Session Seven (Language and the Aphasias) Flashcards
Where is language located in the brain?
- Brain actually responds to language in a number of places, not one specific ‘centre’
- Different parts of the brain respond to different sorts of words e.g. social words, appearance words, fearful words
- However areas of the brain have been linked with language due to the effects of pathology at these locations e.g. Broca’s and Wernicke’;s
What are the two different ways the brain clusters words?
- Semantic (to do with the meaning and context of words)
- Phonemic (to do with how a word sounds)
What is Broca’s area?
Area of the brain associated with the motor element of speech, responsible for speech articulation
What is Wernicke’s area?
Area of the brain associated with the comprehension of speech.
What connects Broca’s to Wernicke’s area?
The Arcuate Faciculus
What is Geschwind’s area?
- Area of the brain located in the inferior parietal lobe, somehow related to understanding the concept behind words e.g. left and right.
- Someone with pathology in this area will understand the question and be able to articulate their response but will get muddled up between things like left and right.
- Also possibly vital for development of speech in childhood
What is the Anterior Temporal Lobe?
Area of the brain believed to be responsible for the memory component of speech
What connects Broca’s area to the ATL?
Uncinate Faciculus
What is meant by the term Peri-Sylvian anatomy?
Anatomy of the brain around the Sylvian fissure, contains areas of the brain implicated in speech. Includes Broca’s, Wernicke’s, Geschwind’s and ATL
The Arcuate Faciculus connects the speech areas of the brain, but what are it’s subdivisions?
- Long segment, connects B’s to W’s
- Anterior and Posterior segments create an indirect route that goes via Geschwind’s area.
What is the difference between a primary and a secondary aphasia?
Primary is inherent, likely caused by a developmental disorder e.g. autism
Secondary is an acquired condition e.g. from stroke
What are some common causes of secondary aphasias?
- Stroke
- Brain injury
- Drugs
- Toxins
- Space Occupying lesions
- Infections
- Neurodegenerative diseases
Define aphasia?
A disturbance to the reception and expression of language in which construction and formation of words is marked errors of form content and grammar
IMPORTANTLY: a language disorder not a speech disorder. Distinction between the two is aphasia affects both written and spoken language.
What is Broca’s Aphasia?
Expressive aphasia, capable of thinking what to say but incapable of expressing it.
What is Wernicke’s Aphasia?
Receptive aphasia, capable of expressing speech but incapable of comprehending and formulating an appropriate response.
Word salad.
Broadly speaking how do we divide the aphasias?
- Fluent vs Non-Fluent.
- Basically divides them based on whether they can form sentences or not.
- Further subdivision can be done based on whether they are able to Comprehend speech, Name objects, Repeat sentences you’ve just said to them…..
- Based supposedly on which part of the brain has been affected
When assessing someone with a suspected aphasia, what are the 4 things you need to deduce to classify which aphasia they have?
- Fluency
- Ability to comprehend a spoken sentence
- Ability to name objects
- Ability to repeat sentences spoken to them
What are some associated features of the different aphasias?
- Right hemiparesis is very commonly seen in both Global and Broca’s aphasias?
- In Wernicke’s you often see Emotional disturbance, anxiety and agitation
- In Conduction aphasia you often see hemiparesis, hemisensory deficit
What are the non-fluent aphasias?
- Global (LMA stroke, knocks out all 3 pathways involved in speech producing a total aphasia)
- Broca’s (comprehension intact but can’t articulate themselves)
What are the two parts of a stroke visible on a CT?
Core and Penumbra
What is AAA surgery for brain tumours?
Asleep-Awake-Asleep.
- Perform initial part of surgery under anaesthetic
- Wake patient up
- While they’re awake have them speak to you
- Touch their brain with a probe, testing which parts of the brain can be removed while preserving vital functions
- Put the patient back to sleep and only cut out non-essential parts.
- Especially useful if patient has a particular skill they’d like to preserve such as singing or playing an instrument.
