The magnitude of the number of neurons that comprise the brain suggests that the reflexologist's approach to studying behavior and the nervous system is too simplistic on several grounds. Following is an examination of the problems associated with applying this line in light of my own research on a reflex mechanism in humans.

The model of this reflex is that an intense environmental stimulus activates sensory neurons which send excitatory inputs to a response "organizing center" which in turn signals the motor neurons to produce the response, an overt bodily reaction the initial component of which is an eye blink. This model takes into account the capacity for this reflex response to be modified by the presentation of other stimuli. The modification effect examined in my research was prepulse inhibition (PPI) whereby a prestimulus presented prior to the reflex-eliciting stimulus results in a reduction in response magnitude to the reflex-eliciting stimulus. The explanation put forth by psychologists conducting research on these effects is that the prestimulus signals two separate pathways -- an excitatory one and an inhibitory one. The decrease in response magnitude when a stimulus precedes a reflex-eliciting stimulus has been explained as being due to the inhibitory pathway's being slower than the excitatory one.

The premise of reflexology, that specific motor responses can be elicited by the presentation of discrete stimuli, underestimates both the complexity of behavior and of the events in the environment and overestimates their predictability. While actions commonly termed reflexes occur often, the direct modification effects were not obtained on every trial or for every participant.

Not only are behaviors not as simple as the blink of an eye, there is also the issue that events in our external environments are not as simple as specific, discrete stimuli. Human behavior is coordinated into a continuous network (that is constantly changing and being recreated) of past experiences and present circumstances and therefore cannot be isolated as a time line of segregated events and corresponding behaviors. Similarly, even specific events in the environment such as a car crash are intertwined into a network of external events which mirrors the complexity and magnitude of out internal physiological structures. Human behavior cannot be extracted as a specific event from a lifetime of events; likewise, the brain cannot be extracted as a lump of functioning neurons at the time of an event as it changes with and reflects our past experiences. Therefore behavior, experiences, events in the environment should be considered in the continuum of a human life. For example, how would reflexology account for the following scenario: Mary is a twenty-five year-old college student who bounds out of bed at 4:00 every morning to study feverishly. She is putting her life back together again after having abused hard core drugs for the past five years. Her inability to focus her attention due to the extreme anxiety over "messing up again" compounds her problem of finding that she no longer grasps concepts as quickly as she did before her years of drug abuse, so she studies nonstop.

The basic assumption of reflexology is that the relationship between the reflex-eliciting stimulus and the observable bodily reaction serve as an indication of what went on in the nervous system in between the specific stimulus and the specific response. However, the dangers of drawing such conclusions is evident in the explanation of PPI of the reflex response which I examined. An additional note of concern with the reflex approach to examining the nervous system is that this model ignores the interrelatedness of the nervous and endocrine systems and the ability of a person's mental activities to alter the body via these systems. The question boils down to whether or not the reflex observations warrant these broad-based conclusions. The magnitude of the number of neurons in then nervous system indicates that the reflex arc is inadequate to describe the complex interaction of 10E12+ neurons.

A rich and interesting set of observations and issues. "Reflexology", of course, didn't start as "reflexology" but rather as the then best (perhaps only) way to make meaningful observations on the brain/behavior intersection. In a very real sense, anything one does today is standing on the shoulders of "reflexology". In the making mistakes is right spirit, the critical need is to try and isolate and characterize the particular problems of a given model so that one can on to the next one. You've put your finger on several different ones that should be kept in mind, including one that clearly not enough thought has yet been given to: the temporal embedness of behavior. PG