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HoP Chapter 3 from Text

HoP Chapter 3: Textbook
greatest biological thinker of ancient Greece
Downplayed importance of the heart
The physical brain was unimpressive to him
Refused to believe what appeared to be bloodless, insensitive, and generally uninspiring mass
could be the seat of the highest human facilities – assigned this role to the heart
Saw brain as minor “condenser” of the vapors emanating from overheated humors that rose to
the top of the body (cerebrospinal fluid of the ventricles) Ancient Chinese Culture:
The spirit and soul resided in the heart
Early translated texts by Chinese Scholars, Mental philosophy = study of heart & spirit
Localized some important functions in the brain but did not believe a perfect & unified entity
like the rational soul could be housed in a divided structure like the brain
Descartes called cerebrospinal fluid “animal spirits”
Pineal gland = where Descartes believed was the most likely point of interaction between body
& mind
100 years after his death, the brain would become the center of considerable attention as
researchers attempted to understand its role in mental life.
When Descartes skull was examined and found deficient in the regions for reason & reflection,
some phrenologists retorted that the philosopher’s rationality had always been overrated.
Franz Josef Gall (1758-1828):
Controversial German physician
Among the 1st scientist to regard the entire brain as a complex organ responsible for the higher
mental functions
Reputation as a brilliant anatomist of the brain
Built on earlier works by Locke’s old teacher, Thomas Willis
Using new, delicate dissection techniques, he confirmed & developed many of Willis’s basic
findings regarding grey & white matter
Found that the 2 halves of the brain are interconnected by stalks of white matter (nerve tissue)
= commissures
Smaller tracts of white fibers cross over from each side of the brain to connect with the opposite
sides of the spinal cord
1st great comparative brain anatomist (carefully examined/compared brain
similarities/differences in animal species & differing human types
These studies showed that higher mental functions correlated with the size & health of the brain
– particularly its outer surface or cortex (we will see later that this correlation is
Gall’s anatomical findings lead to discovery that the brain & spinal cord are composed of billions
of nerve cells = neurons (each with an electronically active cell body/nucleus)
Speculated that specific parts of the brain were the seats of specific functions (large area =
function it housed should be strong)
Had no direct way of observing a living person’s brain – had to make important, questionable
“Gall’s Passionate Widow” - emotionally, erratic patient – lead Gall to believe her cerebellum
(structure at base of the brain) was unusually developed due to her well-developed neck & skull
The major weaknesses of Gall’s phrenological theory:
o 1st) Incorrectly assumed the shape of skull accurately reflects the shape of underlying
o 2nd) Gall’s choice of specific psychological qualities to localize within the brain – a
collection of 27 “faculties” located in specific brain areas called “organs”
o 3rd) unreliable methods by which its hypotheses were often tested. Gall always
maintained that his theory was based on observation, a claim literally true but
unreflective of the selectivity and arbitrariness of many of the observations.
At death, Gall’s skull was twice as thick as the average!
Thomas Willis (1621-1675):
1664 Willis published the 1st accurate & detailed description of the brain’s complex physical
shape, illustrated with plates by the celebrated architect Christopher Wren
Willis emphasized the substance of the brain’s various structures rather than its spaces & the
fluids that filled them (in speculating about how the brain functions)
Observed that brain tissue was not undifferentiated, as Aristotal thought, it consisted of 2 kinds
of substances:
o 1) a pulpy gray matter occupying the outer surface, the inner part of the spinal cord, and
several discrete centers within the brain
o 2) a fibrous white matter in the other regions; Willis speculated that the white matter
consisted of narrow canals whose function was to distribute “spirits” generated in the
gray matter.
Willis also accurately described the blood vessels of the brain - establishing firmly that the living
brain was far from a bloodless organ
 Other physicians after Willis discovered that localized interruptions to the brain’s blood supply
could cause apoplexy = stroke
 Neurons are interconnected by dendrites (receive signals from other neurons; long fibrous axons
transmit signals to other neurons) Axons cluster together to form the brain’s white matter,
while the call bodies & dendrites constitute the gray matter.
