Posterior parietal cortex activity reflects the significance of others' actions during natural viewing

• Published in: Human brain mapping 2014-09, Vol.35 (9), p.4767-4776
• Main Authors: Salmi, Juha, Glerean, Enrico, Jääskeläinen, Iiro P., Lahnakoski, Juha M., Kettunen, Juho, Lampinen, Jouko, Tikka, Pia, Sams, Mikko
• Format: Article
• Language: English
• Subjects: Adult; behavioral priority; Biological and medical sciences; Brain Mapping; Eye Movement Measurements; Female; fMRI; Goals; Hand; Health participants; human parietal cortex; Humans; Investigative techniques, diagnostic techniques (general aspects); Linear Models; Magnetic Resonance Imaging; Male; Medical sciences; Motion Perception - physiology; Nervous system; Neuropsychological Tests; Parietal Lobe - physiology; Photic Stimulation; Public health. Hygiene; Public health. Hygiene-occupational medicine; Radiodiagnosis. Nmr imagery. Nmr spectrometry; Signal Processing, Computer-Assisted; Social Perception; spatial processing; Theory of Mind - physiology; vision for action; Young Adult
• ISSN: 1065-9471; 1097-0193
• DOI: 10.1002/hbm.22510

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”). Hum Brain Mapp 35:4767–4776, 2014. © 2014 Wiley Periodicals, Inc.