HESP120 Module 9- Language and the brain

Flow of linguistic information

• Producing a spoken word 

  • Medial temporal gyrus is activated when accessing the lexicon 

  • The arcuate fasciculus sends info from the MTG to the inferior frontal gyrus 

  • IFG interprets the received information from the arcuate fasciculus and transmits articulatory info to the motor cortex

  • The motor cortex directs the muscle movement required for speech production

• Hearing a spoken word 

  • The auditory cortex processes the information perceived by the ears 

  • MTG/ITG receives auditory info from the auditory cortex

  • MTG/ITG interprets the auditory information and matches it to a lexical entry 

  • If a word is repeated then it goes to Broca’s area then the motor cortex

• Seeing a signed word 

  • The visual cortex processes information perceived by the eyes 

  • Visual info is processed for motion/spatial analysis 

  • MTG/ITG receives this information

  • MTG/ITG interprets the auditory information and matches it to a lexical entry 

• Reading a word 

  • The visual cortex processes information perceived by the eyes 

  • The angular gyrus associates written information with a lexical entry

  • Decoding of phonological information in the MTG/ITG

  • The MTG/ITG is activated during lexical access; and makes available to meaning and pronunciation of the word

Childhood apraxia speech characteristics: inconsistent speech errors, vowel errors, difficulty producing multi-syllabic words, atypical prosody, increased errors with increased complexity/length of utterance

Autism speech characteristics: Delayed speech onset and limited vocabulary, Simplified sentence structures and grammatical errors, Flat or unusual intonation patterns, Word-finding difficulties and use of vague terms, Delayed response to verbal cues or questions, Difficulty understanding abstract language, such as idioms or humor, Poor comprehension of questions, and Struggles with context-based language (e.g., interpreting indirect requests)

• Broca’s aphasia: caused by a lesion in Broca’s area in the lower anterior portion of the motor area (nonfluent aphasia) 

  • Primary characteristics: telegraphic speech characterized by agrammatism (only content words; limited use of function words) and some difficulty with comprehension of complex syntax

• Wernicke’s aphasia: fluent aphasia 

  • Primary characteristics: significant difficulty with comprehension, frequent use of paraphasias and neologisms, and difficulty with written language