title: Cognitive context determines dorsal premotor cortical activity during hand movement in patients after stroke.
abstract: OBJECTIVE
  Stroke patients often have difficulties in simultaneously performing a motor and cognitive task. Functional imaging studies have shown that movement of an affected hand after stroke is associated with increased activity in multiple cortical areas, particularly in the contralesional hemisphere. We hypothesized patients for whom executing simple movements demands greater selective attention will show greater brain activity during movement.
  
  
  METHODS
  Eight chronic stroke patients performed a behavioral interference test using a visuo-motor tracking with and without a simultaneous cognitive task. The magnitude of behavioral task decrement under cognitive motor interference (CMI) conditions was calculated for each subject. Functional MRI was used to assess brain activity in the same patients during performance of a visuo-motor tracking task alone; correlations between CMI score and movement-related brain activation were then explored.
  
  
  RESULTS
  Movement-related activation in the dorsal precentral gyrus of the contralesional hemisphere correlated strongly and positively with CMI score (r(2) at peak voxel=0.92; P<0.05). Similar but weaker relationships were observed in the ventral precentral and middle frontal gyrus. There was no independent relationship between hand motor impairment and CMI.
  
  
  CONCLUSIONS
  Results suggest that variations in the degree to which a cognitive task interferes with performance of a concurrent motor task explains a substantial proportion of the variations in movement-related brain activity in patients after stroke. The results emphasize the importance of considering cognitive context when interpreting brain activity patterns and provide a rationale for further evaluation of integrated cognitive and movement interventions for rehabilitation in stroke.
authors.affiliation: Movement Science Group, School of Life Sciences, Oxford Brookes University, Gipsy Lane, Headgington, Oxford, OX3 0BP, UK. adennis@brookes.ac.uk
authors.forename: Andrea
authors.initials: A
authors.lastname: Dennis
authors.forename: Rose
authors.initials: R
authors.lastname: Bosnell
authors.forename: Helen
authors.initials: H
authors.lastname: Dawes
authors.forename: Ken
authors.initials: K
authors.lastname: Howells
authors.forename: Janet
authors.initials: J
authors.lastname: Cockburn
authors.forename: Udo
authors.initials: U
authors.lastname: Kischka
authors.forename: Paul
authors.initials: P
authors.lastname: Matthews
authors.forename: Heidi
authors.initials: H
authors.lastname: Johansen-Berg
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003071:Cognition / Q000502:physiology*; D005260:Female; D006225:Hand / Q000294:innervation / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000033:anatomy & histology / Q000503:physiopathology*; D009068:Movement / Q000502:physiology*; D010291:Paresis / Q000209:etiology / Q000503:physiopathology* / Q000534:rehabilitation; D020521:Stroke / Q000150:complications / Q000503:physiopathology*; D000071939:Stroke Rehabilitation