Lecture 7: Production And Comprehension Disorders Flashcards
Anatomy of stroke
- middle cerebral artery is the most common affected blood vessel in the brain, running along the Sylvian fissure.
- blockage in posterior cerebral artery and anterior cerebral artery also result in stroke and aphasia
Types of stroke
- ischemic stroke
- haemorrhagic stroke
- transient ischemic attack
Ischemic stroke
Blocked artery (85% of strokes)
haemorrhagic stroke
Ruptured artery
Transient ischemic attack
Not long-lasting interruption of blood supply
Language recovery post-stroke. When is the plateau of language function after stroke?
6-9 months
3 main approaches to studying aphasia and language
- Cognitive neuropsychological approach
- Syndromes approach
- Lesion-deficit correlation approach
Cognitive neuropsychological approach
Comprehensive case studies of individual patients focused on functional architecture of language rather than neuroanatomy
Syndromic approach
Investigation of groups of individuals sharing a clinical syndrome of feature
Lesion-deficit correlation approach
Imaging of damaged brain regions and association to language deficits
What underlies the quick recovery immediately after stroke?
- reperfusion of key language regions post-stroke
- inflammation decreased
What underlies the quick recovery in the first few weeks and 3-6 months after stroke?
- Degeneracy
- Variable neuro-displacement
Anatomical division of LIFG (Left Inferior Frontal Gyrus)
- Pars triangularis
- Pars opercularis
- Pars orbitalis
Pars triangularis
Verbal working memory, semantic and thematic coherence
Pars opercularis
Coordination of the speech organs, phonological processing
Pars orbitalis
Semantic processing, phonological processing and syntax
Dysarhria
- loss of control over articulatory muscles
- classified as motor speech disorder
- difficulties to produce clear speech and to regulate loudness, pitch and rhythm
Apraxia of speech
- deficits in the ability of program articulation
- classified as speech sound disorder
Dronkers, 1996: lesion-deficit correlation approach to Broca’s aphasia conclusions
- double dissociation across patient groups
- damage to left anterior insula
- anterior insula likely involved in articulatory planning and essential for coordinating speech articulation
Wernicke’s aphasia
- receptive aphasia
- paragrammatic
Conduction aphasia
Malfunction in repetition
Geschwind’s model of language processing: visual input
Visual input -> visual areas -> angular gyrus -> Wernicke’s area where meaningful sequence is generated -> transmission to Broca’s area via arcuate fasciculus -> translation to motor commands conveyed to speech muscles for articulation
Geschwind’s model of language processing: auditory input
Auditory input -> parietal-temporal-occipital association cortex (angular gyrus) -> Wernicke’s area for phonological representation-> transmission to Broca’s area via arcuate fasciculus -> word representations activate related concept and auditory comprehension is realized -> translation to motor commands conveyed to speech muscles for articulation
Atomic aphasia
- written and spoken production
- difficulties with retrieving known words
- early sign of primary progressive aphasia
Lesion of anomic aphasia
LH in left angular gyrus
Two levels of word retrieval difficulties of anomic aphasia
- semantic level: patients show category-specific problems
- speech-output level: errors are dependent on usage of frequency of words
Global aphasia
- production and comprehension
- impairment of receptive and expressive
- most severe subtype
Lesion of global aphasia
Stroke in middle cerebral artery
Pure word deafness
- auditory comprehension
- behavioral disorder with severe spoken language comprehension deficit (also named auditory agnosia)
Lesion of pure word deafness
Bilateral lesions in the superior temporal gyrus
disconnection theory about pure word deafness
- Lesion disconnects LH Wernicke’s area from auditory cortex
- Sounds can be heard but not analyzed
Pure alexia
- visual comprehension
- inability to read or comprehend written language
- patients can write but cannot read what they have written
Lesion of pure alexia
- often occurs with stroke in posterior cerebral artery
- connected to lesions to left occipital cortex and to posterior sector of the corpus callosum called splenium
Agraphia
- complete loss of previous ability to write
- malfunction in angular gyrus
Atrophy of PPA
Commonly found in anterior temporal lobes, dorsal and ventral white matter tracts between frontal and temporal areas
Three variants of PPA
- Non-fluent/agrammatic PPA
- Semantic PPA
- Logopedic PPA
Atrophy of non-fluent PPA
Inferior frontal gyrus and prefrontal/premotor regions
Semantic PPA
Disorder of semantic memory
Atrophy of semantic PPA
Anterior parts of the temporal lobes
Logopenic PPA
Impaired single-word retrieval in spontaneous speech and naming
Atrophy of logopenic PPA
Left temporal-parietal regions
