuroPace Inc. (Mountain View, Calif.) is already in human trials with a roughly similar product targeted at epilepsy. The Medtronic device represents the first effort of one of the major medical electronics companies to get into the emerging field.

An update on the Medtronic effort is one of more than 1,850 presentations at the 31st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC '09), starting here on Wednesday (September 2). Medtronic hopes the device will provide new data about brain functions to both research scientists and physicians.

"Right now physicians don't get much information--you come in once every three to six months and they ask how you feel," said Denison. "There's not much data in that exchange, and it's very subjective," he said.

For life scientists, "in many respects the brain is a sort of a final frontier," said Molnar. "There's great mystery around what are brain states because they haven't been recorded" at this level of detail, he said.

Denison showed a prototype implant at Medtronic's offices in Minneapolis.