Abstract
Historically, brain areas implicated in tool and hand processing have been localized by contrasting pictures of tools and hands to pictures of objects or scrambled images using functional magnetic resonance imaging (fMRI). The goal of comparing these conditions in a localizer is to reliably and rapidly identify regions of interest. In contrast to the conventional use of static images, dynamic stimuli, such as videos, may have advantages as they are more engaging than pictures and fully depict the interaction between an effector and its target. The purpose of this project was two-fold: (1) to determine whether video stimuli are more effective than picture stimuli at localizing tool and hand-selective regions in individual participants; and (2) to test whether the nature of activity within these regions are comparable. Healthy subjects were scanned with fMRI while they viewed blocks of video and picture stimuli. The static stimulus set included pictures of tools, hands, objects, and scrambled images. The video stimulus set included short clips of tools interacting with target objects (but with the hand out of the scene), hands manipulating objects, objects in motion, and moving patterns (akin to a scrambled condition). The results show that the video localizer activates a more extensive network of areas than static pictures, particularly in the dorsal visual stream. Moreover, the robust activation for videos facilitated the localization of regions at the individual subject level. By cross-correlating parameter estimates of the video localizer with the picture localizer, we also validate that the video localizer activates the tool and hand-selective areas in a similar fashion as the picture localizer. In sum, using video stimuli better identifies areas involved in tool and hand processing while remaining consistent with the functional activity evoked by static stimuli.
Meeting abstract presented at VSS 2015