What modalities are used for studying aphasias?
- fMRI (can be done while performing a task to aid with pre-surgery planning)
- Resting State fMRI (mapping technology not as good as pure fMRI but a lot of potential)
- Diffusion Tractography Imaging (looks at connections in the brain,
- Transcortical Magnetic Stimulation (uses magnetic stimulation applied to specific areas to try and elicit speech or motor errors, more functionally relevant than fMRI but new and untested technology)
- EEG
- Lesion studies
- Myelin mapping
What are the 3 types of pathways between areas of the brain?
- Association, within the same hemisphere
- Commissural, between the hemispheres
- Projection pathways, from the cortex down
What are the differences between the Topological and Horological approaches to explaining impairments following brain injury?
Two different approaches to working out what damage where causes what:
- Topological approach says that the area of the brain all people with e.g. Broca’s aphasia have affected is the area responsible for that function.
- Horological approach is based more on disconnection, a patient’s symptoms are dependent on the white matter damage they experience more than anything else.
- Current taxonomy of aphasias is somewhere in the middle
What part of the brain needs to get damaged to produce Wernicke’s?
W’s area (Superior Temporal Gyrus)
CLASSICAL MODEL, PERHAPS NOT TRUE
What part of the brain needs to get damaged to produce Broca’s?
B’s area (Inferior Temporal Gyrus)
CLASSICAL MODEL, PERHAPS NOT TRUE
What part of the brain needs to get damaged to produce Conduction aphasia?
- Damage to the frontal and parietal lobes
- Essentially needs to damage the arcuate fasciculus
CLASSICAL MODEL, PERHAPS NOT TRUE
What part of the brain needs to get damaged to produce Global aphasia?
Left MCA territory, knocks out every speech component
CLASSICAL MODEL, PERHAPS NOT TRUE
What part of the brain needs to get damaged to produce Transcortical motor aphasia?
Anterior to Broca’s or thalamus
CLASSICAL MODEL, PERHAPS NOT TRUE
What part of the brain needs to get damaged to produce Transcortical sensory aphasia?
Dominant posterior, temporal-occipital area, watershed strokes
CLASSICAL MODEL, PERHAPS NOT TRUE
The Wernicke-Broca’s… model of speech has been called overly simplistic, what is the evidence this is the case?
- If we compare what we think we know of the language system to systems we have a full mapping of (e.g. auditory or visual systems) its about a thousand times less complicated.
- Suggests we’re nowhere near close to understanding it.
- Furthermore, anatomically speaking Broca’s and Wernicke’s appear to have many different roles outside of language
How true is the idea that speech is lateralised into one half of the brain?
Partially true, Catani et al showed that:
- 62.5% of people show strong lateralisation
- 20% of people were bilateral but still had most of their language activity on the left side
- 17.5% of people were totally bilateral
What is the potential implication of differing levels of brain lateralisation?
It would appear to affect recovery from post-stroke aphasia:
- Forkel et al, 2014
- Looked at patients of a variety of ages who’d presented with aphasia following a stroke
- Found a correlation between how much of language activity occurred in the right part of the brain and how likely they were to recover speech function
- Better at predicting recovery than age, an 87 year old with a bilateral brain recovered when a 50 year old with a unilateral brain did not.
What are some assessment methods used in Aphasias?
F-A-S, Western Aphasia Battery, Cinderella Story
What sort of errors might you see in an aphasia assessment?
If the person has to say apple…
- Phonemic paraphasia (eliminations, substitutions and rearrangements of letters) e.g. affle, alppe
- Semantic paraphasia (substitutes that are related to target word) e.g. pear
- Semantic neologism (creates a new word because they can’t produce the target) e.g. bite-fruit
- Agrammatism (says the words but delivers the sentence in a super broken up way) e.g. yesterday me pick apple
- Paragrammatism (word salad)
- Set phrases (meaningless phrases repeated when the y can’t produce the phrase they want)
….
