Tuesday, December 14, 2010

Crawling up the Cortex

Earlier last week, I had an EEG done with the neuropsychiatrist.  An EEG, electroencephalgraph, is a test of electrical waves generated by brain activity.  The brain generates four types of waves:  beta, alpha, theta,  and delta.   Beta waves are generated when you are aroused and are actively engaged.  They are low amplitude and are the fastest wave ranging from 15 to 40 cycles per secondAlpha waves  are higher amplitude and are slower ranging from 9 to 14 cycles per second.  Alpha waves occur when you aren't aroused such as when you  take a break after completing a task or when you meditate. Theta waves have greater amplitude and are even slower ranging from 5 to 8 cycles per second.  They often occur while you are daydreaming.  The last brain wave, delta, has the lowest amplitude and are the slowest ranging from 2 to 3 cycles per second.  When delta is 0, you are brain dead.

She noted that my delta waves were very slow and that the ratio between the delta and theta waves isn't quite right.  She is really concentrating on attention and asked a lot of questions about whether I feel drowsy or spacy.  I really don't feel either... sometimes, just more distracted or wandering off on a tangent.  Her feeling is that I am "overly stable" but I don't have a "flat affect" (not emotionless).

I think she is going to focus on attention and sensormotor areas of the brain... i.e. the middle of the brain.   For my long term readers, this is a bit of a shift in focus from the brain stem which governs a lot of motor functions to the middle of the brain.  Eventually, we will make it to the frontal lobe, where higher order thinking and executive function dwell.  However, the above description is overly simplistic.  Brain function is more widely spread out and more integrated.  If my gentle readers remember, as my balance and motor skills have improved, so has a certain amount of executive function (organization, memory, ability to organize thoughts, etc)  improved.  I think that the a certain amount of the reverse may hold true as well.  As attention improves so might motor skills.  My journey through the cortex may be less of a linear progression up from the brain stem through the mid cortex and to the frontal lobe but more of a corkscrew where we go round and round through different areas of the brain reiterating different different functions.  We shall see.



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