Ch. 7: Is Stuttering Biological? Flashcards
1
Q
Studies
A
See PowerPoint (Slides 2-8)
2
Q
Recent evidence from linkage studies (Kang et al. 2010)
A
- Significant linkage on chromosome 12
- Three relevant gene mutations identified (GNPTAB, GNPTG, and NAGPA)
- Mutations associated with lysosomal storage disorders
3
Q
What might be transmitted?
A
- Structural anomalies?
- Biochemical pathways?
- Brain processing?
- Motor skills?
- Temperament?
4
Q
MRI morphometry (Based on Foundas, et al., 2001)
A
Note extra-gyri in the Sylvian fossa of the stutterer
5
Q
Cerebral Dominance Theory
A
- Proposed stuttering was caused by a lack of cerebral dominance
- Left and right hemispheres compete for control of speech movements
- Asynchrony (mistiming) of neural impulses from both sides of the brain disrupts speech fluency
6
Q
Recent evidence from linkage studies (Kang et al. 2010)
A
- Significant linkage on chromosome 12
- Three relevant gene mutations identified (GNPTAB, GNPTG, and NAGPA)
- Mutations associated with lysosomal storage disorders
7
Q
Differences in brain structure
A
- Wernicke’s area smaller in LH for PWS
- More gyri in Sylvian (LH) region in PWS
- Higher white matter volume in RH
- Reduced white matter integrity in LH
- Deficiencies in LH gray matter volume
- *Most research done w/ adults!
8
Q
Recent research with kids…
[Chang et al., 2008]
A
- Reduced white matter integrity in LH
- Persistent and Recovered CWS: lower gray matter volume in LH speech areas
- But…only CWS who persisted showed lower white matter integrity in LH
- No differences in RH activity and no asymmetry between hemispheres.
9
Q
Neuro-physiologicaldifferences
A
- Overactivation of motor areas
- Especially in RH
- Lower activity in auditory areas
- Auditory suppression bilaterally
- Anomalous RH activity and lateralization
- Decreased connectivity of white matter
- Lower activity in basal ganglia and cerebellum
- More activation in anterior cingulated cortex
10
Q
Auditory Perceptual Theory
A
- Proposed stuttering was caused by defective auditory feedback
- The speaker expects to hear sound earlier than their auditory system feeds it back
- The speaker waits (prolongs) or repeats trying to correct the delay
11
Q
Role of audition
A
- Speech control relevant to audition
- Deaf individuals
- The Lombard effect
- Delayed Auditory Feedback
- Frequency Altered Feedback
- Dichotic listening studies
12
Q
Systems in the Regulation of Movement
A
See PowerPoint
13
Q
Sensory/Motor Dysfunction
A
- Most obvious part of stuttering
- Slower response times (vocal or manual)
- Abnormal movement patterns in jaw, tongue, and larynx (even in fluent speech)
- E.g., timing, muscle activation sequencing force of movements, abnormal breathing patterns, slower rate
14
Q
Brainstem Reflexes: Disorder of Movement Theory
A
- Proposed stutterers have reduced tolerance for a range of oral movements
- If the range is exceeded, brainstem reflex management is upset
- Afferent and efferent signals of speech muscles conflict so stuttering occurs
15
Q
DIVA (Directions into Velocities of Articulators) Model
A
- Stuttering is due to a disorder of sensorimotor speech control
- PWS have unreliable FEEDFORWARD systems so they rely excessively on controlling speech via feedback
- Fluency is disrupted by the attempts to adjust speech movements after commands have been issued
