کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6265446 | 1614081 | 2010 | 12 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Research ReportInterruption of visually perceived forward motion in depth evokes a cortical activation shift from spatial to intentional motor regions Research ReportInterruption of visually perceived forward motion in depth evokes a cortical activation shift from spatial to intentional motor regions](/preview/png/6265446.png)
Forward locomotion generates a radially expanding flow of visual motion which supports goal-directed walking. In stationary mode, wide-field visual presentation of optic flow stimuli evokes the illusion of forward self-motion. These effects illustrate an intimate relation between visual and motor processing. In the present fMRI study, we applied optic flow to identify distinct interfaces between circuitries implicated in vision and movement. The dorsal premotor cortex (PMd) was expected to contribute to wide-field forward motion flow (FFw), reflecting a pathway for externally triggered motor control. Medial prefrontal activation was expected to follow interrupted optic flow urging internally generated action. Data of 15 healthy subjects were analyzed with Statistical Parametric Mapping and confirmed this hypothesis. Right PMd activation was seen in FFw, together with activations of posterior parietal cortex, ventral V5, and the right fusiform gyrus. Conjunction analysis of the transition from wide to narrow forward flow and reversed wide-field flow revealed selective dorsal medial prefrontal activation. These findings point at equivalent visuomotor transformations in locomotion and goal-directed hand movement, in which parietal-premotor circuitry is crucially implicated. Possible implications of an activation shift from spatial to intentional motor regions for understanding freezing of gait in Parkinson's disease are discussed: impaired medial prefrontal function in Parkinson's disease may reflect an insufficient internal motor drive when visual support from optic flow is reduced at the entrance of a narrow corridor.
Research HighlightsâºRadial expanding optic flow generates the illusion of forward locomotion. âºForward optic flow activates motor circuitry via the lateral premotor cortex. âºMedial prefrontal activation occurs at narrowing radial expanding optic flow.
Journal: Brain Research - Volume 1358, 28 October 2010, Pages 160-171