Neurophysiology (from Greek νεῦρον, neuron, "nerve"; φύσις, physis, "nature, origin"; and -λογία, -logia) is a part of physiology. Neurophysiology is the study of nervous system function. Primarily, it is connected with neurobiology, psychology, neurology, clinical neurophysiology, electrophysiology, biophysical neurophysiology, ethology, neuroanatomy, cognitive science and other brain sciences. This discipline is still in its infancy but the discoveries that have been made already are fascinating. I have been told that 95% of what we know about how the brain operates has been learned in the last 15 years.
Western culture has increasingly come to rely on specialized sciences to give us explanations, and the sorts of unusual phenomena that constitute central elements in religious life are widely expected to be explained by sciences already in existence and developing rapidly. Human consciousness is considered by many in the scientific and philosophic communities to be susceptible to scientific explanation, and peak religious experiences, of which Christic apparitions would be one kind, are no exception (p. 193).
A person experiencing an apparition is thought to have central nervous system activity in those areas of the brain associated with perception, belief formation, affective states, and so forth (Wiebe, p. 193).
Weston La Barre writes: We are confident that there is no "supernatural" psychic event in tribal life anywhere that may not be better understood as a dissociated state--whether endogenous dream, vision, trance, REM state, sensory deprivation, hysteric "possession"--or as an hallucinatory activity of the brain, under the influence of exogenous psychotropic substances (Anthropological Perspectives on Hallucinations and Hallucinogens cited in Wiebe, p. 194).
One of the common neurophysiological explanations for visions is that it an hallucination. The Oxford English Dictionary defines hallucination as the apparent perception (usually by sight or hearing) of an external object when no such object is actually present . While the term is really neutral it has a bad connotation. People tend to think of hallucinations as signs of mental disease or drug intoxication. The fact is, though, that perfectly normal, sober people do sometimes have hallucinations. It can be caused from a variety of factors. You can make yourself hallucinate right now. Take a look at this video.
Now it may be, as I am not a neurophysiologist, that what you just experienced is best called an illusion as opposed to an hallucination . The point is the same, however. We can perceive things as real when they are not.
Brain scientists now know that tumors and lesions of the temporal lobe can cause visual hallucinations. In addition, clinical studies have shown that electrical stimulation of this lobe can do the same thing. Maitland Baldwin describes such a procedure: As the stimulating electrode activated the depth of his left temporal lobe, he remembered these experiences with a striking sense of familiarity . . . . The senses were in color and vividly portrayed, and he described them as if he were looking at a cinematic production in color. Yet, during the description he was oriented to the reality of the environment and he recognized that the recollected scenes were somehow apart from it (Hallucinations in Neurologic Syndromes cited in Wiebe, pp. 199-200).
Other researchers have found that sensory deprivation, sleep deprivation, and hypnosis can produce hallucinations ((P. Solomon and J. Mendelson, Hallucinations in Sensory Deprivation; H. L. Williams, Illusions, Hallucinations, and Sleep Loss; and M. Orne, Hypnotically Induced Hallucinations in Hallucinations: behavior, experience, and theory, edited by Ronald K. Siegel, Louis Jolyon West).
I will continue this discussion in the next post but enough has been said here for one to realize that just because someone claims to have seen a vision of Jesus is no reason to think they actually have.
I will also interact with Christian apologists, such as Gary Habermas, who argue that the hallucination hypothesis is too problematic to offer a serious explanation of the post-mortem appearances of Jesus reported in the NT.