Speech and Cortical Asymmetry Flashcards
Which Brodman’s areas does Broca’s area occupy?
Areas 44 and 45
Where is Broca’s area located?
Left hemisphere just above the lateral sulcus, it is part of the inferior frontal gyrus in the premotor cortex
What is the function of the opercular cortex?
Involved in speech production
Where is the opercular cortex located?
Upper and lower ‘lips’ of the lateral fissure and is thicker in the left hemisphere
Where is Wernicke’s area located?
Specialised cortical area at the end of the superior temporal gyrus and is adjacent to primary auditory cortex (also on temporal lobe)
What is the consequence of damage to Broca’s area?
Expressive aphasia: halting speech, repetitive, disordered grammar, disordered syntax, disordered word order, meaning behind words
What is the consequence of damage to Wernicke’s area?
Receptive aphasia: fluent speech, no repetition, good syntax, grammar ok, speech is meaningless and inapproprite words are used
How may someone with damage to Broca’s area present?
Use single words and find it difficult to link words together to form grammatical sentences
How may someone with damage to Wernicke’s area present?
Speak fluently but in an almost meaningless way
What connects Broca’s and Wernicke’s areas?
A bundle of cortico-cortical association fibres known as the arcuate fasciculus.
What happens if there is damage to the arcuate fasciculus?
Conduction aphasia results
What is conduction aphasia?
When there is no function of either Broca’s or Wernicke’s areas, the individual displays an impaired ability to repeat back heard of written words but has a relatively good comprehension of language. Speech output is characterised by ‘word-finding’ difficulties, where they struggle to find the appropriate word for the situation and they have have difficulty reading aloud
When does a stroke cause speech difficulties?
When it affects the left side of the brain, as this affects Broca’s area
Describe the Wernicke-Geschwind model of information transmission between Broca’s and Wernicke’s areas
When we hear speech –> sound waves decoded in Wernicke’s area –> perceived words –> surrounding parietal and temporal cortex process the meaning of these words –> word concepts then formed in Wernicke’s –> sent to Broca’s via arcuate fasciculus –> Broca’s are converts the word concepts into grammatical sentences –> sends these to motor cortex –> speech
What is the blood supply to Broca’s and Wernicke’s areas?
Branches of middle cerebral artery
How could a stroke produce global aphasia?
If the stroke affects the proximal MCA
Which hemisphere is seen to have the most language specialisation?
Left hemisphere
What do the Broca’s and Wernicke’s corresponding regions in the right hemisphere do?
Seem to be involved in tasks requiring non-semantic speech recognition and generation such as intonation and rhythm
What is aprosodia?
Robotic, monotonous speech
What is the role of the left frontal lobe?
Deductive reasoning e.g. analysis and follow logic to a conclusion and filtering of distracting inputs
What is the role of the right frontal lobe?
Non-verbal communication skills and intuitive reasoning
What is associative agnosia?
Where an individual can’t name objects but can describe their shape, colour and size, and this is due to damage of the left inferotemporal cortex
What is aperceptive agnosia?
Difficulty recognising objects in unusual orientations or if they’re in shadow, due to damage of the right inferotemporal cortex
What occurs in order for us to be able to recognise and name an object?
Information about object –> right parietal and inferotemporal cortices (IDENTIFICATION and SEPARATION FROM BACKGROUND) –> left parietal and inferotemporal cortex (ASSIGN OBJECT A NAME)
What is the fusiform gyrus?
Part of the inferotemporal cortex
What is prosopagnosia?
Loss of the ability to recognise faces, stemming from damage to L or R fusiform gyri
What is the function of the left fusiform gyrus?
Left fusiform gyrus extracts cognitive information such as the individual’s name, from the stimulation of seeing their face
What is the function of the right fusiform gyrus?
Extracts the emotion in the face of the individual
