Introduction
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IV
Neuropsychology of language
Some basic questions
So… language is located in the brain. Great!
• Is language expertise related to specific neuronal substrate?
• Is this neuronal substrate unique to language? (Domain-specificity)
• Are different language functions localized in separate brain regions? (localization)
• Do these regions work independently? (modularity)
• What evidence can help us answer these questions?
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Views on high functions in the brain
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Holism
 
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Hierarchical/
evolutionary organization
Connectionism / associationism
What evidence is needed to decide between the views?
- Lesion studies
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Localization
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Paul Broca
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• The father of Aphasia study
• Showed that Language disorders
(aphemia) are caused by lesion to
the left hemisphere
• Concluded that localization of
psychological functions is possible
1824-1880
Edwin Smith’s Papyrus
• The oldest known reference to what we now call aphasia is in
the Edwin Smith’s Papyrus (~4200 BC)
• A medical record from Ancient Egypt
• 48 cases of physical injuries, including 27 cases of head
trauma caused by fractures of the skull
• In several of these cases an association seems to be made
between head injuries and loss of speech
• One record refers to a man who is “speechless” and states
that the speechlessness is “an ailment not to be treated”
• Cardiocentric view: the soul is believed to reside in the heart
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Greek Period
• Hippocrates (400 BC)
- Hippocrates and his followers were convinced that the brain
was the organ of mind, and not the heart
- noted that language disorders coincides with hemiparesis
opposite to a brain lesion
• Plato (400 BC)
– different soul parts can be localized to different brain parts
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Greek Period
• Aristotle (350 BC)
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Aristotle believed that the heart was responsible for movement, sensation, and feeling
The only function of the brain was to cool the heat and passions of the heart…
• Herophilus (300 BC)
localized intelligence in the ventricles – became dominant view
for many years, later developed by Galen who was a doctor for
the Roman Gladiators
Galen’s ideas about medical science and the doctrine of the
cerebral ventricles as the seat of higher psychological functions
lasted more than 1200 years
Form and function of the three cerebral ventricles
(published in 1504)
The Middle Ages
• Antonio Guainerio (1481)
“I had under my care two old men, one of whom did not know more than three words […]
The other […] rarely or never recalled the right name of anyone. When he summoned
someone, he did not call him by name.”
According to Guainerio both of these speech disorders were the result of
the accumulation of too much ‘‘phlegm’’ in the posterior ventricle
• Johann Schenck von Grafenberg (1585)
“I have observed […] although the tongue was not paralyzed, the patient could
not speak because, the faculty of memory being abolished, the words were not
produced.”
Probably the first author who implicitly made a distinction between a disorder of
language (aphasia) and a disorder of speech (dysarthria), thus appreciating the
essential nature of aphasia
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17th century
• From the 17th century onward we find an increasing number
of clinical descriptions of aphasia which are generally more
extensive and precise than in the preceding centuries.
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• Many descriptions of speech loss
• Some of famous people - for example, the case of William Harvey
• When Harvey lost his power of articulation in 1657, he signed his nephews
to perform a cut in his tongue - presumably to loosen it
• Bleeding, leeching and cupping were accepted treatments
for the aphasias well into the 19th century
William Harvey
(1578 – 1657)
18th century
• Johann Gesner (1770)
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Publishes a chapter of no less than 75 pages on Die Sprachamnesie (‘‘The language amnesia’’)
Gesner’s study contains six case descriptions of aphasic patients
In this study Gesner not only gave a number of excellent descriptions of various forms and signs of
aphasia not earlier reported, but he also paid ample attention to the psychological mechanisms
underlying the symptoms of aphasia
The language amnesia: specific disorder of verbal memory consisting of an inability to associate
images or abstract ideas with their corresponding verbal symbols
Gesner’s assumption that words and their underlying concepts have specific, but separate,
representations in the brain laid the ground for associationist theories
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Self description of aphasia
In 1772, Johann Joachim Spalding , a German theologian, wrote the first accurate
description of transient speech disorder:
Introduction
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I sat down and wrote the first two words that were required; but in that
moment I was not able either to find the following words in my mind or
to carry out the necessary strokes with my pen...
