Mechanics. Some of the variations in the internal environment are picked up by a set of nervous receptors called “interoceptors.” The psychic information that they provide is normally registered in a distorted way (deformation and translation of impulses). Now then, these tiny organs (receptors) are related to points of automatic vegetative coordination (hypothalamus, thalamus and medulla oblongata). They basically intervene in respiratory, cardiovascular and temperature adjustments, and incite the body in general to satisfy its needs through translations of “hunger” (arteriovenous difference in blood sugar), “thirst” (osmotic pressure of plasma) and “pain.” Visceral pain such as deep somatic pain initiates the reflex contraction of nearby skeletal muscles, and these contractions in turn generate pain, creating a vicious circle. On the other hand, the excitation of viscera frequently produces pain, not in itself, but in some other structure that may be located some distance away from it. This “referred” pain has numerous variants or forms of irradiation. The variations in sexual economy are also registered cenesthetically.
Nervous Pathway and Localization: The sensitive nerve fibers reach the central nervous system via sympathetic and parasympathetic pathways. The cortical reception zone encompasses almost the entire archicortex (limbic cortex) and part of the paleocortex, maintaining specialized connections with other areas. The theory of convergence tries to explain the case of “referred pain” mentioned above: There is convergence of visceral and somatic afferent fibers that act upon the same spino-thalamic neurons. Since somatic pain is more common and has “recorded” the referenced pathway, the impulses coming from visceral areas are “projected” over somatic areas. In synthesis, it will be a case of signal interpretation error.