IS IT TRUE WHAT WE PERCEIVE? REMEMBERING THE CONCEPT OF SENSORY UNIVERSE

Two weeks ago I started to experience a compression of the maxillary branch of the left trigeminal nerve. Let me tell you that my dental and maxillary troubles have become from long ago. But this time I felt something quite different; the sensation of a foreign body at intermittent periods over my left ear and the external auditory conduct of the same side. Fortunately because I`m a Medical Doctor, Ophthalmic Surgeon, Professor of Neurosciences at the Medical school and also because I have very good communication with my maxillary surgeon, I can understand the origin of this “false sensation”. This is called paresthesia in medical terms and is also very frequent in circulatory troubles and in diabetic neuropathy, for example.

If well, I can understand the origin of this strange sensation, the concept that I like to point here is that I felt it like real; currently I still can feel it sometimes, and before I get conscious of what is happening, I make a movement of my left hand trying to “remove that hair “ that is disturbing my ear. It is a real sensation of a foreign body over my left ear, but it is caused by the mechanical irritation of the V cranial pair, not because a “real object” over some part of my body. But let me tell you that I feel this sensation very real.

This particular event made me remember the concept of Sensory Universe. We introduce this concept to the “young doctors” (as happened to me many years ago) during the first days of the course. The concept of Sensory Universe is as follows: The proportion of the changes of energies that in the environment (internal or external) are occurring and that a particular species is able to register. These changes of energy (thermal, mechanical, electromagnetic, chemical) are occurring all the time at the environment, but only a small proportion of them are perceived by the individual. It will depend of the evolutionary level of this individual that belongs to a determinate species and is in direct relationship to the adaptative changes that have operated at the long of its particular phylogenetic history.

Of course we all know that the human capacity of smell is rudimentary in comparison with sharks; the capacity of hearing of the bat is by far superior to all mammals species; also the capacity of vision of an eagle is by far superior to what we, the ophthalmologist used to call “supervision” when we are talking with a patient regarding his final visual result after a refractive surgery procedure. Nevertheless the Sensory universe of the human being allow us to receive the necessary information to integrate responses, according our environmental exigencies; what we are able to perceive, is almost what we need in order to survive.

We have in almost all our sensory systems three specialized kind of neurons. First the receptor cell specialized in the registration of the environmental changes (internal or external) and in the transduction (change of energy) from the original energy to the electrical language of the neurons. Second the bipolar (or afferent) neuron, who takes the neural stimuli (now electrical) and takes it to an integrative center (e.g. thalamus). And finally a third neuron that takes it from the thalamus to the cortical cortex (neocortex) where we can register the sensation, make it conscious and generate a particular response to it.

What happened to me during these past weeks (and what is happening to many patients worldwide right now), is that a nerve mainly specialized in capture stimuli from the external media was capturing a stimuli from my internal media, from my own. It felt like a real external stimuli but it was not. Nevertheless because the entire sensory system was working properly, I felt that it was a reality. With closed eyes and without neurological knowledge I was able to make sure that “something was over my ear”. Without scientific knowledge maybe I was able to attribute this sensation to a particular extra-sensorial advice, or maybe to a disembodied spirit trying to call my attention, or maybe as a cause of fatigue or excessive stress. Without scientific knowledge I could be able to treat my self with some fashion medication with frequent television advertisement, or maybe with some psychic or hand reader or even a priest. The ability of response of our nervous system is according what we have learned and what we believe is an adequate response for survival; but unfortunately it may not be so much real.

At the end of the day my thinking and my feelings (that I`m sharing with you) went directly with my step-son; he is 21 years of age and because he has some troubles of schizophrenia, he is completely sure that a friend lives with him at his bedroom and has become his best friend; unfortunately she that passed away two years ago. The hallucinations of the schizophrenic patients are generated within the brain because of a lack of balance in neurohormones. It is sometimes very difficult to make them understand that they are experiencing something unreal, because they feel these hallucinations very real; just exactly like I felt that “hair over my left ear”.  For him, what is not real is that I am not able to believe him.

So, his friend is an existent part of the Sensory Universe of my step-son. So I have to choose, fight with him for a long life period or learn to live with “another person” in my house. How can I insist that she is not real? How can I be sure that she is not real? It is in his Sensory Universe.

Sometimes I ask to my self, how can I be sure that what I feel is a real true? So I´m sending to you the same question….

Best regards to all of you, beautiful scientist.

Arturo