Embed Size (px)
Citation preview
The faculty of articulate speech
The Bicêtre Hospital is located in Le Kremlin-Bicêtre, which is a commune in the southern suburbs of Paris, France. It lies 4.5 km (2.8 miles) from the center of Paris. The Bicêtre Hospital was originally planned as a military hospital, with construction begun in 1634. With the help of Vincent de Paul, it was finally opened as an orphanage in 1642. It was incorporated into the Hôpital Général in 1656. In 1823, it was called the Hospice de la Vieillesse Hommes. In 1885, it was renamed the Hospice de Bicêtre. In its history it has been used successively and simultaneously as an orphanage, a prison, a lunatic asylum, and a hospital. Its most notorious guest was the Marquis de Sade.
The Bicêtre is most famous as the Asylum de Bicêtre where Superintendent Philippe Pinel is credited as being the first to introduce humane methods into the treatment of the mentally ill, in 1793.
The Bicêtre is referenced in The Birth of the Asylum from Foucault's Madness and Civilization. In it, Pinel's methods are classified as more devious than humane.
We know that the phrenological school placed at the front part of the brain, in one of the convolutions that lie on the orbital arch, the seat of the faculty of language. This opinion, which had been accepted, like so many others, without sufficient evidence, and which besides rested only on a very imperfect analysis of language phenomena, would have without doubt disappeared with the rest of the system, if Mr. Bouillaud had not saved it from foundering by making some important modifications to it, and by surrounding it with a parade of evidence borrowed above all from pathology.
Without considering language as a simple faculty dependent on a single cerebral organ, and without looking to hem into an area of a few millimeters the location of this organ, as had been done by Gall's school, this professor was led by the analysis of a great number of clinical facts, followed by autopsies, to concede that certain lesions of the hemispheres abolish speech without destroying intelligence, and that the lesions always have their seat in the frontal lobes of the brain.
There is a general faculty of language that presides over all modes of the expression of thought, and it may be defined: the faculty of establishing a constant relation between an idea and a sign, whether this sign be a sound, a gesture, a figure, or any other trace.
There is a general faculty of language that presides over all modes of the expression of thought, and it may be defined: the faculty of establishing a constant relation between an idea and a sign, whether this sign be a sound, a gesture, a figure, or any other trace.
Moreover, each species of language necessitates the play of certain organs of emission and reception. The organs of reception are sometimes the ear, sometimes sight, sometimes even touch. As for the organs of emission, they are put in play by the voluntary muscles, like those of the larynx, or the tongue, of the soft palate, of the face, the upper limbs, etc.
All regular language supposes therefore the integrity, (1) of a certain number of muscles, of the motor nerves that serve them, and the part of the central nervous system from which these nerves arise; (2) of a certain external sensory apparatus, of the sensory nerve that departs from these, and of the part of the central nervous system to which this nerve connects; (3) finally, the part of the brain that holds under its dependence the general faculty of language, such as we have come to define it.
There are cases where the general language faculty persists unaltered, where the auditory apparatus is intact, where all the muscles, not even excepting those of the voice and those of articulation, obey the will, and yet where a cerebral lesion abolishes articulated language.
This abolition of speech, in individuals who are neither paralyzed nor idiots, constitutes a symptom so singular that it seems to me useful to designate it with a special name. I will give it, therefore, the name of ________; it is only the faculty of articulating words that these patients lack.
There are cases where the general language faculty persists unaltered, where the auditory apparatus is intact, where all the muscles, not even excepting those of the voice and those of articulation, obey the will, and yet where a cerebral lesion abolishes articulated language.
This abolition of speech, in individuals who are neither paralyzed nor idiots, constitutes a symptom so singular that it seems to me useful to designate it with a special name. I will give it, therefore, the name of aphemia; it is only the faculty of articulating words that these patients lack.
Aphasia -- an acquired disorder oflanguage.