 Phrenology = science of the mind (Greek phrenos, “mind”)
 Physiognomy = the reading of a person's character in his or her physical features (big and bulgy
eyed children from Gall’s childhood – memorizers who got good grades)
 Craniometry = the measurement of the physical dimensions of the skull
 Traveling phrenologists would set up in hotels and local shops offering detailed readings (gave
guidance, marital advice/counselling, child-rearing advice)
 Most in the scientific community considered phrenology as a joke
Johann Kasper Lavater (1741-1801)
Swiss mystic & theologian
Promoted the art of physiognomy during the 1770’s - remained a popular pastime throughout
the 1800’s
Pierre Flourens (1794-1867)
Young French scientist
Conducted a series of experiments
Contrasted dramatically with Gall
Graduated from a famous medical school at 19 yo
Protégé of Georges Cuvier 9most celebrated scientist in France, “Doctor of Biology)
Appalled by the undisciplined observational strategies of the phrenologists
Studied function of the brain strictly according to experiment – he would systematically
manipulate specific variables & carefully observe the resulting effects.
He used a technique called Ablation = the surgical removal of specific small parts of an animal’s
brain - in order to observe any changes in behavior or function
Did not invent Ablation, but refined it greatly
Carefully nursed animals he experimented on back to as healthy as possible before drawing
conclusions (avoid confusion)
Believed his findings demolished phrenology
Actions initiated by the “will” in the cortex had to be out together and integrated by the
cerebellum, & the loss of coordination caused by damage to the cerebellum had to be dealt with
by the voluntary reactions in the cortex
Action propre = specific action
Action commune = common action
Saw the brain as the seat of an integrated & harmonious soul
In the 1860’s new findings suggested that Flourens’s meticulous experiments had failed to
detect some important localized functions in the cortex – and the fact that he had
overemphasized the unity of the brain’s functioning
During the height of the Flourens’s influence, one phrenological localization continued to attract
some interest and support from the vocal minority of doctors: the placement of verbal memory
in the brain region directly behind the eyes
These physicians studied loss of speech after strokes and other brain injuries
Jonathan Swift: Wrote Gulliver’s travels; following a stroke a year before dying, Swift lost ability
of speech yet seemed to understand what was communicated to him, he at times could
communicate when emotions ran high (once at a servant, and another when he was upset with
Another case: a priest suffered a stroke and lost speech except for a curse word
emotion-laden exclamations by Swift and this priest demonstrated the muscles necessary for
producing speech could still function, even though they had somehow lost the capacity for
regular speaking
Jean Baptiste Bouillaud (1796-1881)
Rejected much of phrenology – but felt there was some truth to the notion of an area that
controls language in the frontal region on the cortex
Spoke out at medical meetings and offered to pay 500 francs to anyone who could demonstrate
a case of severe frontal lobe damage unaccompanied by speech disorder (no one took him
seriously enough to accept challenge)
Ernest Aubertin (1825- 1893)
Bouillaud’s son-in-law
Found a patient whose symptoms did support Bouillaud’s theory - a soldier wounded by gunshot
on the left front of head had recovered completely except for a soft spot in his skull at the point
of the wound. When the soft spot was gently pressed – he lost his normal power of speech
(some skeptics on if the patient was being truthful or not)
Aubertin believed in that patient’s sincerity & mounted a defense of his father-in-law's theory
When presenting his views at the Paris Anthropological Society in 1861, he precipitated one of
the critical incidents in the history of brain science
Paul Broca and the Case of “Tan”
Paul Broca (1824-1880)
Chief of surgery at a major Parisian hospital
Through surgical work, he became interested in variations in people's skeletal structures,
particularly skulls
Invented several instruments for measuring skulls
1859: founded the Paris Anthropological Society to bring together other people with similar
interests (several experts joined including Aubertin)
Today’s terminology, this area of study = part of physical anthropology opposed to cultural
Aubertin found an incurably ill patient, lost speech previously, retained ability to understand
language. Aubertin announced he will perform an autopsy after his death, declared if frontal
areas were intact, he would renounce his position on the importance of that brain area to
TAN – similar patient as to Aubertin’s incurable one ended up on Broca’s surgical ward; he had
no family or support and was hospitalized; no speech; terminally ill with gangrene in leg,
remained otherwise healthy & intelligent; communicated with fingers and pointing to things, his
only vocalization was “tan” leading to the nickname “Tan”. After his death, brain autopsy by
Broca found an egg sized portion of the left hemisphere was damaged, with the center nearing
Gall’s organ of verbal memory
One confirming case did not prove a theory, of course
Broca continued, with difficulty as he could not create experimental brain lesions
(injuries/ablations) in humans as Flouren’s had with animals & cases of both speech deficits &
brain autopsies were rare!
