(Mostly this is for long time meditators and the generally curious.)
From LIGHTS OUT by T.S.Wiley: (A skeptic as his tone suggests)
"Michael Persinger, Ph.D., professor of neuroscience and psychology at
Laurentian University in Canada, has isolated an area of neurons in he
brain's temporal lobes that repeatedly fire bursts of electrical
activity when one thinks about God or has any feelings of spirituality.
We scientists know this from CAT scanning praying monks, nuns, and
schizophrenics as they 'talk to God'. Near the front of these temporal
lobes is the amygdala, an almond-shaped organ that imbues events with
intense emotion and a sense of meaningfulness.
"Because of the way the temporal lobes are structured and hardwired to
the amygdala, they are the most electrically sensitive regions in the
brain. Dr Persinger has personal knowledge of this because he created a
helmet with coils of wire set just above the ears (picture Woody Allen
in SLEEPER). By passing a carefully controlled electrical current
through these coils, the doctor creates a pulsating magnetic field that
mimics the firing patterns of neurons in the temporal lobes. This
creates a mystical spiritual experience, complete with a healthy dose of
peace. Dr Persinger's subjects report an 'opiate-like effect with a
substantial decrease in anxiety, a heightened sense of well-being,
similar to reports of enlightenment.'
"While Dr Persinger was doing his best mad-scientist impression,
Vilayanur Ramachandran, Ph.D., director of the Brain and Perception
Laboratory at the University of California at San Diego, was channeling
heaven. Dr Ramachandran announced in 1998 that he had discovered the
'God Module'. This 'module' is located in the brain in an area within
the temporal lobes that becomes electrically active when a person thinks
about God or spirituality or recalls a 'mystical' experence..."