Modern brain imaging studies show that very often they can. And, with help from new technology, they can answer us too. Neurosurgeon Michael Egnor explains:
There are ways of conversing with people in deep coma where you can, for example, look at the activation state representing Yes and the activation state representing No and you can ask them questions. You know, “Are you lonely?” “Do you wish your mother were here?” “Would you like something to eat?”, stuff like that, and they can answer you, with these brain states. In addition, some people can do mathematics in a coma. You can ask them “Is the square root of 25, 6?” and they do a No. And “Is it 5?” and they do a Yes. So there can be very high levels—not in all patients that we have found—but in many patients, forty percent, at least—of mental function in profoundly damaged brains. To the point wherre the medical profession has actually added a category to this list of ways you can be in a coma, and this is called minimally conscious state. So patients who have evidence of intellectual functioning in deep coma are called “minimally conscious,” although, frankly, they’re not really minimally conscious, they’re quite conscious.
– Mind Matters News
Pioneering research using brain imaging (fMRI) over the last fifteen years has shown that, even in deep coma, people can hear, understand, and respond. It’s no longer just anecdotes from caregivers. The controversial Terri Schiavo case might be decided very differently today.
Further reading on some of the unexpected (immaterial) ways our minds work:
If your brain were cut in half, would you still be one person? Yes, with minor disabilities. Roger Sperry’s split-brain research convinced him that the mind and free will are real .
and
Four researchers whose work sheds light on the reality of the mind The brain can be cut in half, but the intellect and will cannot, says Michael Egnor. The intellect and will are metaphysically simple.