18 February 2008

Peel Scalp, Open Skull, Apply Electrodes

Medical indications for the placement of brain electrodes are multiplying. Parkinson's, paralysis, pain control, epilepsy, depression, deafness, blindness, and many more. It is good that the techniques for brain electrode implantation are growing more sophisticated.
  1. Electrodes on the scalp can only detect electrical waves that have passed through the skull, producing a weak signal susceptible to interference from mains electricity and other sources.
  2. Electrodes implanted directly into the brain produce much clearer signals, but are not well tolerated by the body. "The brain tries to get rid of [the electrodes] by covering them with a sheet of tissue," explains Schalk. "The signal degrades over time."
  3. Schalk and colleagues at Albany Medical College, Washington University in St Louis, University of Washington, Seattle, and the University of Wisconsin at Madison, all US, think a third approach will face fewer hurdles...They cover part of the brain's surface with a polymer sheet containing a grid of electrodes 2 millimetres in diameter and spaced 10 mm apart, a method called electrocorticography (ECOG). Such electrode grids are often placed in people with severe epilepsy to identify the focus of seizures within the brain.

"These grids are thin like a sheet of paper," says Schalk. "The electrodes record signals similar to those recorded by electrodes on the scalp, but with much greater fidelity."___ NewScientist
So far, the new approach looks good for long-term electrode array implantation. As the electrode arrays become more sophisticated, so do the possibilities for communication between the brain and electronic machines.
'When we turn the current on, the patients report the emptiness suddenly disappears'...By inserting electrodes into the brain while the patient is conscious (so that the surgeon knows if they have hit the right spot), Dr Mayberg found remarkable results. When she published her work, she said: "In the operating room, when we first turn the current on and get into the right location, the patients report that the heaviness or emptiness suddenly disappears. If they had a sense of a black cloud, they report it physically lifting."

The moment the electrodes were turned off, some of the positive effects vanished, but the overall results - four out of six patients were lifted from depression for six months - were encouraging.___Source

Wireheading is the science fiction concept of being able to connect the brain directly to an external electronic signal--for either "electronic bliss" or for purposes of high level communication with sophisticated computing devices (or with other wireheads).

The more sophisticated the brain electrode arrays, the more sophisticated the possible mind-machine or mind-mind interactions. "Brain chips" are already learning how to transfer neural signals across a "brain necrotic divide," as from a stroke. Such chips are slowly growing beyond mere relay stations, to learning to decode simple neural signals. As such experience grows, neurochips will learn even better neural communications skills.

In the brain, it is all about the connections, the timing, the amplitudes, and the frequencies. The smart approach to learning our way around brain signaling would be to implant smart arrays of electrodes that merely sit, watch, wait, correlate, analyse, theorise, and test theories. It goes without saying that such experiments with passive brain electrode arrays would also contribute to machine cognition research. Conversely, better machine cognition based upon brain emulation, would provide neuro-researchers with better models for testing theories and hypotheses.

Just getting started? No, just starting to get started.

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Anonymous Anonymous said...

Deep TMS and transcranial direct current stimulation are two other ways of manipulating brain functioning that may slowly get more attention in the near future. Its exciting that all this neurotechnology is coming to fruition. Check out my blog, It's about neurotechnology.


Monday, 18 February, 2008  
Blogger al fin said...

Thanks, Mike. You have some interesting articles on your blog. Brain stimulation and brain-machine interfacing are fascinating topics.

Tuesday, 19 February, 2008  

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