They hear and comprehend all that one says to them; they all have their intelligence; they emit vocal sounds with ease; they execute with their tongue and their lips movements much more extensive and energetic than those required for the articulation of sounds, and yet the perfectly sensible response that they would want to make is reduced to a very small number of articulated sounds, always the same and always performed in the same manner; their vocabulary, if we can call it that, is composed of a short series of syllables, sometimes of a monosyllable that expresses everything, or rather that expresses nothing, for this unique word is most often a stranger to all vocabularies.
“TAN”
The nature of this faculty and the place that it must be assigned in the cerebral hierarchy can give rise to some hesitation. Is it only a species of memory, and the individuals who have lost it have lost only, not the memory of words, but memory for the procedure that must be followed to articulate words?
Have they come to this by a condition comparable to that of a young child who already understands the language of those around him, who is sensitive to blame and praise, who points out with his fingers all the objects that he can name, who has acquired a crowd of simple ideas, and who, to express these, can do no more than stammer out a single syllable?
This hypothesis seems to me quite likely. It might be possible, however, that it is otherwise, and that aphemia is the result of a locomotor ataxia limited to the part of the central nervous apparatus that presides over movements governing the articulation of sounds.
One objects, it is true, that these ill people can freely execute with their tongue and their lips all the movements other than those of articulation; that they can immediately move, when asked, the point of their tongue upwards, downwards, to the right, to the left, etc.; but these movements, precise as they may seem to us, are infinitely less so than the excessively delicate movements that are required for speech.
In locomotor ataxia of the limbs, one observes that the patients voluntarily execute all the large movements: if one tells them to lift their hand, to open it, to close it, they do it almost always without hesitation; but when they want to execute more precise movements, to seize, for example, in a certain manner, an object of small volume, they go beyond or stay behind the goal; they do not know how to coordinate the contraction of their muscles in a manner to obtain a result of determined value, and they make mistakes much less in the direction of their movements than in the quantity of force that they have to deploy and in the order of succession of partial movements of which the grasping of objects is composed.
One can therefore ask if aphemia is not one species of locomotor ataxia limited to the muscles for the articulation of sound, and, if it were so, the faculty that the ill people have lost would not be an intellectual faculty, that is to say a faculty belonging to the thinking part of the brain, it would be only a particular case of the general faculty of coordination of muscular action, a faculty that depends on the motor parts of the nerve centers.
One can therefore make at least two hypotheses about the nature of the special faculty of articulated language.
In the first hypothesis, there would be a superior faculty, and aphemia would be an intellectual trouble; in the second hypothesis, it would be a faculty of a much less elevated order, and aphemia would be no more than a trouble of locomotion.
Though the latter interpretation appears to me much less probable than the other, I would not yet dare to commit myself in a categorical manner if I were reduced to only the lights of clinical observation.
Tan’s brain
Broca's area
Broca’s area is located in the left inferior frontal cortex, above and behind the left eye.
What is the function of Broca's region?
Is there a faculty of articulate speech?
For this study, the researchers set out to pinpoint the functions of distinct sections of Broca’s area by scanning subjects with functional magnetic resonance imaging (fMRI) as they performed a variety of cognitive tasks.
To locate language-selective areas, the researchers asked subjects to read either meaningful sentences or attend to sequences of nonwords. A subset of Broca’s area lit up much more when the subjects processed meaningful sentences than when they simply attended to nonwords.
Language-selective and domain-general regions lie side by side
withinBroca's areaE. Fedorenko, J. Duncan & N.
KanwisherCurrent Biology,
2012
The researchers then measured brain activity as the subjects performed easy and difficult versions of general cognitive tasks, such as doing a math problem or holding a set of locations in memory. Parts of Broca’s area lit up during the more demanding versions of those tasks. Critically, however, these regions were spatially distinct from the regions involved in the language task.
These data allowed the researchers to map, for each subject, two distinct regions of Broca’s area — one selectively involved in language, the other involved in responding to many demanding cognitive tasks. The general region surrounds the language region, but the exact shapes and locations of the borders between the two vary from person to person.
