NDE researcher Titus Rivas posted a link 0n Facebook to an interesting article called "Split Brain Does Not Lead to Split Consciousness."
One of the most popular arguments against the so-called transmission theory (the idea that the brain serves as a receiver, rather than an originator, of consciousness) involves studies of patients who've undergone a callosotomy — the severing of the corpus callosum, the bundle of nerve fiber joining the left and right hemispheres of the brain. This increasingly rare operation is used as a last resort in cases of severe epilepsy. It has the effect of almost entirely isolating the two halves of the brain, which remain joined only by a few thin threads of nerve tissue (primarily the fornix and the anterior and posterior commissures) which transmit very limited electrical signals.
Previously, scientists who studied the post-op patients concluded that these people now had two distinct centers of consciousness. In effect, where there had been one mind, there were now two. This was taken by many champions of materialism as strong evidence that the mind is generated by the brain, and that mind-body (or soul-body) dualism is untenable.
The new study, however, reaches a different conclusion. Here's a summary provided by the linked article:
A new research study contradicts the established view that so-called split-brain patients have a split consciousness. Instead, the researchers behind the study, led by UvA psychologist Yair Pinto, have found strong evidence showing that despite being characterised by little to no communication between the right and left brain hemispheres, split brain does not cause two independent conscious perceivers in one brain. Their results are published in the latest edition of the journal Brain.
Pinto, lead researcher on the University of Amsterdam team, writes, "The established view of split-brain patients implies that physical connections transmitting massive amounts of information are indispensable for unified consciousness, i.e. one conscious agent in one brain. Our findings, however, reveal that although the two hemispheres are completely insulated from each other, the brain as a whole is still able to produce only one conscious agent. This directly contradicts current orthodoxy and highlights the complexity of unified consciousness."
Though the article says nothing about the philosophical implications of the study, it appears to me that one of the most commonly employed arguments against the brain as a mediator, not producer, of consciousness may now be obsolete. In fact, we can go further and say that the new study's findings are more consistent with transmission than with production. If the mind remains unified even when the brain has been divided, it would suggest that the mind is primary, the brain secondary — that consciousness originates outside the brain and is merely processed by it or funneled through it.
At the very least, the new findings greatly complicate the case for materialism.