Constitutional Factors in Stuttering

Flashcards reviewing lecture notes on the constitutional and neurological factors related to stuttering.

Constitutional Factors in Stuttering

Aspects of a person's biological makeup that influence their stuttering.

Family Studies Weaknesses

Researchers only studied families with stuttering without control families; used adults who stuttered asked about family history, excluding recovered children; relied on parent reports, which might introduce errors.

Twin Studies

Show that stuttering occurs more often in both members of identical (monozygotic) twin pairs than in fraternal (dizygotic) pairs, supporting the inheritance hypothesis.

Adoption Studies

Rare but helpful, offering larger contrasts in environmental factors. They can provide insight into the influence of adoptive versus biological family history on stuttering.

Polygenic

Stuttering is thought to be polygenic, meaning it is the result of more than one gene.

GNPTAB, GNPTG, and NAGPA

Mutations of these three genes on chromosome 12 are associated with stuttering. They control enzymes in a cell's lysosome structure involved in recycling cell waste products.

Genome Wide Association Studies

Examine the DNA of a large number of individuals with a disorder and compare them with those without, to reveal genetic differences and pinpoint responsible genes.

Congenital and Early Childhood Trauma Studies

Look at congenital and early childhood trauma as alternative causal explanations of stuttering, accounting for those with no family history.

EEG (Electroencephalography)

Used to measure brain waves and electrical activity in the brain, helping study cerebral dominance for speech in stuttering individuals.

Homologous Areas

Structures in the right hemisphere that are in the same location as left hemisphere areas most active in fluent speakers.

Right Frontal Operculum

Area in the right hemisphere in the same location as Broca's area in the left hemisphere. Often overactive in stutterers.

Cerebral Blood Flow (CBF) Studies

Detect where brain activity occurs by measuring blood flow to those areas, usually using radioactive tracers.

Broca's Area

Responsible for coordinating activity across cortical networks, resulting in speech motor output; often shows decreased activity in stuttering.

Wernicke's Area

Storehouse for the sounds that form words; also often shows decreased activity in stuttering.

Meta Analysis

Statistically analyzing a large number of studies on the same topic and summarizing common findings.

Midbrain Overactivation

Unusually high levels of activity in midbrain structures that may disrupt smooth speech movements, specifically structures of the basal ganglia.

Basal Ganglia

Play an important role in stuttering due to their part in the corticobasal ganglia thalamocortical loop that provides timing signals to the supplementary motor area (SMA).

White Matter Tracts

Less dense in the left hemisphere of stuttering individuals; likely due to right hemisphere takeover of left hemisphere functions.

Fractional Anisotropy

A means of assessing connectivity of white matter tracts, reflecting axon diameter, density, and myelination extent.

Superior Longitudinal Fasciculus (SLF III)

Fiber tract that connects speech output planning areas of the ventral frontal cortex with sensory motor integration areas of the inferior parietal lobe; implicated in stuttering.