Very Interesting. See also Michael Gershon's The Second Brain.

In Yoga (and other Eastern physical disciplines) the gut area is often given a prominence that is lacking in Western physical cultures. I have myself felt a distinct difference in my mood/performance on those days that i practice Nauli/Uddiyana Bandha/Mula Bandha. And of course diet plays a crucial role.

I sincerely hope Modern Science unravels more and more of this connection so that we can all live healthy and better lives.