Can external electric fields have similar effects on the brain? "This is an interesting question," Anastassiou says. "Indeed, physics dictates that any external field will impact the neural membrane. Importantly, though, the effect of externally imposed fields will also depend on the brain state. One could think of the brain as a distributed computernot all brain areas show the same level of activation at all times.
"Whether an externally imposed field will impact the brain also depends on which brain area is targeted. During epileptic seizures, pathological fields can be as strong as 100 millivolts per millimetersuch fields strongly entrain neural firing and give rise to super-synchronized states." And that, he adds, suggests that electric field activityeven from external fieldsin certain brain areas, during specific brain states, may have strong cognitive and behavioral effects.
Ultimately, Anastassiou, Koch, and their colleagues would like to test whether ephaptic coupling affects human cognitive processing, and under which circumstances. "I firmly believe that understanding the origin and functionality of endogenous brain fields will lead to several revelations regarding information processing at the circuit level, which, in my opinion, is the level at which percepts and concepts arise," Anastassiou says. "This, in turn, will lead us to address how biophysics gives rise to cognition in a mechanistic mannerand that, I think, is the holy grail of neuroscience."
|Contact: Deborah Williams-Hedges|
California Institute of Technology