Whereas the chakras refer to actual emanations from living organs in the human glandular system, the circuits do not. The circuits refer to a symbolic system -- as opposed to the more "real" chakra system -- that if used correctly (remembering that it's a symbolic system), can refer to attributes of consciousness and intelligence as of yet unmapped by traditional Hindu texts and doctrines. There are also attributes mapped by the Hindus that Leary et al have not touched upon yet (though, gods be willing, I may change that).

The 3rd chakra (solar plexus region) and third circuit do have relevant parallels (I like what robg says about this) but there are also important differences. They're not a clean match by a long shot. Hindu and other indigenous cultures, for example, view the solar plexus as a kind of dreaming portal through which the dreambody exits and re-enters the physical body at night during sleep. Try explaining and proving that to any rational 3rd circuit egghead.

I think what ties the 3rd chakra and third circuit together is the ego and more specifically, the state of being ego-identified. This also applies to anyone who is seriously intellect-identified and as a result, ego-inflated by excessive intellectual pride or hubris. You know, the need to be sure and the need to be right. I think these types of fixations find their focal point in the solar plexus. Check out that queezy feeling we get in our solar plexus the next time we surpass our uncertainty threshold.