... I tried to speak, to train myself, as it were, and to try and test whether
I could say something in a connected order; but much as I forced my
attention and my thoughts and proceeded with the utmost slowness I
became aware very soon of shapeless monstrous words that were
absolutely different from those I intended; my immortal soul was at
present as little master of the inner tools of language…
(Translated by Eliasberg, 1950)
Johann Joachim Spalding
(1714-1804)
Summary up to this point
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• Pre-19th century writings provided some interesting examples of speech disorders
• Different types of aphasia have been described (mainly describing symptoms)
• The relation between aphasia and brain damage was known
• Theory of aphasia existed
• The underlying neurology and bases of these disorders remained poorly understood at this time.
19th
century
• Franz-Joseph Gall (1806)
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• By early 1800’s, aphasia became a focus of intellectual speculation
• Gall developed a new theory about the function of the brain that
radically broke with the medieval ideas about the relation between
body and mind
• He made important contributions to neuroanatomy, such as the
distinction between grey matter and white matter in the brain
• According to Gall, The cortex of the brain should no longer be seen as
an indivisible whole but as consisting of multiple, distinct organs, each
with its own form and function (Localization)
• the structure of the skull reflects the size of the brain substrate
underneath (Cranioscopy, Phrenology)
Franz-Joseph Gall
(1759-1828)
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Did Gall localize language?
• Gall suggested two areas for language in the
brain area behind the eyes; for speech
articulation and for verbal memory (based on
lesions)
• Believed that all faculties existed in duplicate,
one in each hemisphere, so that each part of
the brain could serve as a complete organ of
the mind (just as each eye could serve as a
complete organ for seeing) - did not recognize
the special status of the left hemisphere in
language
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The man in the top figure has an
exceptional verbal memory and
associated protruding eyes
The man in the bottom figure has a
highly developed general faculty of
language and corresponding
swollen lower eyelids
Speech and the frontal lobes
• Jean-Baptiste Bouillaud (1825)
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• Gall’s student
• One of the most prominent supporters of Gall’s theory that the seat of
language is situated the frontal lobes
• tested the theory by reviewing the data from a large number of autopsies
of brain-damaged patients
• Linked (1825) between frontal lobe lesions and loss of speech
- Presented cases where speech disorders were correlated with frontal
lobe regions, and non-speech disorders originating in lesions outside
the frontal lobe
• Bouillaud’s claim of the existence of a ‘‘special, distinct and independent
cerebral center’’ for speech and language was severely criticized, both on
theoretical and empirical grounds
Jean-Baptiste Bouillaud
(1796–1881)
A decades-long debate
Introduction
Pierre Flourens (1842)
cerebral hemispheres were responsible for perception and intellectual functions - all
motor functions (including speech) were completely controlled by the cerebellum.
The effect of a brain lesion solely depended on its size and not on its location
Andral (1834)
found that 16 of 37 patients with a lesion of the frontal lobes did not have a speech disorder, ,
whereas a speech disorder was found in 14 patients whose anterior lobes appeared to be intact
after postmortem examination
In spite of all these criticisms, Bouillaud remained convinced that he was right.
He even offered a reward of 500 francs if a profound lesion in the anterior
lobes of the brain could be shown in a patient without a disorder of speech
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Ernst Auburtin
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• Bouillaud’s relative
• Presented (in 1861) a case of accessible frontal lobes in a living patient
due to a failed suicide attempt
• If you press the frontal lobes with a spatula, the patient stopped talking
• Paul Broca was sitting in this meeting..
Marc Dax
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• 6 weeks before Paul Broca published his account on the Localization of language in the left
hemisphere, a little-noticed article had been published.
• The manuscript of this paper was originally written by Marc Dax (1770–1837) in 1836, but it was
not published until three decades later by his son.
• Dax systematically collected more than 40 clinical cases with aphasia after a left-sided lesion
• In his paper, we find the first description of cerebral dominance in the context of language:
“[…] I believe to be able to conclude, not that all diseases of the left hemisphere must alter
the verbal memory, but that, if this memory is altered by a disease of the brain, one must
look for the cause of the disorder in the left hemisphere, and still look for it there when the
two hemispheres are diseased together.”
Dax (1865) in Hécaen & Dubois, 1969, p. 99
Paul Broca and Mr. Tan
• a French physician, surgeon, anatomist, and anthropologist
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• His most famous patient: Leborgne, a patient with speech disorder who
was nicknamed “Tan”
• Leborgne exhibited good comprehension, with almost no speech apart
from the speech automatisms tan tan and Sacré Nom de Dieu.
