Summarises an article by Anil Ananthaswamy, New Scientist, 25 January 2014
This article looks at the effect of a particular type of epileptic seizure on the anterior insula region of the brain.
There are two main types of epileptic seizure; general seizures effect the whole of the cortex; this article refers to the other main type of seizure, focal or partial seizures concentrated in small regions of the brain, which is rarer than general seizure. There is also a suggestion that the stranger effects of this type of seizure have been under reported in modern times because they did not accord too well with medical belief systems.
However, the neurologist Fabienne Picard based at the University Hospital in Geneva has encouraged focal epileptic patients to discuss their experiences. They describe heightened awareness, sense of well being, absence of anything negative and harmony between the themselves and the world. Picard has related these sensations to the activity of the anterior insula cortex. The insula lies near the junction of the frontal, parietal and temporal lobes. Its conventional function is dealing with signals from within the body, and the anterior portion is involved with the subjective experience of body states. A study of one recent seizure, suggested that the seizure began in the temporal lobe before spreading to the anterior insula.
Other studies have shown that an under active insula results in a lack of sensory responsiveness. The insula is also seen as being one of the areas that predict how we are going to feel, and monitors how this prediction matches with subsequent actual experiences. Some focal epileptics have also reported an apparent slowing down of time. It is suggested that the insula checks our body states every 125 ms creating in effect a series of emotional frames, which could be disrupted by a seizure.
It is noted that the focal epileptic experience is similar to some religious experience/altered states of consciousness. Imaging suggests increased blood flow in the anterior insula after exposure to the Amazonian psychedelic, ayahuasca, which acts on the neurotransmitter, serotonin. Similarly, expert meditators have been shown to have enhanced activity in the anterior insula.