Impaired sequence learning in dystonia mutation carriers: a genotypic effect.

Area of Science:

• Neuroscience
• Genetics
• Movement Disorders

Background:

• Abnormal motor sequence learning and cerebellar hyperactivity are noted in non-manifesting DYT1 dystonia mutation carriers.
• The underlying mechanisms and presence in other dystonia types remain unclear.

Purpose of the Study:

• To investigate motor sequence learning and associated brain activation in manifesting DYT1 carriers and DYT6 carriers.
• To correlate these findings with cerebellar pathway integrity and D2 dopamine receptor binding.

Main Methods:

• H2(15)O positron emission tomography (PET) and diffusion tensor imaging (DTI) in DYT1 carriers and controls.
• Task-based fMRI and DTI in DYT6 carriers.
• Correlation analyses between imaging, genetic data, and performance.

Main Results:

• DYT1 carriers (manifesting and non-manifesting) showed similar motor sequence learning deficits.
• DYT6 carriers did not exhibit learning deficits.
• DYT1 carriers displayed increased cerebellar and premotor cortex activation during learning.
• Reduced cerebellar pathway integrity correlated with increased premotor activation and decreased dentate nucleus activation.
• No correlation found between performance/activation and striatal D2 receptor binding.

Conclusions:

• Motor sequence learning deficits and increased cerebellar activation are specific to the DYT1 genotype.
• Findings support DYT1 dystonia as a neurodevelopmental circuit disorder.
• Cerebellar pathway integrity is closely linked to motor learning and premotor cortex function in DYT1 dystonia.