11 December 2008

Wishing You A Well - Washed World

There is the story of a woman whose world literally became brighter—looked newly washed—as soon as the electrode was activated. Other depressed patients said their sensations of “painful emptiness” disappeared. These changes abruptly vanished when patients’ electrodes were switched off. _Sciam
We are quite simply at the mercy of our brains -- its limitations, its aptitudes, its habits good and bad. We are learning more good news about the incredible plasticity of our brains. Brain plasticity can be utilised to intentionally alter some of our brain defaults, using neurofeedback, pharmacology, meditation, and other up and coming psycho-neuro-modification techniques.
In the late 1980s surgeons found that if they stimulated either the thalamus or the globus pallidus (a part of the basal ganglia) with fast pulses—up to 180 times per second—they could override the faulty connections. Scientists do not completely understand how deep-brain stimulation works, but we do know that the pulses sent to the electrode sometimes drive and sometimes inhibit the natural activity of neurons. Faster pulses, such as those used in Parkinson’s patients, tend to overwhelm and thus inhibit activity, whereas slower pulses tend to drive it by creating a tempo that the neurons strive to meet.

...Until now our best view of the living human brain has been through imaging studies such as MRI and positron-emission scans, but what we get from them is vague, along the lines of “When a person does such-and-such or thinks such-and-such, there are changes in blood flow or oxygenation in certain parts of the brain that are likely related to changes in neural activity.” With deep-brain stimulation, on the other hand, what you essentially have is an on-off switch located in a specific part of the brain. By observing what happens to the brain as a whole when that switch is activated, you can glean detailed information about how various brain structures interconnect. One particularly exciting avenue that we have pioneered is to combine deep-brain stimulation with an imaging technique called magnetoencephalography (MEG). MEG tracks neural activity on the scale of milliseconds (MRI, in contrast, gives average brain activity over a six-second period and PET over a scale of minutes), providing an exceedingly accurate, moment-to-moment report.

When we used this technique on Matthews, the phantom-limb patient, we saw that the electrode in his brain stem appeared to drive activity in many other brain regions. Among the most active when he felt pain relief was the midanterior orbitofrontal cortex. This structure, located just above the eyes, has been shown in other studies to play a pivotal role in pleasurable (or rewarding) activities such as eating, using drugs and sex. Thus, cessation of pain is an intense form of pleasure, along the lines of snorting a line of cocaine or devouring a delicious pastry. This finding confirms that the orbitofrontal cortex might be an effective new stimulation target for people suffering from anhedonia, a lack of pleasure, which is common to depression and other mental illness. _Sciam

Deep brain stimulation is an order of magnitude more dramatic than most other neuro-mod techniques. It is like an "on-off" switch, influencing whatever brain circuits it may be tapped into at the moment. By tracing the reverberating echoes of a neural stimulus down the labyrinthine interconnections of brain circuits, neuroscience will achieve greater flashes of insight into brain function, conscious sensation, and cognition.

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Blogger Bert said...

If someone were to invent deep brain stimulation that cures laziness I'd like to undergo it. (But afterwards I wouldn't visit this blog as often.)

Friday, 12 December, 2008  
Anonymous Anonymous said...

This is fascinating stuff. But I can't help feeling that it sounds a bit like me trying to fix a car with a hammer. (I'm not a mechanic.)

However, it is helping to move the field of brain science in a wonderful direction.

Martin Walker
Effective, Affordable Brain Training

Tuesday, 16 December, 2008  

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