Oliver Sacks, the popular author and professor of neuroscience at NYU, claims that the brain alone is sufficient to provide for the kinds of religious experience that have convinced several neuroscientists, presumably skeptical of metaphysical forces, that God and heaven do exist. The dark tunnel often described by people who have near-death experiences can be explained by the constriction of the visual field due to compromised blood pressure in the eyes. And the bright light at the end of the tunnel represents a flow of visual excitation from the brainstem to the visual cortext.
What’s the Big Idea?
Sacks does not deny that the experience of higher realms of existence can play a part in spiritual life or even have great meaning for an individual, but the roots of the experience, he insists, remain terrestrial: “The tendency to spiritual feeling and religious belief lies deep in human nature and seems to have its own neurological basis, though it may be very strong in some people and less developed in others. … [H]allucinations cannot provide evidence for the existence of any metaphysical beings or places. They provide evidence only of the brain’s power to create them.”