mise à jour du
3 avril 2003
21 jan 1905
John Hughlings Jackson


Yawning is a complex, automatic, physiological phenomenon whereby the lungs are fully expanded, the heart is stimulated to greater activity, and, probably, the blood is charged more fully with oxygen.
It commences with an involontary spam of certain of the muscles of mastication and deglutition; its termination is akin to the process of sighing, and, like this manifestation of deep breathing, it reinforces respiration. At night, when respiration is slackening, or in the morning, when it has not recovered its waking rhythm, yawning is accopanied sometimes by the "streching" of successive groups of muscles the blood vessels of which have probably been compressed by the previous assomption of a constrained position. The local circulation is thus assisted and stimulated.
The preacher, the novelist and the artist employ the mechanism of yawning as an indication of ennui, of lack of interest or of waried attention, whether real or feigned.
To the clinician it should be significant of an attack of asystole and consequent temporary anaemia of the brain, especially of the corpus striatum. In deseases where "air-hunger" is a frequent symtom yawning is also exhibited. It is met with diabetes, in fatty and fibroid changes in the walls of th heart, in pericarditis and in the pathological conditions which lead to the faulty filling of the aorta. Yawning suggests the proximity of a fatal ending after copious haemorrhage and in pernicious anaemia and Addisons's disease.
Dr Hughlings Jackson recorded a remarkable demonstration shortly after the introduction of the use of the ophtalmoscope. He was surveying the fundus of an eye when suddendly the filed became pale. This pallor was due obviously to a contraction of the retinal blood vessels. He thereupon stood back, expecting something to happen, and in fact, the patient immediatly yawned. The observer had seen, in part, a spasm of the cerebral arteries.
John Hughlings Jackson 1876
"... These symptoms do not occur in, but after, the paroxysm; they are too coordinated movements to result directly from epileptic discharges; there is, I think, a duplex condition: 1) negatively, loss of control; 2) positively, increased activity of healthy lower centres. Nevertheless, the association, or sequence, is very significant.
Selected Writings of John Hughlings Jackson Edited by James Taylor On Epilepsy and Epileptiform Convulsions vol1 London, 1931
A study of convulsions. Transactions of the St. Andrew's Medical Graduates' Association, London. 1870; 3; 162-204
De l'épilepsie et autres maladies convuslives chroniques Sir William Gowers 1883

The nervous system as an evolutionary hierarchy
page 157-158
Hughling Jackson's evolutionary neurophysiology
A short history of neurology, the british contribution. Edited by F. Cliffoord Rose
Butterworth Heinmann 1999
Having extended Fritsch and Hitzig's (and Ferrier's) sensorimotor physiology to the entire cortex, Hughlings Jackson next studied the relationship between the cortex and the basal ganglia. Todd had taught that the cortex, in which the will resides, controls the striatum, which is responsible for movement. While rejecting the metaphysical function of the cortex implied by Todd, Hughlings Jackson accepted his fundamental teaching that the cortex controlled the striatum. Adapting evolutionary theory to commonplace examples of brain disease, he concluded that the cortex exerts its control of movement by a process of tonic inhibition.
In October 1874 Hughlings Jackson commenced a series of articles in the weekly Medical Press and Circular, on the topic of epilepsy, in which he appropriated Herbert Spencer's evolutionary theory to neurological disease (Smith, 1982). In this series he wrote that the highest nervous centres evolved out of the lower. He considered the nervous system as a hierarchy 0f three centres, of which he wrote, "... the very highest of all nervous centres are but complex rearrangements of lower centres, and these of still lower centres unto the lowest, which last directly represent impression and movements" (Hughlings Jackson, 1874-1876, ed. Taylor, 1958, p. 162-273). Spencerian evolutionary theory dictates that higher centres are more complex, more specialized and more numerous than lower centres, and that the climax of development of nervous centres occurs in the human. Under normal conditions, the cortex, as the higher evolutionary centre, controls and inhibits the function of the striatum, the lower centre. The nervous system as an evolutionary hierarchy Hughlings Jackson expressed the pathophysiology of the nervous system as the reverse of evolution, or dissolution. Therefore, patients with dissolution of the nervous system should exhibit symptoms which are less complex, less specialized and less voluntary than normal subjects. Patients with diseases of the highest centres develop two types of symptoms: negative symptoms due to the loss of higher centres and positive symptoms due to the emergence of lower centres. Positive symptoms are simpler and less differentiated than the negative symptoms which they replace (Harrington, 1987). To support this contention Hughlings Jackson cited Francis Edmund Anstie's 1865 work on stimulants and narcotics, in which Anstie claims that the excitement sometimes seen in narcotized people was the result of the removal of controlling influences rather than direct stimulation of the brain (Anstie, 1865, p. 86).
In 1875, Hughlings Jackson used postictal mental disorders to illustrate the relationship of the cortex to the basal ganglia (Hughlings Jackson, 1875). If the sudden discharge of nervous energy produces an epileptic seizure, then seizures which begin with discharge of higher centres begin with loss of consciousness, but those which begin with discharge of lower centres spare consciousness. According to Hughlings Jackson, postictal mental symptoms, like postictal physical ones, have the two components predicted by evolutionary theory: the negative symptom of postictal confusion, from the temporary paralysis of higher centres, and the positive symptoms of postictal mania or agitation, from the emergence of the function of the previously inhibited lower centres.
Over the succeeding years Hughlings Jackson elaborated these themes. In 1881 he explicitly divided the nervous system into a three-level evolutionary hierarchy (Hughlings Jackson, 1881, ed. Taylor, 1958). The next year he identified the specific anatomical structures corresponding to each motor level. The lowest level, representing parts of the body most directly, consists of the anterior spinal horns and homologous cranial motor nerve nuclei. The middle level, which re-represented the body, is composed of the motor cortex and the basal ganglia. The highest level, which re-re-represents the body, consists of the premotor frontal cortex (Hughlings Jackson, 1882, ed. Taylor, 1958; York and Steinberg, 1994).