Human Functional Magnetic Resonance Imaging Reveals Separation and Integration of Shape and Motion Cues in Biological Motion Processing

Abstract

In a series of human functional magnetic resonance imaging experiments, we systematically manipulated point-light stimuli to identify the contributions of the various areas implicated in biological motion processing (for review, see Giese and Poggio, 2003). The first experiment consisted of a 2 ϫ 2 factorial design with global shape and kinematics as factors. In two additional experiments, we investigated the contributions of local opponent motion, the complexity of the portrayed movement and a one-back task to the activation pattern. Experiment 1 revealed a clear separation between shape and motion processing, resulting in two branches of activation. A ventral region, extending from the lateral occipital sulcus to the posterior inferior temporal gyrus, showed a main effect of shape and its extension into the fusiform gyrus also an interaction. The dorsal region, including the posterior inferior temporal sulcus and the posterior superior temporal sulcus (pSTS), showed a main effect of kinematics together with an interaction. Region of interest analysis identified these interaction sites as the extrastriate and fusiform body areas (EBA and FBA). The local opponent motion cue yielded only little activation, limited to the ventral region (experiment 3). Our results suggest that the EBA and the FBA correspond to the initial stages in visual action analysis, in which the performed action is linked to the body of the actor. Moreover, experiment 2 indicates that the body areas are activated automatically even in the absence of a task, whereas other cortical areas like pSTS or frontal regions depend on the complexity of movements or task instructions for their activation.

Ventral aspect of the visual form pathway is not critical for the perception of biological motion

“…The function and structure of these regions are associated with biological motion perception (11,15,16,20,(41)(42)(43)(44)(45) and their role in biological motion perception has been confirmed in several TMS studies (15,16). In light of this finding, these data permit a stringent comparison between the performance of our ventral patients and that of the brain-damaged patients with lesions to L-pSTS or L-vPMC (the two "critical" lesion groups).…”

“…The predictions are straightforward: if ventral stream integrity and ventral form representations are necessary for the perception of biological motion, then individuals with form perception deficits following damage to the ventral visual cortex [including damage to specific areas implicated in biological motion processing or areas implicated in body form perception (e.g., the EBA) (18)(19)(20)], should be impaired at perceiving biological motion.…”

“…To do so, for each patient we carefully delineated the lesion, assessed the magnitude of the damage, and situated the lesion relative to regions in the ventral, lateral, and middle temporal cortex that are standardly associated with biological motion processing, including body parts and visual motion-sensitive regions (e.g., refs. 13,14,20,[31][32][33].…”

“…Neuropsychological studies in patients and transcranial magnetic stimulation (TMS) studies in normal observers have identified several motion-sensitive areas as critical for biological motion perception, including the posterior superior temporal sulcus (pSTS) and ventral premotor cortex (vPMC) (11,(15)(16)(17), given that a sustained or transient lesion to these regions impairs biological motion perception. However, whether form-sensitive regions in the ventral "form" visual pathway [for example, the extrastriate body area (EBA) (18)(19)(20) in the lateral occipital cortex], which are consistently activated in response to biological motion in neuroimaging studies, play a critical role in biological motion perception remains unknown.…”

Different contributions of visual and motor brain areas during liking judgments of same- and different-gender bodies

“…Previous neuroimaging (Downing et al, 2006;Jastorff & Orban, 2009;Sugiura et al, 2006;Cross et al, 2010;Grossmann et al, 2013), brain stimulation (Urgesi, Candidi, et al, 2007;Candidi et al, 2008) and brain-lesion (Moro et al, 2008) studies have shown that body representations in extrastriate and premotor areas play complementing roles for visual processing of body form and body actions, respectively. For example, a study of Urgesi, Candidi et al (2007) showed that rTMS over EBA impaired performance on a match-to-sample form task but not on a similar task requiring the discrimination of implied motion from the same static body images.…”