Electrophysiological correlates of the processing of different self-aspects of handwritten names

Reiko Sawada,Nobuo Masataka,Motomi Toichi

doi:10.1038/s41598-019-45849-x

Abstract

Humans recognize the self in various visual domains, such as faces, names, and motions, as well as in products, such as handwritten letters. Previous studies have indicated that these various domains of self are represented differently in the brain, i.e., domain-specific self-representation. However, it remains unclear whether these differences in brain activation are due to the processing of different visual features or to differential self-processing among the domains, because the studies used different types of visual stimuli. The present study evaluated event-related potentials (ERPs) while participants were presented with their own and others’ names generated by the participants themselves or someone else. Therefore, the visual stimuli included two domains of self-related information, name and motor agent, but only one type of stimulus (handwritten names). The ERP results show that the amplitudes of the P250 component (250–330 ms) in the posterior regions were smaller for self-generated handwritten names than for non-self-generated handwritten names. The results also show that the amplitudes of the P300 component (350–500 ms) were larger for the self-name than for the non-self-name. These results suggest domain-specific processing of self-related information regarding the name and agent of handwritten stimuli.

Highlights

The self is recognized in various visual domains, such as the face and body parts, in self-related words including written names, in motion, and in products such as handwritten letters
The event-related potentials (ERPs) results show that non-self-generated handwritten names increased P250 (250–330 ms after stimulus onset) amplitudes in the posterior regions relative to self-generated handwritten names regardless of who the names represented
This result is consistent with previous findings showing differences between self-generated and non-self-generated handwritten characters in the posterior regions at around 300 ms after stimulus onset[19,20]

Summary

Introduction

The self is recognized in various visual domains, such as the face and body parts, in self-related words including written names, in motion, and in products such as handwritten letters. Comprehensive reviews have proposed a distinction between the physical and mental aspects of visual-self representation[3,4] This has been demonstrated by previous studies showing domain specificity for visual self-representations, such that brain activity in the cortical midline structures is involved in self-processing and social aspects, including self-appraisal[5] and the judgment of personal traits[6], whereas fronto-parietal regions, in the right hemisphere, are involved in bodily-self-recognition, including recognition of self-face[7,8] and body parts[9]. The goal of the present study was to investigate the existence of domain-specific self-processing using stimuli that were based on a common visual input but comprised two types of self-related information For this purpose, handwritten names were selected as stimuli because they include two aspects of self-related information: name (self-name) and motor agent (self-generated handwriting). Smaller P250 amplitudes for self- versus non-self-handwritten stimuli may indicate that self-generated handwritten characters demand less perceptual load than do non-self-generated handwritten characters in terms of retrieving and accessing the stored structural representations

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Conclusion