The general-function region of Broca’s area appears to be part of a larger network sometimes called the multiple demand network, which is active when the brain is tackling a challenging task that requires a great deal of focus. This network is distributed across frontal and parietal lobes in both hemispheres of the brain, and all of its components appear to communicate with one another.
The language-selective section of Broca’s area also appears to be part of a larger network devoted to language processing, spread throughout the brain’s left hemisphere.
We found two distinct subregions, each present in at least 90% of subjects individually, with strikingly different but highly reliable functional profiles, lying side by side within Broca’s area and each spanning the BA44/45 boundary (Figure 1). One subregion, identified in each subject as responding more during the processing of sentences than nonwords, showed little response to any other task, with the BA45 portion being particularly selective. ......This region is part of a broad left-hemisphere language-selective network, with additional major components in left temporal and parietal lobes. In contrast, another set of subregions exhibited extreme domain generality, with a greater response to the harder than the easier condition in each of the seven tasks, regardless of stimulus (verbal/ nonverbal) and task (arithmetic/working memory/inhibition). Our data thus provide seven statistically independent replications of this same hard > easy contrast across diverse cognitive domains.
The study demonstrates that a small piece of the brain can compute three different things at different times – within a quarter of a second – and shows that Broca's area doesn't just do one thing when processing language. The discoveries came through the researchers' use of a rare procedure in which electrodes were placed in the brains of patients. The technique allowed surgeons to know which small region of the brain to remove to alleviate their seizures, while sparing the healthy regions necessary for language. Recordings for research purposes were then made while the patients were awake and responsive. The procedure, called Intra-Cranial Electrophysiology (ICE), allowed the researchers to resolve brain activity related to language with spatial accuracy down to the millimetre and temporal accuracy down to the millisecond.
Sequential Processing of Lexical, Grammatical, and Phonological
Information Within Broca's Area
Ned T. Sahin et al.Science 2009
For this study, the researchers recorded activity inside patients' brains while they repeated words verbatim or produced them in grammatical forms such as past tense or plural – a task that humans effortlessly compute every time they utter a sentence.
Example
Task 1: Repeat “GO” -- Response is “GO”Task 2: Past tense of “GO” -- Response is “WENT”.Task 3: Plural of “MAN” -- Response is “MEN”.
"We showed that distinct linguistic processes are computed within small regions of Broca's area, separated in time and partially overlapping in space". Specifically, the researchers found patterns of neuronal activity indicating lexical, grammatical and articulatory computations at roughly 200, 320 and 450 milliseconds after the target word was presented. These patterns were identical across nouns and verbs and consistent across patients.
"The first evidence that parts of the brain may correspond to parts of the the mind was the discovery that patients with damage to Broca's area were unable to talk but could still think. In the 150 years since this discovery, progress in understanding what precisely Broca's area contributes to language has been disappointing," said principal investigator Eric Halgren, PhD, professor in the UCSD Department of Radiology. "These results suggest that Broca's area actually consists of several overlapping parts, performing distinct computational steps in a tightly timed choreography, a dance that may simply have been undetectable due to the level of resolution of previous methods."
What cognitive functions does Broca's region
carry out?
Answer: Both a domain-specific function (language) and a domain-general function(handling demanding situations).
The anatomical areas for these two functions are different.
Note that the domain specific function is localized in the left hemisphere .
The domain-general function is localized in Broca's region of both hemispheres.
Is there a faculty of articulate speech?Word form
Grammar
Articulate
Word Form (e.g. eat)
Grammar (e.g. ate)
Articulate (e.g. ‘ayt’)
Timing (temporal dynamics) reveals
the presence of thefaculty of articulate speech.
THE WERNICKE LICHTHEIM DIAGRAM
THE WERNICKE LICHTHEIM DIAGRAM
M
Wernicke conceived of a two-layer system which he diagrammed in the form of a house. The ‘ground-floor’ is the speech pathway from auditory input to spoken output that we have already discussed. The ‘roof’ of the house represents the meaning of the word. Wernicke used the term ‘Ideation’ to refer to what we now refer to as the semantic or conceptual content of a word.
