- 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).
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