Reduced cortical motor potentials underlie reductions in memory-guided reaching performance.
We used the event-related potential (ERP) methodology to examine differences in neural processing between visually and memory-guided reaches. Consistent with previous findings (e.g., Westwood, Heath, & Roy, 2003), memory-guided reaches undershot veridical target location to a greater extent than their visually guided counterparts. Analysis of the ERP data revealed that memory-guided reaches were associated with reduced potentials over medial-frontal cortex at target presentation and following movement onset. Further, we found that the amplitudes of the potentials over medial-frontal cortex for visually and memory-guided reaches were significantly correlated with the peak accelerations and decelerations of the reaching movements. Our results suggest that memory-guided reaches are mediated by a motor plan that is generated while a target is visible, and then stored in memory until needed--a result counter to recent behavioral theories asserting that memory-guided reaches are planned just before movement onset via a stored, sensory-based target representation.
Department of Psychology and Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada.
Olav
O
Krigolson
Jon
J
Bell
Courtney M
CM
Kent
Matthew
M
Heath
Clay B
CB
Holroyd
D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D005625:Frontal Lobe / Q000502:physiology*; D006801:Humans; D008297:Male; D008568:Memory; D009048:Motor Skills / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*