Posterior parietal cortex activity reflects the significance of others' actions during natural viewing.
The posterior parietal cortex (PPC) has been associated with multiple stimulus-driven (e.g., processing stimulus movements, providing visual signals for the motor system), goal-directed (e.g., directing visual attention to a target, processing behavioral priority of intentions), and action-related functions in previous studies with non-naturalistic paradigms. Here, we examined how these functions reflect PPC activity during natural viewing. Fourteen healthy volunteers watched a re-edited movie during functional magnetic resonance imaging (fMRI). Participants separately annotated behavioral priority (accounting for percepts, thoughts, and emotions) they had experienced during movie episodes. Movements in the movie were quantified with computer vision and eye movements were recorded from a separate group of subjects. Our results show that while overlapping dorsomedial PPC areas respond to episodes with multiple types of stimulus content, ventrolateral PPC areas exhibit enhanced activity when viewing goal-directed human hand actions. Furthermore, PPC activity related to viewing goal-directed human hand actions was more accurately explained by behavioral priority than by movements of the stimulus or eye movements. Taken together, our results suggest that PPC participates in perception of goal-directed human hand actions, supporting the view that PPC has a special role in providing visual signals for the motor system ("how"), in addition to processing visual spatial movements ("where").
Department of Biomedical Engineering and Computational Science, Brain and Mind Laboratory, Aalto University School of Science, Finland; Advanced Magnetic Imaging Centre, Aalto University School of Science, Finland.
Juha
J
Salmi
Enrico
E
Glerean
Iiro P
IP
Jääskeläinen
Juha M
JM
Lahnakoski
Juho
J
Kettunen
Jouko
J
Lampinen
Pia
P
Tikka
Mikko
M
Sams
D000328:Adult; D001931:Brain Mapping; D053483:Eye Movement Measurements; D005260:Female; D006040:Goals; D006225:Hand; D006801:Humans; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D009483:Neuropsychological Tests; D010296:Parietal Lobe / Q000502:physiology*; D010775:Photic Stimulation; D012815:Signal Processing, Computer-Assisted; D012938:Social Perception; D056345:Theory of Mind / Q000502:physiology; D014741:Video Recording; D055815:Young Adult
behavioral priority; fMRI; human parietal cortex; spatial processing; vision for action