Caltech researchers have found that the electric fields of the brain are not just any mere by product of neuronal electrical activity but that they actually provide feedback to neurones and is an important part of the cognitive process.
In the words of lead researcher Costas Anastassiou:
... while active neurons give rise to extracellular fields, the same fields feed back to the neurons and alter their behavior.
So far, neural communication has been thought to occur at localized machines, termed synapses. Our work suggests an additional means of neural communication through the extracellular space independent of synapses.
Importantly external electric fields as weak as 1 mV/mm alter the behavior of neurones. Typically mammalian brains have fields of 2-3 mV/mm or more, what implies that they are actually affecting the brain's behavior internally.
An open question is whether electric fields external to our bodies such as those produced by all types of machines, as well as electric and telecommunication installations, do have an effect in our brains and which one. Even the Earth has its own significant electromagnetic field which interacts with the also powerful Solar one in barely researched ways.
Source: Science Daily.
Ref. paper: Costas A. Anastassiou et al., Ephaptic coupling of cortical neurons. Nature Neuroscience, 2011. Pay per view.