A brief poke around in Google Scholar produced these papers, which look useful:
Alterations in Brain and Immune Function Produced by Mindfulness Meditation. Psychosomatic Medicine 65:564 –570 (2003)
Mindfulness training modifies subsystems of attention. COGNITIVE, AFFECTIVE, & BEHAVIORAL NEUROSCIENCE Volume 7, Number 2, 109-119
Long-term meditation is associated with increased gray matter density in the brain stem. NeuroReport 2009, 20:170–17
Attention regulation and monitoring in meditation. Trends Cogn Sci. 2008 April; 12(4): 163–169.
Ahh, good point. My comment is somewhat irrelevant then with regards to this, as it seems that what you’re interested in is beyond the scope of science at present.