Such a diagram -- though rudimentary -- of the connections between word form (in this instance, centers A and M) and meaning (Ideation) was produced by Ludwig Lichtheim and is known as Lichtheim’s house. In general, we refer to such a diagram as a functional architecture, because it depicts in abstract form the processes and connections involved in carrying out a particular set of cognitive operations. Since Lichtheim’s schema included many core ideas developed by Wernicke, the model was ultimately referred to as the Wernicke-Lichtheim diagram.
MThe stored auditory form of words
The stored articulatory
form of words
The meaning of words
HAND
HAND“HAND
”
This type of diagram is known as a functionalarchitecture.
M
The meaning of words
M
The meaning of words
M
M
HAND
HAND“HAND
”
M
HAND
HAND“HAND
”
Via meaning
The ‘direct’ route
M
Task 1: Repeating a word spoken by the examiner.Task 2: Repeating a nonsense word spoken by the examiner.Task 3: Naming a picture.Task4: Matching a spoken (i.e auditory) word to a picture amongst four semantically related alternatives.
“Tiger”
M
The meaning of words
Task 1: Repeating a word spoken by the examiner.Task 2: Repeating a nonsense word spoken by the examiner.Task 3: Naming a picture.Task4: Matching a spoken (i.e. auditory) word to a picture amongst four semantically related alternatives.
Pure word
deafness
VisionVision
M
The meaning of words
Task 1: Repeating a word spoken by the examiner.Task 2: Repeating a nonsense word spoken by the examiner.Task 3: Naming a picture.Task4: Matching a spoken (i.e. auditory) word to a picture amongst four semantically related alternatives.
Pure word
deafness
VisionVision Impaired on Tasks 1, 2 and 4. Intact on Task 3
M
The meaning of words
Task 1: Repeating a word spoken by the examiner.Task 2: Repeating a nonsense word spoken by the examiner.Task 3: Naming a picture.Task4: Matching a spoken (i.e. auditory) word to a picture amongst four semantically related alternatives.
The capacity for speech production is maintained but with certain limitations. Observations of daily speechusage and the process of speech development indicate the presence of an unconscious, repeated activation andsimultaneous mental reverberation (i.e. echo) of the auditory form of the word, which exercises continuous monitoring of the motor word form. Apart from impairment in comprehension, the patientalso presents aphasic symptoms in speech producedby absence of the unconscious monitoring of the spokensound.
M
The meaning of words
Task 1: Repeating a word spoken by the examiner.Task 2: Repeating a nonsense word spoken by the examiner.Task 3: Naming a picture.Task4: Matching a spoken (i.e. auditory) word to a picture amongst four semantically related alternatives.
M
Task 1: Repeating a word spoken by the examiner.Task 2: Repeating a nonsense word spoken by the examiner.Task 3: Naming a picture.Task4: Matching a spoken word to a picture amongst four semantically related alternatives.
YIFE
“You”“Year”“Young
”
“Wife”“Life”“Knife”
VisionVision
M
Task 1: Repeating a word spoken by the examiner.Task 2: Repeating a nonsense word spoken by the examiner.Task 3: Naming a picture.Task4: Matching a spoken word to a picture amongst four semantically related alternatives.
VisionVision
M
Task 1: Repeating a word spoken by the examiner.Task 2: Repeating a nonsense word spoken by the examiner.Task 3: Naming a picture.Task4: Matching a spoken word to a picture amongst four semantically related alternatives.
VisionVision
M
Task 1: Repeating a word spoken by the examiner.Task 2: Repeating a nonsense word spoken by the examiner.Task 3: Naming a picture.Task4: Matching a spoken word to a picture amongst four semantically related alternatives.
VisionVision
M
Task 1: Repeating a word spoken by the examiner.Task 2: Repeating a nonsense word spoken by the examiner.Task 3: Naming a picture.Task4: Matching a spoken word to a picture amongst four semantically related alternatives.
VisionVisionConduction
aphasia
