BBS4032 Neuroscience of Speech and Language

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BBS4032 Neuroscience of Speech and Language

• Lecture 5 Acquired language disorders

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Blood supply to the brain
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Blood supply to the brain
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Territories served by cerebral arteries
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Mechanisms of stroke

• Hemorrhagic stroke
• Aneurysm
• Intracerebral vs. subarachnoid

• Ischaemic stroke
• Transient ischaemic attacks
• Occlusion of the blood supply to the brain

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Aphasia

• language disorder resulting from damage to
  portions of the brain responsible for language
• usually occurs suddenly, e.g. as the result of a
  stroke or head injury
• may also develop slowly, e.g. brain tumor,
  primary progressive aphasia
• may impact on any or all of
• expressive
• receptive
• reading
• writing
• may co-occur with dysarthria or apraxia of speech
• most aphasics are in their middle to late years
  men and women are equally affected approximately
  80,000 individuals acquire aphasia each year.
  About one million persons in the United States
  currently have aphasia.

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Damage to Brocas area

• Brocas aphasia, non-fluent aphasia, motor
  aphasia
• Typically
• Better comprehension than production of spoken
  language
• May be syntactic deficits
• Production telegraphic speech, omission of
  function words
• Comprehension inability to reliably interpret
  syntactically complex utterances e.g. passive
  sentences, relative clauses, wh questions
• May be naming deficits (anomia)
• Reading and writing are very variable may
  reflect the same problems as in spoken
  modalities, but may be relatively unimpaired
• Often a contralateral hemiplegia, and motor
  speech deficits are common

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Damage to Wernickes area

• Wernickes aphasia, fluent aphasia, sensory
  aphasia
• Typically
• Better production than comprehension of spoken
  language
• Unimpaired articulation and prosody
• Syntax seems fine (though can be difficult to
  assess)
• Paraphasias (neologistic jargonaphasia) in
  running speech and in confrontation naming
• Reading and writing can be profoundly impaired
• Usually no motor problems

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Examples

• Well this is .... mother is away here working
  her work out o'here to get her better, but when
  she's looking, the two boys looking in other
  part. One their small tile into her time here.
  She's working another time because she's getting,
  too.
• Cinderella and fairy godmother went up and
  Cinderella .. and godfather god mother and ..
  three sisters .. and dressed to the dressed and
  went away and Cinderella said what in the worl'
  happen .. and Cinderella said .. father godmother
  and.. white dress and the punkin er punkin errand
  er six mice and er 12 o'clock er home .. glass ..
  slipper .. glass .. slipper .. 12 o'clock went
  and hurry up Cinderella and one of the glass
  slipper er .. fell .. and um .. prince .. prince
  found the glass slipper and er .. and tomorrow ..
  found the slipper Cinderella three sisters
  appeared but no .. no glass slipper is bad .. and
  Cinderella half sister .. er prince .. er
  Cinderella fit and happily after all.
• Tester "Good!"
• "Yeah. But verbs, and prepositions ...."

From Max Colthearts lecture notes at
http//rosella.bhs.mq.edu.au/max/Language/prod
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Other aphasic deficits

• Large perisylvian lesion ? global aphasia
  impairment of receptive and expressive language,
  impaired repetition
• Damage to arcuate fasciculus ? conduction aphasia
• Fringe area lesions ? transcortical aphasias
• Transcortical motor more effortful speech than
  Brocas, but well-preserved repetition and
  comprehension
• Transcortical sensory reading and writing are
  severely impaired, anomia, semantic paraphasias
• Mixed transcortical (rare) isolation of the
  speech area ? echolalia may be some retained
  language comprehension

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Alexia and agraphia

• Disorders of reading and writing caused by injury
  to the brain
• Reading and writing involve multiple brain
  regions and interconnecting pathways, so alexia
  and agraphia may result from many different
  lesions and may co-occur with various other
  language related deficits
• Alexia and agraphia may occur together or in
  isolation

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Cognitive communication disorders

• Cognition the mental process of knowing,
  including aspects such as awareness, perception,
  reasoning, and judgment
• Agnosia damage to primary sensory areas and
  sensory association cortex ? recognition
  disorders
• Traumatic brain injury
• Lesions affecting the non-dominant hemisphere
  (RHS)
• Dementia (neuro-degenerative disorders affecting
  all aspects of cognitive function)
• NB variability

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Cognitive communication disorder

• Typically affected
• Memory
• Attention
• Affect
• Initiation of communication
• Structure of discourse turntaking, topic
  maintenance
• Pragmatics ambiguity resolution, reference
  assignment, theory of mind
• Appreciation of humor and other indirect uses of
  language
• Typically unaffected
• Syntax, morphology, phonology
• May be affected
• Lexical retrieval
• Cognitive communcaiton disorder typically found
  in
• Traumatic brain injury
• Right hemisphere damage (CVA)
• Dementia

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TBI mechanisms cognitive effects

• Primary brain injury
• Cerebral contusion and lacerationcoup/contre-coup
  
• Lacerations occur through penetrating injury or
  sharp bony projections from the skull
• Diffuse axonal injury - tearing shearing of
  nerve fibers
• Secondary brain injury
• Intracranial hematoma - Infection
• Cerebral edema - Epilepsy
• Raised intracranial pressure
• Cognitive effects
• depend upon the severity of the injury, the
  location of the injury, and the age and general
  health of the patient
• memory, attention, reasoning sensory processing
• communication
• behavioral and mental health components

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RHS deficits

• right frontal lesions ? emotional disinhibition
  and lability
• more posterior damage ? minimization of deficits,
  rationalization
• speech prosody may be flat, or may be
  characterized by unusually high fundamental
  frequency
• excessive verbosity, poor turntaking, digressive
  content, lack of information, excessive attention
  to peripheral or irrelevant detail

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Dementia

• A cognitive syndrome characterized by deficits in
  multiple systems
• Long and short term memory
• At least one of aphasia, apraxia,
  agnosia,impaired executive function (DSM IV)
• Deficits affect social and occupational function
• Most commonly associated with Alzheimers
  Disease, Parkinsons Disease, Lewy Body Disease
• Rarer disorders which often have an impact on
  speech and/or language Huntingtons chorea,
  Friedrichs ataxia, multiple sclerosis

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Alzheimers Disease

• Neurofibrillary plaques and tangles
• Starts in hippocampal complex, spreads throughout
  neocortex
• Initial presentation loss of memory for recent
  events
• Disease progression to frontal and
  temporoparietal cortex ? effects on other
  declarative memory systems, specifically lexical
  and semantic memory
• Early stages conversation, unfinished sentences,
  forgotten communicative intentions
• Middle stages disoriented for place and time,
  increasing difficulties generating a series of
  meaningful ideas ? reduced verbal output
• End stage extensive memory loss, may be
  disoriented for self, minimal problem-solving
  skills, may retain some functional vocabulary

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Alzheimers Disease