Interhemispheric connectivity and executive functioning in adults with Tourette syndrome

Area of Science:

• Neuroscience
• Neurology
• Psychiatry

Background:

• Structural brain differences in Tourette syndrome (TS) include a smaller prefrontal cortex (PFC) and larger corpus callosum (CC).
• The roles of the PFC and CC in interhemispheric communication and coordination in TS are not fully understood.

Purpose of the Study:

• To investigate the functional roles of the PFC and CC in interhemispheric interference and coordination in adults with TS.
• To examine how structural brain differences in TS relate to performance on tasks measuring motor coordination and cognitive interference.

Main Methods:

• Utilized the verbal-manual interference task and the bimanual Purdue Pegboard test.
• Compared performance in 38 adults with TS and 34 healthy controls.
• Correlated task performance with volumetric measurements of the PFC and CC cross-sectional area.

Main Results:

• TS subjects demonstrated impairments on the bimanual Purdue Pegboard compared to controls.
• The typical left-hand advantage on the dual-task (opposite hemisphere condition) was absent in TS subjects.
• In controls, enhanced left-hand performance correlated with larger PFC volumes, but not CC area.

Conclusions:

• Prefrontal cortex (PFC) dysfunction in Tourette syndrome (TS) may impair executive control over interhemispheric interference.
• Altered interhemispheric coordination and motor control deficits are significant in adults with TS.
• Structural brain abnormalities in TS likely contribute to functional neurological and behavioral differences.