title: Cerebellar gray and white matter volume and their relation with age and manual motor performance in healthy older adults.
abstract: OBJECTIVE
  Functional neuroimaging and voxel-based morphometry studies have confirmed the important role of the cerebellum in motor behavior. However, little is known about the relationship between cerebellar gray (GMv) and white matter (WMv) volume and manual motor performance in aging individuals. This study aims to quantify the relationship between cerebellar tissue volume and manual motor performance.
  
  
  METHODS
  To gain more insight into cerebellar function and how it relates to the role of the primary motor cortex (M1), we related cerebellar GMv, WMv, and M1v to manual motor performance in 217 healthy older individuals. Left and right cerebellar GMv and WMv, and M1v were obtained using FreeSurfer. The following motor measures were obtained: grip force, tapping speed, bimanual visuomotor coordination, and manual dexterity.
  
  
  RESULTS
  Significant positive relationships were observed between cerebellar GMv and WMv and grip strength, right cerebellar WMv and right-hand tapping speed, right cerebellar WMv and dexterity, M1v and grip strength, and right M1v and left-hand dexterity, though effect sizes were small.
  
  
  CONCLUSIONS
  Our results show that cerebellar GMv and WMv are differently associated with manual motor performance. These associations partly overlap with the brain-behavior associations between M1 and manual motor performance. Not all observed associations were lateralized (i.e., ipsilateral cerebellar and contralateral M1v associations with motor performance), which could point to age-related neural dedifferentiation. The current study provides new insights in the role of the cerebellum in manual motor performance. In consideration of the small effect sizes replication studies are needed to validate these results.
authors.affiliation: School of Kinesiology, University of Michigan, Ann Arbor, Michigan.
authors.forename: Vincent
authors.initials: V
authors.lastname: Koppelmans
authors.forename: Sarah
authors.initials: S
authors.lastname: Hirsiger
authors.forename: Susan
authors.initials: S
authors.lastname: Mérillat
authors.forename: Lutz
authors.initials: L
authors.lastname: Jäncke
authors.forename: Rachael D
authors.initials: RD
authors.lastname: Seidler
mesh_terms: D000368:Aged; D000375:Aging / Q000473:pathology* / Q000502:physiology; D002531:Cerebellum / Q000473:pathology*; D005260:Female; D007839:Functional Laterality; D066128:Gray Matter / Q000473:pathology*; D018737:Hand Strength; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D009044:Motor Cortex / Q000473:pathology; D009048:Motor Skills; D009929:Organ Size; D066127:White Matter / Q000473:pathology*
keywords: MRI; cerebellum; gray matter; motor function; volume; white matter