the central nervous system is the body system that controls reflex action.
the central nervous system is the body system that controls reflex action.
what body system controls reflex action?
central nervous system
one of unzer’s main contributions to science was the introduction of afferent and efferent reflexes. at its most basic level, afferent reflexes are those that move inward from something external, making its way to the central nervous system. efferent then is the opposite, where the central nervous system triggers a reflex in the muscles. unzer himself explains afferent reflexes: "to the end that an impression is felt…the external impression will have no other reflex action in the animal machines than that which is capable in virtue of its purely animal force, which it reflects upon the motor nerves…". he also goes on to explain efferent reflexes: "if, on the other hand, the external impression be also felt, then the mind, according to its psychological laws, connects volitionally with it many other conceptions, the internal impressions of which can produce through the motor nerves such sentient actions as the unfelt external impression could not have developed at all, or, at least, not in combination with the will of the animal. an example of the afferent reflex would be the traditional patellar reflex, which is also called the knee jerk reflex. an example of the efferent reflex may be the sucking reflex babies have at birth. he used reflexes to validate the point that animals without developed brains lack strong motor skills: "...we find animals without brain and without any traces of the mind, to be capable of very few kinds of movements".
johann august unzer
for a period of two years from 1840 wilhelm griesinger (1817–1868) worked as a medical assistant to zeller at the winnental asylum. while there, he adopted and adapted his senior colleague's model of a unitary psychosis. he did not, however, shares zeller's conviction regarding the nature of the human soul or character and its role in madness. a convinced somaticist and commonly considered one of the founders of materialist psychiatry, in the 1845 text which established him as one of the leading scientific psychiatrists of his era, "pathologie and therapie der psychischen krankheiten", he conceived of character, or "psychological tonus", as derived from the action of a postulated "psychic reflex action" ("psychische reflexaktion") produced by the stimulus of the accumulated representations ("vorstellungen") of the individual's life experience. the concept of psychic reflex action was drawn by analogy from the physiological reflex action of the nervous system in response to a stimulus and he argued that both forms of reflex had the same mode of action and obeyed the same physical laws. mental illnesses occurred, he posited, when the system of psychic reflex action failed to function correctly and were either diminished, leading to melancholia, or accelerated, leading to mania. his belief was that mental illness was a disease of the brain but that this in turn was caused by psychological factors. his emphasis on the brain as the central site of mental illness has led to his association with the so-called "somatiker" (somaticists) who had argued that the causes of mental illness were entirely physical whereas their opponents, the "psychiker", insisted that mental disorders were the result of psychological perversions, moral failings, or diseases of the soul ("seelenkrankheit"). as with zeller, he postulated that melancholia constituted the primary form of mental illness which then passed to mania before terminating in dementia. in his 1861 text "mental pathology and therapeutics" griesinger proposed a classificatory division of types of mental anomalies between those characterised by emotional disturbances and those characterised by disturbances in the intellectual and volitional functions. he argued, based on his observation of cases, that the former condition preceded the latter where disorders of the intellect and will appeared "only as consequences and "terminations"" of disturbances of the emotions if "the cerebral affliction has not been cured". these two categories thus constituted, for griesigner, "the different "forms" [and] the different "stages" of one morbid process". the general trajectory of this mental pathology tended towards "a constant progressive course, which may even proceed to complete destruction of the mental life". greisinger maintained his belief in unitary psychosis until the 1860s.
unitary psychosis