Abnormal subcortical activity in congenital mirror movement disorder with RAD51 mutation

Özet

PURPOSECongenital mirror movement disorder (CMMD) is characterized by unintended, nonsuppressible,homologous mirroring activity contralateral to the movement on the intended side of the body.In healthy controls, unilateral movements are accompanied with predominantly contralateralcortical activity, whereas in CMMD, in line with the abnormal behavior, bilateral cortical activityis observed for unilateral motor tasks. However, task-related activities in subcortical structures,which are known to play critical roles in motor actions, have not been investigated in CMMDpreviously.METHODSWe investigated the functional activation patterns of the motor components in CMMD patients.By using linkage analysis and exome sequencing, common mutations were revealed in sevenaffected individuals from the same family. Next, using functional magnetic resonance imaging(fMRI) we investigated cortical and subcortical activity during manual motor actions in tworight-handed affected brothers and sex, age, education, and socioeconomically matched healthyindividuals.RESULTSGenetic analyses revealed heterozygous RAD51 c.401C>T mutation which cosegregated withthe phenotype in two affected members of the family. Consistent with previous literature, ourfMRI results on these two affected individuals showed that mirror movements were closely related to abnormal cortical activity in M1 and SMA during unimanual movements. Furthermore, wehave found previously unknown abnormal task-related activity in subcortical structures. Specifically, we have found increased and bilateral activity during unimanual movements in thalamus,striatum, and globus pallidus in CMMD patients.CONCLUSIONThese findings reveal further neural correlates of CMMD, and may guide our understanding ofthe critical roles of subcortical structures for unimanual movements in healthy individuals.