Proved his worth as a scientist by collecting more supportive evidence
Found autopsy info from several cases that followed
Brain damage in autopsies had varied, but almost always included the same region of frontal
Surprise finding: in right-handed patients the damage always occurred on the left side (Broca’s
After debate, the speech debility from damage to that area was named aphasia (after the term
used by Plato to denote the state of being at a loss for words)
Broca became 1st established figure to successfully challenge Flourens’s conception of the
undifferentiated or unified cerebral cortex
Broca’s findings lead to new period interest in localized function of the brain - “new
phrenologists” - discovered many important localizations
Broca promoted the idea of the superior white European male brain (larger than average) - not
proven (haha)
Sensory and Motor Areas
1870: two young German physiologists, Gustav Fritsch (1837-1927) & Eduard Hitzig (1838-1907)
had idea that the brain might not be the totally insensitive organ Aristotle thought & that it may
respond to direct electrical stimulation.
Recent discoveries on the electrochemical nature of nerve signals made this idea plausible
Together these two physiologists did surgery on a dog’s cortex and applied mild electricity to
various points (this would not be approved today... Ethics!)
RESULTS from dog brain: revolutionized brain science; Fritsch & Hitzig discovered stimulation to
specific points in region no known as the motor strip elicited movements on opposite side of
Many followed their lead including...
David Ferrier (1843-1928)
Demonstrated the presence of many functionally distinct “centers” in the cortex in the 1870’s
Electrically stimulated the occipital lobe on monkey’s brain – eyes moved rapidly &
synchronously (as if looking for something)
Ablation in the occipital lobe produced blindness but no other senses affected
The occipital cortex contained visual area
Also discovered an auditory area the temporal (side) lobe
Discovered a strip behind the motor strip associated with sensory functions for the same body
parts. Ablations to this sensory strip produced a loss of sensitivity in specific parts of the body.
While ablations of the bordering motor strip caused paralysis
These findings confirmed the reality of cortical localization, they also conclusively undermined
the old phrenology
Broca’s area resembled Gall’s organ of verbal memory in some ways
Brain parts rich in white matter = association areas
frontal lobes of humans very large compared to other species, rich in white matter, speculated
to contain the large association areas responsible for humans’ superiority over other animals in
thoughtfulness & intelligence
Wernicke’s Theory of Aphasia
Carl Wernicke (1848-1905)
Young German neurologist
Used this new conception of the brain as basis of influential theory of aphasia
Noted: Broca’s area lay directly in front part of the motor strip responsible for movement of the
mouth, tongue, and face
Following this, localized damage to Broca’s area alone should theoretically afflict the memory
for spoken words but NOT the physical capacity for speaking (this could account for cases like
Jonathan Swift and Tan)
He had 10 patients with a very different sort of language disorder = sensory aphasia to contrast
motor aphasia previously investigated by Broca
These 10 patients could speak fluently with correct grammar, but their understanding of spoken
language was severely impaired, & speech was marked by many peculiar words &
mispronunciations, which Wernicke called paraphasia (occurs after brain damage)