Biochemical basis of human sensory perception

Human sensory perception depends upon three major biochemical parameters: (1) sensory receptor function by which stem cells in the sensory epithelium are stimulated to grow and mature under the influence of specific growth factors [e.g., carbonic anhydrase VI (CA VI, a zinc glycoprotein), adenylyl cyclase, cAMP]; (2) neural transmission by which sensory messages from receptors are transmitted along cranial nerves and across CNS synapses; (3) CNS integration by which sensory information is recorded and integrated into interpretable signals through use of major excitatory (e.g., glutaminergic, dopaminergic) and inhibitory (e.g., gabaergic) neurotransmitters. Major pathology of sensory function occurs at the level of sensory receptor function and clinical data indicate that appropriate therapy can correct impaired sensory perception. For example, viral infections may inhibit taste, smell and hearing by inhibiting synthesis of one of several growth factors thereby inhibiting sensory acuity. Because saliva, nasal mucus and cochlear fluid, not blood or urine, are the major sources of these growth factors measurement of these substances in these fluids is necessary for biochemical evaluation of the pathology responsible for these inhibitions and for monitoring of treatment for correction of these inhibitions. Treatment which activates synthesis of these growth factors [by various biochemical means (increasing zinc cofactor for CA VI or inhibiting phosphodiesterase to increase cAMP synthesis)] can enhance sensory acuity and return sensory perception toward or to normal in patients who suffer with these perceptual impairments. These clinical results indicate that specific biochemical abnormalities in growth factor pathology indicate sensory receptor malfunction in human perception and treatment of these abnormalities correct these perceptual defects.