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Wernicke
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Carl Wernicke

(1848-1905)

Biography   Theory 

Wernicke's Language Model

Wernicke's Works on Aphasia

 

Biography

Carl Wernicke was born in a small town in Upper Silesia on 15 May, 1848. He

received his secondary education at the gymnasium in Oppeln, near Breslau. With great difficulty his mother managed to enable her son to study medicine at Breslau University. After graduation Wernicke took a position as assistant in the Ophthalmology Department of Professor Foerster for six months. Then he served in the France-Prussian war of 1870 as an army surgeon. He became assistant of the “Allerheiligen Hospital” at Breslau once again, his time in the Psychiatric Department under the direction of Professor Neumann. Neumann sent Wernicke to Vienna for a period of six months to study neuro-anatomy under the supervision of Meynert. In 1866 Meynert had written an article on language disturbances in which he discussed five patients in whom autopsy revealed brain lesions at the level of the insula of Reyl. This study may have influenced Wernicke; shortly after his stay in Venna, at the age of 26, he published his first important work on aphasia, Der Aphasische Symptomencomplex (1874).

In 1875, Wernicke was appointed assistant in the Berlin Charite clinic under Westphal, where he stayed until 1878. From 1878 to 1881 he practiced medicine and, more particularly, neurology in private practice. During that period Wernicke prepared a number of publications. At the same time, he maintained a vivid interest in psychophysiology and aphasiology. Wernickes name as an expert in the field of neurology and psychiatry was definitively established by the authoritative Lehrbuch der Gehirnkrankheiten (1881 and 1883), in which a classification of the multitude of brain diseases was attempted, and the neurological method of localizing lesions was strongly furthered. In 1885, Wernicke agreed to take over the position of Neumann in the Allerheililgen Hospital and in addition he became head of the Department of Neurology and Psychiatry of the University Hospital in 1890. In the next twenty years the Breslau clinic became a center of neuropsychological investigations, where a number of eminent scientists such as Liepmann, Gldstein, Kleist, asnd Foerster developed basic concepts, such as the apraxias, the agnosias, and the asymbolias. At the turn of the century Wernicke faced a number of problems in his relationshiop with the municipal and university authorities. In 1904 the course of events finally made him accept an offer to succeed Ziehen as the head of the Klinik fur Psychiatrie und Neurologie in Halle. In 1905, Wernicke was killed in a road accident, which ended the life of one of the most outstanding neuroscientists of his time.

Theory

There are two concepts contributed to the development of Wernicke’s theory of aphasia:

The experience that Wernicke worked in Meynert’s laboratory in Vienna in the early 1870s.

In Meynert’s opinion, the cerebral cortex could be subdivided into a posterior sensory part and an anterior motor part, both parts being inter-connected by numerous fiber bundles. The fibers were supposed by Meynert to be the substrate of functional connections between different parts of the brain.

The reconsideration of the question of the relationship between dysphasic phenomena and the location of cerebral cortical lesions against the background of the knowledge obtained in Meynert’s laboratory resulted in Wernicke’s concept of the “aphasic symptom-complex’, consisting of on one extreme the pure aphemia and the motor aphasia, and on the other extreme the sensory aphasia, with a bewildering variety of dysphasic syndromes in between.

The hypothesis that stimuli affecting a particular cortical area may cause a lasting change in the organization of the local circuitry of that cortex, thus providing a memory-image?of the pertinent stimulus.

In Wernickes opinion this applied both to the primary sensory and to the primary motor cortex regions. In addition, he ventured motor activity ipso facto was always accompanied by a simultaneous sensory stimulation and, therefore, the memory-image of motor activity at the same time was to fixed both in the motor and in the sensory cortex. Association fibers between motor and sensory cortices automatically aroused the memory-images in the associated field when the cerebral cortex is stimulated at one particular site.

Wernickes language model:

(1) Brocas description of motor aphasia and Wernickes own observation of a number of patient with what the called sensory aphasia provided the cornerstones of Wernickes language model.

The model consists of a three-story edifice:

The two lowermost stories together constituted the substrate of verbal language

and speech, named by Wernicke the word-concept?faculty of the brain.

The uppermost stories possessed a different function. This level comprises the

whole of the telencephalic cortex, furnishes the drive to communicate orally, and also determines the content of the spoken word.

Wernickes theory of aphasia:

Lesions at different sites in this circuit result in a variety of dysphasic syndromes:

Aphasia typesDysphasic syndromesLesion sites
Subcortical sensory aphasia

(pure word deafness)

the patient may hear the sounds but is unable to interpret the sounds as language expressionsConnections between the primary acoustic cortex and the surrounding association cortex
Cortical sensory aphasiaAuditory comprehension impairment, fluent paraphasic aphasia with word-finding difficultyAssociation cortex
Subcortical motor aphasia

(pure word mutism)

 Connections between the primary motor cortex and Brocas motor language center?/TD>
Cortical motor aphasia Brocas motor language center
Conduction aphasia

(Wernicke postulated the existence of it)

Inability to repeat a word or sentence which had been spoken. The sensory and motor language functions are intact.Arcuate fascicle
Trancortical aphasia

~ sensory trancortical aphasia

~ motor transcortical aphasia

 Disconnection of the relationship between sensory and motor language centers on the one hand and the other cortical areas

Wernicke is neither a localizationist, nor a wholist:

There are localizable functions, but there are fiber connections of these centers with other areas of the brain cortex.

Wernicke’s view on brain functions in relation to language might be characterized most appropriately by the term “connectionism”.

Wernicke on aphasia:

1874 Der aphasische Symptomenconplex: Eine psychologische Studies auf anatomischer Basis (The Aphasia Symptom-Complex: A Psychological Study on an Anatomical Basis)

1885, 1886 Einige neuere Arbeiten ber aphasie

 

 
 

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上次修改日期: 2000年06月12日