Aphasia Flashcards
Cerebral hypoxia
deficiency of needed oxygen to the brain
Caused by smoke inhalation, head trauma, choking, carbon monoxide poisoning, drowning, drug overdose, stroke
Middle cerebral hypoxia
inattentiveness, poor decision making, reduced coordination
Severe hypoxia
unresponsive, fall into coma, stop breathing
Considered brain dead when only blood pressure and heart beat
Blood supply to the brain
Aorta (main body to heart) Internal carotid (80% blood supply) Vertebral artery (20% blood supply)
Vertebral arteries
Converge near the base of the pons to form basilar artery, splits to form the posterior cerebral arteries
Internal carotids
Branch from middle cerebral arteries and anterior cerebral arteries
Middle Cerebral Artery
Supplies the lateral surface of the brain
Includes language region (Broca’s, Wernicke’s)
Primary sensory cortex, motor cortex
MCA Deficits
Paralysis of one side of body/one side of face
Dysarthria
Left MCA - aphasia
Right MCA - r. hem language disorder
Anterior Cerebral Artery
Supplies the front and medial cortical surfaces of the frontal and parietal lobes
Incl prefrontal cortex, primary motor cortex
ACA Deficits
Higher order cognitive functions (prefrontal cortex) Motor difficulties (legs and feet)
Posterior Cerebral Arteries
Supplies the anterior and inferior temporal lobe, inferior and medial occipital lobe
Stems from basilar artery
PCA - Deficits
Visual processing difficulties
Cortical blindess
Alexia (write but not read)
Vertebral Basilar System (Posterior Circulation)
Stems from the subclavian arteries
- continue along the ventrolateral surface of medulla after entering the skull
Forms the single basilar artery; travels along the midline of the pons
VBS - Deficits
Stroke (manipulation of the neck)
Fine motor control/coordination
Motor speech disorders
Blood Supply to the Cerebellum
Superior cerebellar artery
Anterior inferior cerebellar artery
Posterior inferior cerebellar
Stroke
“An insult to the central nervous system on a primary vascular basis”
Vessel is either blocked/bleeds causing part of brain to be deprived to be deprived of oxygen/nutrients
Affect the cerebral hemispheres, sub-cortical structures, the brainstem, the cerebellum, spinal cord
Impact of Stroke
Onset is sudden
Brief disruption of blood supply causing lasting effect on brain tissue
Leading cause of aphasia
Ischemic Stroke
Lack of blood flow (due to clot) depriving it of fuel and oxygen
80-85% of stroke
Hemorrhagic Stroke
Release of blood into the brain and spaces within the cranium
Collection of blood cuts off connecting pathways
Causes localised and generalised pressure on surrounding tissue
Biochemical substances released during/after the bleed affect brain tissue
Thrombosis
Obstruction of blood flow due to clot
Causes ischemic stroke
Embolism
Substance travels through blood vessel (not necessarily a clot)
(Causes ischemic stroke)
Forms of haemorrhagic stroke
Intracerebral haemorrhage
Subarachnoid haemorrhage
Subdural/epidural haemorrhage
Subarachnoid haemorrhage
Intracerbral haemorrhage
Bleeding from a vessel within the brain
HBP - puts pressure on artery walls
Subarachnoid haemorrhage
Rupture of aneurysm, bleeding from an arteriouvenous malformation
Subdural/epidural haemorrhage
Occurs within those layers in the skull
Subarachnoid
Aneurysm (most common) Arteriovenous malformation (AVM)
Signs of stroke
Sudden severe headache with no cause
Numbness/weakness to the face, arm/leg, especially one side of the body
Alteration of conscious state
Speech disturbance
Visual field deficits
Cognitive inpairment including confusion, trouble speaking/understanding
Motor/sensory dysfunction - trouble walking, dizziness, loss of balance/coordination, poor motor control of face
Transient Ischemic Attack
Temporary/brief focal cerebral event that doesn’t lead to permanent damage
Due to temporary blockage of brain vessel
Symptoms short lived; seconds - 24 hours
Majority of TIAs resolve in less than an hour
Broca’s Aphasia
Production
- non-fluent; some apraxia/dysarthria
Reduced syntactic complexity
Strong reliance on memorised formulaic expressions
Impairment of closed-class words (grammatical elements)
Comprehension
- relatively preserved
Repetition
- Disrupted (esp longer words, grammatical words)
- Better than spontaneous speech, still disrupted
Wernicke’s Aphasia
Production
- fluent, sometimes excessive
- frequent paraphasias (phonemic/semantic errors)
- Morphological and syntactic substitutions
