Saturday, June 27, 2015

The Hyperactive Resting Brain on MEG

This brain movie shows a two minute MEG, or magnetoencephalographic profile of a subject in the resting state from the Human Connectome Project. Wavelet transforms have been used to show the changing power of activity across the cortex at three frequencies, 9, 20 and 35 Hz, in the alpha, beta and gamma bands, in real time so the changes can be seen at the actual pace they are happening.
What is striking is the high degree of activity in the resting state, showing the resting brain is highly active.

Also striking is the way the activity in higher frequencies changes more rapidly than the lower ones, suggesting brain processing uses lower frequencies for more slowly varying computations and higher frequencies for faster processes, consistent with wave phase processing similar to quantum wave-particle processes, where high energy high-frequency waves pass wavefronts over a shorter time interval even when the transmission speed of the waves are similar or identical.


Averaging over the 2-minute samples for three separate subjects at each of the three frequencies demonstrates the consistent pattern of activation involved in the resting state 'default network'. Although the processing in the movie above appears different at the alpha, beta and gamma frequencies, averaging each over the two minute sample highlights common centres of activation, consistent with the notion of the 'default network' being a centre of organization of resting state activity.

MEG provides one of the best combinations of spatial resolution and real time electrochemical changes so we can see just how the excitations spread across the resting brain when someone is relaxing and daydreaming or thinking about life issues that may be coming up, leading to the idea the resting state "default network" has a pivotal role in rehearsing situations of importance to the survival of the organism.


Here the changing excitations in the alpha at 9 Hz are shown both from the top of the brain and from each side to give as full as possible a view of the overall changes in activity.

Here the changing excitations in the beta at 20 Hz are shown both from the top of the brain and from each side to give as full as possible a view of the overall changes in activity.

Here the changing excitations in the gamma at 35 Hz are shown both from the top of the brain and from each side to give as full as possible a view of the overall changes in activity.

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