Functional MT + lesion impairs contralateral motion processing.
Human motion processing region MT + is retinotopically organized with perception of and attention to motion in the right visual field preferentially associated with left MT + activity and vice versa. However, the degree to which MT + is crucial for motion processing is uncertain. We report an epilepsy patient with visual symptoms early in his seizure evolution and a left temporal-occipital seizure onset electrographically in whom we hypothesized a functional left MT + lesion. The patient was impaired in his right but not left visual field on a hemifield motion attention task and demonstrated worse performance on a hemifield picture identification task when pictures implying motion were presented in the right as opposed to the left visual field. Functional MRI (fMRI) during a full-field motion detection task activated right MT + but failed to activate left MT + despite activating both left and right MT + in each of 10 controls. Furthermore, fMRI during a hemifield motion attention task also showed a lack of left MT + attention effects in the patient. Together these results suggest that MT + is necessary for normal motion processing.
Moo
Lauren R
LR
Neuropsychology Laboratory, Department of Neurology, Massachusetts General Hospital, Boston, MA02114, USA. lmoo@partners.org
Emerton
Britt C
BC
Slotnick
Scott D
SD
D001288:Attention; D001931:Brain Mapping / Q000379:methods*; D007839:Functional Laterality; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D009778:Occipital Lobe / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods; D014793:Visual Cortex / Q000502:physiology; D014794:Visual Fields / Q000502:physiology; D014796:Visual Perception