- Strong reliance on memorised formulaic expressions
- Poor insight into deficits
Comprehension
- Impaired for sentences
Repetition
- Disrupted; word choice, phonology, grammar
Conduction Aphasia
Production
- more fluent vs Brocas, less than Wernicke’s
- frequent paraphasias (phonemic errors)
Comprehension
- Relatively preserved
- Problems occur with long complex sentences with high STM demands
Repetition
- Disrupted (esp longer words)
Global Aphasia
Production - Severely impaired Comprehension - Severely impaired Repetition - Severely impaired
Anomia
Production - fluent, with hesitations - marked word finding difficulties Comprehension - relatively preserved Repetition - Relatively preserved
Localisation Theory
Mental operations are localised to discrete brain regions, represented by distributed networks of brain areas
Localisation Theory - Assumptions
Direct correspondences can be drawn between brain structure and function
Localisation Theory - Evidence
Tan - autopsy revealed involvement of Wernicke’s area as well
Focal Broca area infractions with no Broca’s aphasia
Agrammatism with no damage to Broca’s area
(Feature of Broca’s aphasia) Lead to questioning of direct mapping of language functions to structural areas
Localisation Theory - Limitations
Specific regions may be relevant for language, but not dedicated soley for language
Functions don’t rely on a single discrete part of the brain
Connectionist View of Aphasia
Representations are activation patterns Processing is spreading activation Triangle model - bidirectional flow - single phonogical system and orthographic system for input and output - No lexical representation
Connectionist View of Aphasia - Positives
Provides a conceptual model for how semantic representations activated the lexical representation which activate the phonological representations
Cognitive Neuropsychological Approach
Individual pattern of breakdown is more useful than relying on group data
Phonological Input Lexicon
Deciding which is a real word; must access knowledge about phonology of words
Consult mental dictionary = phonological input lexicon
Orthographic Input Lexicon
Deciding real word - must access orthographic knowledge (spelling)
Phonological Output Lexicon
If the word has been pronounced before, phonological representation is accessed using phonological knowledge
Word frequency - Critical Variables
High freq words are easier vs low freq at lexical level
(frequency effect)
Assessment - compare performance on high and low freq. words
Imageability - Critical Variables
Highly imageable are easier to access
Esp if difficulties at semantic level
Imageability effect
Assessment - compare performance on abstract vs concrete words
Word length - Critical Variables
Shorter words easier to produce vs longer if difficulties with phonological assembly
Words with regular spelling are easier vs irregular spelling
Lexicality - Critical Variables
Real words easier than non-words
Semantic errors
“Leopard” - tiger
Phonological errors
“Truck” - trup/stuck
Unrelated errors
“Chair” - bottle
Semantic Lexicon - Disorder and Behaviour
Disorder - category loss/degradation - generalised degradation - access problem Behaviour - failure to define/sort words into specific categories - semantic paraphasias
Phonological Lexicon - Disorder and Behaviour
Disorder - Impaired word form representation - disorder of phonological control Behaviour - anomic circumlocation - neologistic jargon - semantic errors
Phonological Assembly -Disorder and Behaviour
Disorder
- Impaired phoneme selection and seriation
Behaviour
- phonemic paraphasia
Phonetic planning - Disorder and Behaviour
Disorder
- Impaired phoneme selection and seriation
Behaviour
- Apraxia of speech
Articulation
Disorder
- Neuromotor damage
Behaviour
- Dysarthria
Negatives of CNP
Reliance on single-case studies
Lack of info in model; consists of descriptive, box-and-arrow diagrams
Doesn’t provide insight into how therapy works
Positives of CNP
Fine-grained theory driven examination of language and cognitive processing
Identification of indiv. strengths and weaknesses to identify impairments, facilitate possible targets for treatment
Main principles of modularity
Functional modularity
Anatomical modularity
Universality of cognitive systems
Subtractivity
Anatomical modularity
some localisation in the brain
Universality of cognitive systems
Everyone essentially has the same cognitive systems
Subtractivity
Brain lesions destroy, damage or impair components of the normal cognitive system
