Published on March 21st, 2013 | by James Ayre
"Brain Waves" Show That Area-Specific Understanding Of Brain Function Is Too Rigid
The modern scientific understanding of how brains function has primarily been based around area-specific associations — when you talk the “speech” area of the brain is activated, etc. But now, new research on “brain waves” is shedding further light on how the brain actually works. While it has been known for quite some time that a function isn’t really tied to one location, and that the brain is essentially very plastic with different regions being able to do more or less any function, the new work adds to that, showing that the entire cortex is activated during more or less any task. And interestingly, the activity “occurs in a pattern: waves of activity roll from one side of the brain to the other.”
This matches up very well with the view of the brain as being, primarily, an integrative system. A system that takes stimuli and incorporates it into its own “actions”.
“The brain can be studied on various scales,” researcher David Alexander explains: “You have the neurons, the circuits between the neurons, the Brodmann areas – brain areas that correspond to a certain function – and the entire cortex. Traditionally, scientists looked at local activity when studying brain activity, for example, activity in the Brodmann areas. To do this, you take EEG’s (electroencephalograms) to measure the brain’s electrical activity while a subject performs a task and then you try to trace that activity back to one or more brain areas.”
The new research is exploring something of an uncharted territory: “We are examining the activity in the cerebral cortex as a whole. The brain is a non-stop, always-active system. When we perceive something, the information does not end up in a specific part of our brain. Rather, it is added to the brain’s existing activity. If we measure the electrochemical activity of the whole cortex, we find wave-like patterns. This shows that brain activity is not local but rather that activity constantly moves from one part of the brain to another. The local activity in the Brodmann areas only appears when you average over many such waves.”
Every wave of activity in the cerebral cortex is unique. “When someone repeats the same action, such as drumming their fingers, the motor centre in the brain is stimulated. But with each individual action, you still get a different wave across the cortex as a whole. Perhaps the person was more engaged in the action the first time than he was the second time, or perhaps he had something else on his mind or had a different intention for the action. The direction of the waves is also meaningful. It is already clear, for example, that activity waves related to orienting move differently in children – more prominently from back to front – than in adults. With further research, we hope to unravel what these different wave trajectories mean.”
Image Credit: © D.A.