Right-hemisphere contributions

•      Prosody:  intonation pattern, sound envelope

–   “She did it again?”

•      Affective prosody

–   happy, sad, neutral, angry

 

Right-hemisphere

•      Broca’s…………….Motor aprosodia

•      Wernicke’s…………Receptive aprosodia

•      Transcortical motor…….Transcortical         ………………………….motor aprosodia

•      Transcortical sensory…  Transcortical ………………………….sensory aprosodia

Visual language processing

•      Alexia:  loss of ability to read

•      Agraphia:  loss of ability to write

 

•      Typically occur after damage to angular gyrus in left hemisphere

 

Written language processing

•      Phonological route

–   cat (/k/, /a/, /t/)

–   associate the sound pattern with the concept of “a small furry household pet with claws…”

 

Written language processing

•      Grapheme-to-phoneme correspondence rules

•      Graphemes:  smallest units of written language that are combined to make words

–   c, C, C

–   sounds like /ka/

Written language processing

•      Direct route to reading

–   print is directly associated with meaning

•      Some words are impossible to sound out correctly

•      They are irregular words.

–   Colonel, yacht

 

Written language disorders

•      Surface alexia

•      disruption of direct route

–   cannot link visual form to meaning

–   cannot read irregular words correctly

–   confuse homophones

•   (beat, beet; pane, pain)

•      Lesion:  temporal structures of LH

 

Written language disorders

•      Phonological alexia

•      disrupted phonological loop

•      difficulty with nonwords or words with which they are unfamiliar

•      Lesion:  posterior left hemisphere

 

 

Written language disorders

•      sail/sale; sail/salt (regular words)

•      berry/bury; ferry/fury (irregular words)

•      fex/phects; fex/phox (nonwords)

 

•      surface alexia?

•      phonological alexia?

 

Written language disorders

•      Deep alexia

•      semantic paralexias:  forest……woods

•      difficulty reading abstract words (sympathy, faith) versus concrete words (refrigerator)

•      difficulty reading small function words that serve as grammatical markers

•      Lesion:  left hemisphere (Zaidel, 1990).

 

Disorders of Written Language

•      Alexia without agraphia

Written Language Disorders

•      Phonological agraphia

–   manually or orally spell regular and irregular words to dictation

–   perform poorly with nonwords

•      Lexical agraphia (direct pathway)

–   manually or orally spell nonwords

–   perform poorly with irregular words

Written language disorders

•      Phonological agraphia

–   lesion:  left supramarginal gyrus

•      Lexical agraphia (direct pathway)

–   lesion:  posterior parietal lobe and parieto-occipital junction

 

 

Written language disorders

•      Kana:  sound based and syllabic               phonological route

•      Kanji: logographic

•   symbol stands for concept

•   form of word has no systematic relationship to how it sounds

 

 

 

 

Memory

•      Perceptual knowledge

•      Working memory

•      Knowledge of the world

•      Public events and public figures

•      Specific photographs

 

•      Autobiographic information

Memory

•      HM

–   surgery in 1953

–   removal of medial temporal structures

•   hippocampus

Amnesia

•      Medial temporal lobe regions

–   hippocampus, amygdala, entorhinal and parahippocampal gyri

•      Midline diencephalic region

–   dorsomedial nucleus of thalamus, mamillary bodies

 

Causes of amnesia

•      Herpes encephalitis

•      Vascular accident

•      Hypoxic ischemia

•      Closed head injury

•      Bilateral electroconvulsive therapy (ECT)

•      Alzheimer’s disease

•      Korsakoff’s disease

•      Vascular accident

•      third-ventrical tumor

–    pituitary tumor

Components of amnesia

•      Anterograde amnesia:  after onset of amnesia

•      Retrograde amnesia:  prior to onset of amnesia.

Anterograde amnesia

•      I.  Selective impairment of long-term memory

•      Working memory is intact!!!!!

Working memory is intact!!!

•      Digit span (7 digits)

•   6-5-8-3-2-4-9

•      Extended digit span (8+ digits)

•   6-5-8-3-2-4-9-1

Anterograde amnesia

•      II.  Global nature

•      free recall

•      recognition

•      cued recall

 

•      visual, auditory, somesthetic, olfactory

•      material specific memory disorders

Anterograde amnesia

•      III.  Profound impairment for new events/facts

•      cannot report personal events since injury

•      cannot report public events since injury

•      paired-associate learning

–   obey-inch, crush-dark

Anterograde amnesia

•      IV.  Spared acquisition and expression of skills performance

•      skill learning

–   mirror tracing

–   mirror-image reading task

–   Tower of Hanoi puzzle

•      repetition priming

 

 

Mirror-image reading (Cohen & Squire, 1980)

Tower of Hanoi (Cohen et al., 1985)

Repetition priming (Warrington et al., 1970)

Word-stem completion (Graf, Squire, Mandler, 1984)

•      Motel, cyclone  (stem)

•      cued recall

–   poor performance among amnesics

•      word-stem completion

–   “mot”  what is the first word that comes to mind?

 

 

 

 

Preserved skill learning

•      No recollection of training events

•      No recall of the test materials

•      Poor insight into the nature of the newly acquired skills

 

Anterograde amnesia

•      V.  Sparing of information acquired in an inflexible manner

•      if “normal learning occurs, it is inflexible

•      expressed only in narrow range

•      hyperspecific

Retrograde amnesia

•      I.  Variations in temporal extent

•      II.  Temporal gradient

•      III.  Retrograde amnesia never affects ALL     long-term memory

•      IV.  Skill performance is spared

I.  Temporal extent

•      Temporally extensive retrograde amnesia

–   Korsakoffs, Alzheimers

–   encephalitis, anoxia

 

 

Butters (1970), Squire (1981)

Temporal extent

•      Temporally limited retrograde amnesia

–   ECT, closed head injury

Squire & Cohen (1979)

II.  Temporal gradient

•      Recent memories are affected more than remote memories

•      Shrinking retrograde amnesia

•      Ribot’s Law (1881, 1882)

Shrinking retrograde amnesia

III.  Sparing of information learned early in life

•      Intact knowledge about world

•      Preserved language

•      Perceptual and social skills

•      Spared General Intelligence

IV.  Sparing of skilled performance

•      Dissociation between impaired free recall and priming.

•      Squire et al., (1984)

–   ECT

–   Mirror-image text before and after ECT

Where does amnesia exert effect?

•      Encoding of memory

•      Storage, maintenance, or consolidation

•      Retrieval of memories

Encoding

•      Retrograde amnesia:  disruption of memories that were previously encoded normally.

Consolidation

•      Anterograde amnesia

•      Temporally graded retrograde amnesia

Retrieval

•      Failure to retrieve

•      Loss of stored memories