Low frequency oscillations during hand laterality judgment task with and without personal perspectives: a preliminary study

Abstract

Sense of personal perspective is crucial for understanding in attentional mechanisms of the perception in "self" or "other's" body. In a hand laterality judgment (HLJ) task, perception of perspective can be assessed by arranging angular orientations and depths of images. A total of 11 healthy, right-handed participants (8 females, mean age: 38.36 years, education: 14 years) were included in the study. The purpose of this study was to investigate behavioural and cortical responses in low-frequency cortical rhythms during a HLJ task. A total of 80-visual hand stimuli were presented through the experiment. Hand visuals were categorized in the way of side (right vs. left) and perspective (1st vs. 3rd personal perspective). Both behavioural outcomes and brain oscillatory characteristics (i.e., frequency and amplitude) of the Electroencephalography were analysed. All reaction time and incorrect answers for 3rd person perspective were higher than the ones for 1st person perspective. Location effect was statistically significant in event-related theta responses confirming the dominant activity of theta frequency in spatial memory tasks on parietal and occipital areas. In addition, we found there were increasing in delta power and phase in hand visuals with 1st person perspective and increasing theta phase in hand visuals with 3rd person perspective (p < 0.05). Accordingly, a clear dissociation in the perception of perspectives in low-frequency bands was revealed. These different cortical strategy in the perception of hand visual with and without perspectives may be interpreted as delta activity may be related in self-body perception, whereas theta activity may be related in allocentric perception.

Keywords: Attention; Body schema; Delta band; Electroencephalogram; Event-related oscillations; Mental rotation; Motor imagery; Response time; Theta band; Time frequency.

Fig. 1

Experimental design

Fig. 2

Grand average waveforms and topographical map of P300 mean amplitude for two conditions

Fig. 3

Delta power responses during the perception of the right- and left-hand regarding 1st and 3rd person perspective

Fig. 4

Theta power responses during the perception of the right- and left-hand regarding 1st and 3rd person perspective

Fig. 5

Delta phase (0–800 ms) locking values during the perception of the right- and left-hand regarding 1st and 3rd person perspective

Fig. 6

Theta phase (0–200 ms) locking values during the perception of the right- and left-hand regarding 1st and 3rd person perspective