Academic journal article Cognitive, Affective and Behavioral Neuroscience

The Role of Kinematics in Cortical Regions for Continuous Human Motion Perception

Academic journal article Cognitive, Affective and Behavioral Neuroscience

The Role of Kinematics in Cortical Regions for Continuous Human Motion Perception

Article excerpt

Published online: 13 August 2013

© Psychonomic Society, Inc. 2013

Abstract It has been proposed that we make sense of the movements of others by observing fluctuations in the kinematic properties of their actions. At the neural level, activity in the human motion complex (hMT+) and posterior superior temporal sulcus (pSTS) has been implicated in this relationship. However, previous neuroimaging studies have largely utilized brief, diminished stimuli, and the role of relevant kinematic parameters for the processing of human action remains unclear. We addressed this issue by showing extended-duration natural displays of an actor engaged in two common activities, to 12 participants in an fMRI study under passive viewing conditions. Our region-of-interest analysis focused on three neural areas (hMT+, pSTS, and fusiform face area) and was accompanied by a whole-brain analysis. The kinematic properties of the actor, particularly the speed of body part motion and the distance between body parts, were related to activity in hMT+ and pSTS. Whole-brain exploratory analyses revealed additional areas in posterior cortex, frontal cortex, and the cerebellum whose activity was related to these features. These results indicate that the kinematic properties of peoples' movements are continually monitored during everyday activity as a step to determining actions and intent.

Keywords Biological motion · fMRI · Natural events · Kinematic properties · Perception

The world is a fluid, ever-changing stream of ongoing activity and movement that the brain must transform into an understanding of intent. How this transformation takes place is a complex problem that can be approached in a bottom-up fashion by exploring the kinematic properties of actions and the brain areas responsive to these properties. The actions in question are the actual physical movements that people perform in order to achieve their intent or goal (Baldwin, Andersson, Saffran, & Meyer, 2008). Much of the research in this area has taken the approach of measuring perceptual judgments or brain activity while presenting contrasting classes of simple elemental movements (e.g., walking and running), utilizing brief video displays or impoverished representations of actions in the form of point-light displays and geometric shapes (cf. Grosbras, Beaton, & Eickhoff, 2012, for a recent meta-analysis). Only a handful of studies have examined the processing of an on-going stream of activity over longer durations (Baldwin et al., 2008; Baldwin, Baird, Saylor & Clark, 2001; Zacks, Kumar, Abrams, & Mehta, 2009) and related this observation to brain activity (Schubotz, Korb, Schiffer, Stadler, & von Cramon, 2012; Zacks, Swallow, Vettel, & McAvoy, 2006). However, these studies neglected to investigate how cortical areas respond to relevant kinematics while viewing human activity. In the present research, we directly explored how the kinematics of observed continuous actions relates to brain activity in cortical regions previously established as areas for the general processing of human action and motion. Our approach closely approximated the processes involved in natural viewing.

Studies comparing different classes of elemental actions with differing kinematics have provided insight into what motion properties relate to judgments in behavioral experiments. For example, studies of male versus female point-light walking movements have revealed the relative contributions of form and motion in judging gender from point-light walkers (Kozlowski & Cutting, 1977;Mather& Murdoch, 1994; Pollick, Kay, Heim, & Stringer, 2005; Troje, 2002). In addition, studies of affective door-knocking movements have shown how the velocity of the wrist can explain the structure of affective judgments from point-light arms (Johnson, McKay, & Pollick, 2011; Pollick, Paterson, Bruderlin, & Sanford, 2001). Examination of on-going activity has been explored in the context of animacy displays (Heider & Simmel, 1944) that investigated what motion properties inform the recognition of intent from two geometric objects interacting. …

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