• It was on April 12th that M. Leborgne ("Tan") was transferred to Broca's
surgical service after being hospitalized for 21 years.
• Broca was so impressed with Aubertin's recent remarks and faith in
localization that he asked him to examine Leborgne as a test case.
• Leborgne died on April 17th, 6 days after being seen.
• Following Leborgne’s death and brain autopsy, Broca described Leborgne
at a subsequent meeting of the Anthropology Society in 1861.
Paul Broca
(1824-1880)
Broca’s area
Leborgne had a massive frontal lesion centered on the third frontal gyrus
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Characteristics of Broca’s aphasia
• Non fluent
• Telegraphic
• Open/closed class distinction
• Agrammatism: impairment of
grammatical words and inflectional
morphemes
• Usually is aware of the deficit
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Carl Wernicke
• German neurologist
• In 1874, several years after Paul Broca published his findings, Wernicke
dissected the brain of a patient whose comprehension was severely impaired
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• The lesion was discovered in the posterior, superior left temporal lobe.
• Wernicke hypothesized that this area was the locus of storage of “auditory word images”,
which were necessary for the production as well as the comprehension of speech.
Carl Wernicke
(1848 - 1905)
Wernicke’s area
Importantly, Wernicke’s aphasia has been also shown to
emerge after damage to these two specific regions:
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Characteristics of Wernicke’s aphasia
• Fluent but empty speech, normal prosody
• Grammatical inflections
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• Utterances of normal length (not telegraphic)
• Poor comprehension
• Unaware of deficit.
• The speech which is produced is phonetically well formed and
conforms to the sound-sequencing rules of English.
• Paraphasia:
– Phonological / Phonemic:
• Omissions: tying [trying]
• Additions: slipped on the lice [ice]
• Transpositions: repuceration [recuperation]
– Verbal paraphasia (Substitution of words):
• Semantic paraphasia - The substituted word is related to the
intended word. e.g. "I spent the whole day working on the
television, I mean, computer."
– Neologisms:
tarripoi, trebbin (less than half a word is said correctly)
Can you tell the difference?
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Wernicke’s Contribution
He proposed a model for aphasia, based on his and Broca’s findings.
The model is based on anatomical proximity to sensory areas
Wernicke assumed that there was a fiber tract connecting these two
language regions…
Damage to Wernicke’s also causes output problems because of the relay
Important implications in Wernicke’s Theory:
• The idea of different speech syndromes, each expressed in a different cluster of symptoms
• Dissociation between functions
• The idea of the flow of information
• The idea of representation
Carl Wernicke
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The Classic Model of aphasia
The approach which posits centers for specific processing operations along
with connections between them, came to be known as connectionism
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The connectionist approach to language was further elaborated
by Carl Lichtheim, who added a concept center (B) – not
anatomically localized
On the basis of this diagram, he postulate disorders that had not yet been
described, such as transcortical sensory aphasia, in which the projection
from Wernicke’s area (A) to the concept center (B) is disrupted.
Disconnection paradigm:
What would be the characteristics of conduction aphasia?
Intact comprehension and production, with poor repetition...
What would be the characteristics of transcortical sensory aphasia?
Impaired comprehension, intact production, repetition preserved...
Ludwig Lichtheim
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The rise and fall of localization
• Although the connectionist approach appeared to be productive, it was
criticized by later investigators who adopted a holistic view of language
functions
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• The holistic approach prevailed until connectionism was revived by the
neurologist Norman Geschwind
• In the 1960s, Geschwind crystallized early anatomical findings by
adding new insights into brain connectivity
as derived from anatomical and physiological
studies both in animals and humans
Norman Geschwind
(1926 - 1984)
Geschwind, 1970
The (new) disconnection paradigm
Geschwind also extended the disconnection paradigm beyond white
matter lesions to lesions of association cortex:
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Norman Geschwind
(1926 - 1984)
Conduction aphasia (revisited)
Interpretation of conduction aphasia had evolved:
It is no longer considered a disconnection syndrome but rather a
deficit caused by cortical dysfunction (often following damage to
the Supramarginal gyrus)
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The long segment fibres (red) connect Broca’s and
Wernicke’s territories.
The anterior segment fibres (green)
connect Broca’s and Geschwind’s territories.
The posterior segment fibres (yellow) connect Wernicke’s and
Geschwind’s territories.
Catani and ffytche, 2005