Dominance Related Issues Flashcards
Cerebral Asymmetry
Biologic landmark of the human cerebral evolution
asymmetrical control for language
Equivalent lesion in right hemisphere
No aphasia
Visual-spatial deficits
RH medial functions
Hypotheses of cerebral dominance
- Equipotentiality: both sides of the brain are equally as capable of serving language
- LH dominance –> diluting effects of RH dominance (left brain becomes more dominant for language around age 5)
- RH for nonlinguistic functions: right hemisphere takes the lead on nonlinguistic functions previously served by LH
- LH damage = interruption of nonlinguistic behaviors
- Intact RH = possible compensatory source in recovery
Implicating Theories: The Coarse Coding Hypothesis
Differences: ways of access to semantic representations & ways semantic representations are suppressed
Implicating Theories: The LH semantic coding
activating small fields, inhibiting all but central features (brings precision)
Implicating Theories: RH Coding
Activation of large semantic fields (brings redundancy – too much info)
Implicating Theories: Suppression Deficit Hypothesis
Reconciliation of multiple meaning hampered due to impaired suppressive strategy (activation of multiple representations for words)
Implicating Theories: Cognitive Resource Hypothesis
Attentional allocation and task demand
RD patients falter on high concentration tasks
Methods to study dominance
lesion-to-stroke data, dichotic listening, tachistoscopic data, commissurotomy
Visual-Tactile association
right hemisphere can match and identify objects through touch
RH recognition, but no naming
patient can read the word “nut” and he will pick up a nut, but cannot say the word
Left Brain
right visual field, left olfaction, speech, writing, main language center, calculation
Right Brain
Right olfaction, spatial abilities, simple language comprehension, nonverbal ideation, left visual field
RH Cog-Communication Profile
characteristics if someone has a lesion in the right brain
Disorders of contextually-based communication from disturbed underlying cognitive, perceptual, and pragmatic processes
- copious output with poor communication
- superficial treatment of information/question
- breakdown on communicative demands
- inappropriate verbal output on careful scrutiny
- often confabulatory speech
- literal interpretation of question
- irrelevant/excessive details
RH communication profile (if lesioned)
- Reduced emotions, melodies, pitch contours, creative language functions
- No organized information, isolation of salient points, or integration of crucial information
- Addresses to but no answer
- Elusive nature of the deficit
Nonlanguage functions of the right brain
- Visual functions: recognition of visual stimuli, image generation, mental rotation, visual-spatial attributes
- Block designs
- Tactile-Visual orientation
- Reproduction (copying, memorization of graphic stimuli, Figure of Rey)
- Visual-Spatial Orientation (spatial object/shape placement, location relationship, map reading, reading/writing deficits –> no space, spelling errors, additional strokes, extra capitalization)
- Orientation to time
- Musical Processing (Naive -RH-vs. Experienced -LH- subjects)
- Attention
- Visual Inattention/neglect
- Affection/Emotion
- Pragmatics
Non-language functions of RH: Musical Processing
Naive subjects vs. Experienced Subjects
- Naive: RH for processing & identification, pitch & melody, dichotic listening, familiar melodies
- Experienced: analytic approach, LH for expression and information processing
Non-language functions of RH: Attention
RH: Neural circuitry for both extra-personal spaces (why there is only left neglect with RH lesion, but never right neglect)
LH: Circuitry for contralateral space (still can access other side because right hemisphere will cover it)
Divided attention
Executive control
Selective attention
Thalamo-cortical
Non-language functions of RH: Visual attention/neglect
unilateral spatial neglect, not interested in events on one side, ignorance of people on affected side, fail to carry out basic self-care tasks, dramatic recover - 85% within 3 days
Affection/Emotion representation in both hemispheres
RH association with experience and expression of negative emotions. Lesion diminishes negative affection (inappropriate jocularity and lack of concerns)
