Évaluation des troubles lexicaux

Evaluation of Lexical Disorders

• Aphasia: A Greek term (a- privative followed by the root phasis) implying the loss of speaking ability.
• CNRTL definition: A more or less severe impairment of language function, without paralysis of articulation, where individuals experience a communicative loss due to damage to the nervous system, affecting their ability to understand and/or use linguistic signs spoken or written.

Types of Aphasia

• Broca's Aphasia (motor, non-fluent): Characterized by difficulties producing language, but with relatively preserved comprehension and conceptualization. Caused by damage to the frontal-parietal or frontal left hemisphere, specifically Broca's area. Often includes agraphia (writing difficulty) and oral reading difficulties.
• Wernicke's Aphasia (sensory, fluent): Patients have difficulty understanding words or recognizing symbolic representations (auditory, visual, tactile). This stems from a lesion in the posterior superior temporal gyrus of the dominant hemisphere (where language processing generally occurs). Commonly associated with alexia (reading difficulty).

Types of Lexical Errors

• Errors in Broca's Aphasia: Present in the linguistic production of speech.
  • Paraphasia: Mispronounced words in spoken language.
  • Paralexia: Errors in identifying/producing words during reading.
  • Paragraphia: Errors in written language production.

Lexical System

• Model: The model outlines the lexical system used in tasks such as dictation, oral naming of images, and reading aloud.
• Components:
  • Input: phonological & orthographical (entries).
  • Processing: structural description & semantic systems.
  • Output: phonological & orthographical (related to speech production)
• Comment: The model posits separate phonological and orthographic lexicons to accommodate how words are processed in reading/writing and speaking. This allows for independent retrieval of words from these separate representations. 

Errors in Image Naming

• Omissions: Failure to produce the correct name.
  • No response: Complete lack of a verbal response.
  • Circumlocution/Periphrasis: Describing the item instead of correctly naming it.
• Other errors: Incorrect word substitution (paraphasia), verbal and semantic errors, formal errors, non-verbal errors, phonemic errors, and neologisms.

Case Studies (e.g., Patient RGB and KE)

• Case details: Provided as example cases demonstrating characteristic aphasia symptoms and cognitive profiles determined by testing (e.g. auditory and written naming).
• Testing: Data often presented as percentages of various types of errors.
• Results: Findings suggest specific difficulties in language, like impaired semantic systems or phonological retrieval, impacting understanding and usage, and affecting comprehension or production in various modalities. Differences between patients show variations in the extent and location of damage.

General Comments

• Aphasia classifications, case studies, and testing methods are used to analyze the deficits in language use and understanding arising from specific brain damage.
• The underlying assumption is that there are distinct (but interacting) processes behind word retrieval/use, and comprehension. Damage to specific processes/areas will have different effects.