On the analysis of EEG power, frequency and asymmetry in Parkinson’s disease during emotion processing

Norlinah Mohamed Ibrahim,Ramaswamy Palaniappan,Kenneth Sundaraj,Edgar Mesquita,Marimuthu Satiyan,Murugappan Murugappan,Khairiyah Mohamad,Mohd Iqbal,Rajamanickam Yuvaraj

doi:10.1186/1744-9081-10-12

Abstract

ObjectiveWhile Parkinson’s disease (PD) has traditionally been described as a movement disorder, there is growing evidence of disruption in emotion information processing associated with the disease. The aim of this study was to investigate whether there are specific electroencephalographic (EEG) characteristics that discriminate PD patients and normal controls during emotion information processing.MethodEEG recordings from 14 scalp sites were collected from 20 PD patients and 30 age-matched normal controls. Multimodal (audio-visual) stimuli were presented to evoke specific targeted emotional states such as happiness, sadness, fear, anger, surprise and disgust. Absolute and relative power, frequency and asymmetry measures derived from spectrally analyzed EEGs were subjected to repeated ANOVA measures for group comparisons as well as to discriminate function analysis to examine their utility as classification indices. In addition, subjective ratings were obtained for the used emotional stimuli.ResultsBehaviorally, PD patients showed no impairments in emotion recognition as measured by subjective ratings. Compared with normal controls, PD patients evidenced smaller overall relative delta, theta, alpha and beta power, and at bilateral anterior regions smaller absolute theta, alpha, and beta power and higher mean total spectrum frequency across different emotional states. Inter-hemispheric theta, alpha, and beta power asymmetry index differences were noted, with controls exhibiting greater right than left hemisphere activation. Whereas intra-hemispheric alpha power asymmetry reduction was exhibited in patients bilaterally at all regions. Discriminant analysis correctly classified 95.0% of the patients and controls during emotional stimuli.ConclusionThese distributed spectral powers in different frequency bands might provide meaningful information about emotional processing in PD patients.

Highlights

Parkinson’s disease (PD) is a common progressive neurodegenerative disorder of the central nervous system [1]
Behaviorally, PD patients showed no impairments in emotion recognition as measured by subjective ratings
This study aims to investigate whether differences in EEG frequency bands, induced by the emotional information could be used to discriminate PD patients and normal controls (NCs)

Summary

Introduction

Parkinson’s disease (PD) is a common progressive neurodegenerative disorder of the central nervous system [1]. About 1% of the population over 55 years of age is affected by this disease [2]. Ariatti et al and Yip et al reported problems in categorizing disgust prosody in patients with predominantly right-sided [23,24]. While Ventura et al reported that predominantly left sided patient’s exhibit recognition of sadness emotion [25]. It is not yet clear whether deficits appear in recognizing emotion only in one stimulus modality (i.e., facial expressions [8]) or more (facial displays and prosody [11,23]; facial displays, voices, and verbs [12]). Most studies on emotion recognition mentioned above dealt with behavioral responses (i.e., participants were asked to match, to identify, to judge, or to rate the emotional stimuli) whereas very few studies dealt with physiological measures (i.e., startle eye blink and ERPs)

Methods

Results

Conclusion