title: Localizing evoked cortical activity associated with balance reactions: does the anterior cingulate play a role?
abstract: The ability to correct balance disturbances is essential for the maintenance of upright stability. Although information about how the central nervous system controls balance reactions in humans remains limited, recent literature highlights a potentially important role for the cerebral cortex. The objective of this study was to determine the neural source of the well-reported balance-evoked N1 response. It was hypothesized that the N1 is associated with an "error-detection" event in response to the induced perturbation and therefore may be associated with activity within the anterior cingulate cortex (ACC). The localized source of the N1 evoked by perturbations to standing balance was compared, within each participant, to the location of an error-related negativity (ERN) known to occur within the ACC while performing a flanker task. In contrast to the main hypotheses, the results revealed that the location of the N1 was not within the ACC. The mean Talairach coordinates for the ERN were (6.47, -4.41, 41.17) mm, corresponding to the cingulate gyrus [Brodmann area (BA) 24], as expected. However, coordinates for the N1 dipole were (5.74, -11.81, 53.73) mm, corresponding to the medial frontal gyrus (BA 6), specifically the supplementary motor area. This may suggest the N1 is linked to the planning and execution of elements of the evoked balance reactions rather than being associated with error or event detection. Alternatively, it is possible that the N1 is associated with variation in the cortical representation due to task-specific differences in the activation of a distributed network of error-related processing. Subsequent work should focus on disentangling these two possible explanations as they relate to the cortical processing linked to reactive balance control.
authors.affiliation: Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada;
authors.forename: Amanda
authors.initials: A
authors.lastname: Marlin
authors.affiliation: Heart and Stroke Foundation, Canadian Partnership for Stroke Recovery, Sunnybrook Research Institute, Toronto, Ontario, Canada; and Department of Physical Therapy, University of Toronto, Toronto, Ontario, Canada.
authors.forename: George
authors.initials: G
authors.lastname: Mochizuki
authors.affiliation: Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada; Heart and Stroke Foundation, Canadian Partnership for Stroke Recovery, Sunnybrook Research Institute, Toronto, Ontario, Canada; and.
authors.forename: William R
authors.initials: WR
authors.lastname: Staines
authors.affiliation: Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada; Heart and Stroke Foundation, Canadian Partnership for Stroke Recovery, Sunnybrook Research Institute, Toronto, Ontario, Canada; and wmcilroy@uwaterloo.ca.
authors.forename: William E
authors.initials: WE
authors.lastname: McIlroy
mesh_terms: D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology; D004569:Electroencephalography; D004576:Electromyography; D005071:Evoked Potentials; D005260:Female; D006179:Gyrus Cinguli / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D009334:Neck Muscles / Q000502:physiology; D010812:Physical Stimulation; D004856:Postural Balance / Q000502:physiology*; D011930:Reaction Time
keywords: balance; electroencephalography; event-related potentials; reactive control