Exploring Biological Motion Processing in Parkinson's Disease Using Temporal Dilation.

Ruihua Cao,Yanghua Tian,Xing Ye,Xingui Chen,Long Zhang,Kai Wang,Panpan Hu,Xianwen Chen,Marina A Pavlova

doi:10.1371/journal.pone.0138502

Abstract

Biological motion (BM) perception is the compelling ability of the visual system to perceive complex animated movements effortlessly and promptly. A recent study has shown that BM can automatically lengthen perceived temporal duration independent of global configuration. The present study aimed mainly to investigate this temporal dilation effect of BM signals in Parkinson’s disease (PD) patients. We used the temporal dilation effect as an implicit measure of visual processing of BM. In all, 32 PD patients (under off-therapy conditions) and 32 healthy controls (HCs) participated in our study. In each trial, an upright BM sequence and an inverted BM sequence were presented within an interval in the center of the screen. We tested both canonical and scrambled BM sequences; the scrambled ones were generated by disturbing the global configuration of the canonical ones but preserving exactly the same local motion components. Observers were required to make a verbal two-alternative forced choice response to indicate which interval (the first or the second) appeared longer. Statistical analyses were conducted on the points of subjective equality (PSEs). We found that the temporal dilation effect was significantly reduced for PD patients compared with HCs in both canonical and scrambled BM conditions. Moreover, no temporal dilation effects of scrambled BM were shown in both early- and late-stage PD patients, while the temporal dilation effect of canonical BM was relatively preserved in the early stages.

Highlights

Johansson (1973) first demonstrated the phenomenon of biological motion (BM) perception [1]
We found that the temporal dilation effect was significantly reduced for Parkinson’s disease (PD) patients compared with healthy controls (HCs) in both canonical and scrambled BM conditions
We investigated the temporal dilation effect of visual processing of BM signals in PD patients, which is a novel approach to studying BM processing

Summary

Introduction

Johansson (1973) first demonstrated the phenomenon of biological motion (BM) perception [1]. He showed that a set of twelve moving light points attached to the joints of the body sufficed to create a rich perception of a moving human figure. When the point-light displays are presented upside down, adequate perception is strongly impaired in a manner called the “inversion effect” [2,3,4]. BM provides socially relevant information that includes the identity of the moving stimulus, his or her actions, intentions, and even emotions. The human visual system is fine-tuned to detect and extract socially relevant information from BM rapidly and effortlessly. A deficit in BM processing may have wide-ranging consequences for social perception and interpersonal functioning

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