week 8 long Language Processing and Disorders of Language

PSY325 - Neuropsychology and Clinical Neuroscience

Language Processing and Disorders of Language

Lecture Outline

  • Introduction
      - Key linguistic and neuropsychological terms
      - Basic Neuroanatomy of Language

  • Verbal Language Processing
      - Language disorders and early neural models
      - Cognitive Neuroscience of Language
      - Modern Neural Models

  • Visual Language Processing
      - Reading disorders
      - Writing disorders
      - Neural models

Psycholinguistic Elements of Language

  • Grapheme: Smallest unit of written language.

  • Phoneme: Smallest unit of sound.

  • Morpheme: Smallest unit of meaning.

  • Syntax: Rules of putting words together to create meaning (grammar).

  • Semantics: Word meaning (concept).

  • Extralinguistic information: Information beyond word meaning that is essential for interpretation.

  • Prosody: Vocal intonation (stress, pitch, rhythm).

  • Lexicon: Word storage in memory.

The Mental Lexicon

  • Definition: The mental store of word information.
      - Word forms: Comprises visual (orthographic) & sound (phonological) representations.
      - Syntactic: How words combine to form sentences.
      - Semantic: Relates to word meaning.
      - Reference: Levelt (1994).

  • Semantic Network: Collins & Loftus (1975).

  • Evidence: Derived from word frequency, neighborhood, and semantic priming effects.

Language Comprehension

  • Spoken and Written Language Comprehension: These share some processes but also differ.

Language Disorders: Key Terms

  • Dysarthria: Muscle control issues affecting speech.

  • (Speech) Apraxia: Difficulty in planning speech movements.

  • Aphasia: Language impairment due to brain damage.

  • Paraphasia: Involuntary substitution of words.

  • Anomia: The inability to name objects.

  • Alexia: Acquired reading disability.

  • Agraphia: Acquired writing disability, can affect both spoken and written language.

LH Lateralization of Language

  • Neural Assessments:
      - Brain damage assessments.
      - Split brain procedure evaluations.
      - Electrical stimulation studies.
      - Wada Test: Uses sodium amytal to assess cerebral hemisphere functions.
      - Imaging research findings.

Neuroanatomy of Language

  • Broca's Area: Located in the inferior frontal cortex.

  • Wernicke's Area: Located in the superior temporal gyrus.

  • Key Structures:
      - Supramarginal gyrus.
      - Inferior parietal lobule.
      - Angular gyrus.
      - Sylvian fissure.

2.1 History of Aphasia and Early Connectionist Models

  • Broca’s Aphasia: Characterized by impaired speech production.

  • Wernicke's Aphasia: Characterized by impaired speech comprehension.

  • Connectionist Models: Early models linking specific brain regions to aphasia forms.

Broca's (Expressive) Aphasia

  • Characteristics:
      - Spontaneous Speech: Difficulty leading to disjointed phrases.
        - Example: "Son … university… smart… boy… good …… good…"
      - Repetition: Difficulty repeating phrases.
        - Example: Repetition of