Motor extinction in distinct reference frames: a double dissociation.
OBJECTIVE
Test the hypothesis that right hemisphere stroke can cause extinction of left hand movements or movements of either hand held in left space, when both are used simultaneously, possibly depending on lesion site.


METHODS
93 non-hemiplegic patients with acute right hemisphere stroke were tested for motor extinction by pressing a counter rapidly for one minute with the right hand, left hand, or both simultaneously with their hands held at their sides, or crossed over midline.


RESULTS
We identified two distinct types of motor extinction in separate patients; 20 patients extinguished left hand movements held in left or right space (left canonical body extinction); the most significantly associated voxel cluster of ischemic tissue was in the right temporal white matter. Seven patients extinguished either hand held in left space (left space extinction), and the most significantly associated voxel cluster of ischemic tissue was in right parietal white matter.


CONCLUSIONS
There was a double dissociation between left canonical body extinction and left space motor extinction. Left canonical body extinction seems to be associated with more dorsal (parietal) ischemia, and left canonical body extinction seems to be associated with more ventral (temporal) ischemia.
Department of Neurology, Johns Hopkins University, School of Medicine, Baltimore, MD, USA.
Jennifer
J
Heidler-Gary
Mikolaj
M
Pawlak
Edward H
EH
Herskovits
Melissa
M
Newhart
Cameron
C
Davis
Lydia A
LA
Trupe
Argye E
AE
Hillis
D000368:Aged; D020520:Brain Infarction / Q000150:complications / Q000503:physiopathology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010468:Perceptual Disorders / Q000150:complications / Q000503:physiopathology*; D011596:Psychomotor Disorders / Q000503:physiopathology*