LH association with positive emotions. Lesion = display of catastrophic reactions (anxiety, tears) to failures
Right hemisphere lesion –> prosody, stress, intonation
flat in tone, lack of facial expression/gestures, apathy indifferent reaction, impaired sensitivity to moods in pictures
RH lesion Pragmatic Functions
Insensitive to turn taking, eye contact, context sensitive language, gestures-coverbal properties
Paralinguistic Tasks
Jokes, Metaphors, Idioms
Eliott Ross’ Work: looked at prosody of a variety of patients
Inadequate consideration of paralinguistic functions
Prosody: intonation, melody, pauses, stress, accents, attitudes
Dyprosody: Parkinson’s
Hyperprosody: Manic patients
Hypoprosody: Broca’s aphasics
Kinesis
study of limb, body and facial movements with nonverbal communication
Pantomimes
referential purposes (LH property) motions with meaning
Gestures
non referential - enhance communicative content (don’t carry, but add meaning)
Goodglass and Kaplan ideas regarding Kinesics
- pantomime decoding disorders in aphasics with incomprehension is due to general inability to comprehend symbols
- difficulty in the execution of pantomimes in aphasics with no comprehension disorders
- due to idea-motor apraxia
Diagnosis of RH lesion/damage
No RH sensitive task
•No literal language deficit
•True deficit -on complex tasks
•Testing for: Meaningful organization, Impulsive responses, Trivial details, Differentiation between imp/trivia inf., Assimilation of contextual cues, Depersonalization of events, Literal interpretations to figurative language, Sensitivity pragmatic/context aspects
Components of Evaluations
- Spontaneous use of affection
- Prosodic Content: expression of affective prosody, comprehension of affective prosody
- Visual comprehension of gestural components
- Nonverbal reasoning
Ask: What makes a joke funny, what example similes/metaphors mean, to read sentences while looking for prosody, ask for the meaning of sentences based on the stress patterns, ask to read sentences with suitable emotion
Aphasia in Deaf Signers
sign language & verbal language are two DIFFERENT modes of communication
Interplay between: linguistic and spatial/visual functions (different hemispheric specialization for each process)
Linguistic Nature of ASL
- Hand configurations, facial expressions, and shifting of body positions
- Phonological Code (obeys the physical constraints on motor gestures related with word formation)
- Internal morphology (Packs many morphologically salient units into a single lexical item tied to language modality)
- Complex Syntax (spatially organized)
- Additional attributes (Classifier, verbs, motion, and distinctive location of signs)
Cerebral Dominance relating to static and dynamic stimuli
RH dominance for static signs (LH advantage in hearing subjects)
Changing pattern of cerebral dominance on computer generated moving signs (shift from the RH)
RH lesions in deaf signers
Signers with RH lesion
- no aphasia
- fluent, grammatical, error free signing
- impaired processing of non-language spatial tasks (drawing, lock designs, attention to visual space, line orientation, facial recognition, and visual closures)
RH in signers
Dominance for non-language visual-spatial functions
Aphasia in signers with LH lesion
3 case studies
PD (Wernicke’s aphasia)
1. fluent-type sign aphasia
2. long strings of
motorically facile signs
3. exhibited impaired morphology and syntax
4. preserved phonology and lexical sign properties
KL (Wenicke’s aphasia)
- long strings of signs effortlessly
- wide range of syntactic morphological signs
- phonological impairments making frequent errors in selection of correct hand configuration, place and movement
GD
- grossly impaired sign output
- nonfluent signing reduced to single sign utterances
- largely referential signs without any of the required grammatical and syntactic markings
Extraverbal
accompanying and/or replacing speech
Pantomime
deliberate use of body/manual movements to convey a message
Coverbal or Paraverbal
Behaviors accompanying speech: facial expressions, gestures
Aphasia (pantomime)
impairment of pantomimic expressions and recognition
Paraverbal behavior in aphasia
gestures/facial expressions: generally spared in aphasia
*usually with RH lesion
