EEG Mu Rhythm in Typical and Atypical Development

Summary

Assessment of the EEG mu rhythm provides a unique methodology for examining brain activity and when combined with behaviorally based assays, can be a powerful tool for elucidating aspects of social cognition, such as imitation, in clinical populations.

Abstract

Electroencephalography (EEG) is an effective, efficient, and noninvasive method of assessing and recording brain activity. Given the excellent temporal resolution, EEG can be used to examine the neural response related to specific behaviors, states, or external stimuli. An example of this utility is the assessment of the mirror neuron system (MNS) in humans through the examination of the EEG mu rhythm. The EEG mu rhythm, oscillatory activity in the 8-12 Hz frequency range recorded from centrally located electrodes, is suppressed when an individual executes, or simply observes, goal directed actions. As such, it has been proposed to reflect activity of the MNS. It has been theorized that dysfunction in the mirror neuron system (MNS) plays a contributing role in the social deficits of autism spectrum disorder (ASD). The MNS can then be noninvasively examined in clinical populations by using EEG mu rhythm attenuation as an index for its activity. The described protocol provides an avenue to examine social cognitive functions theoretically linked to the MNS in individuals with typical and atypical development, such as ASD. 

Introduction

Electroencephalography (EEG) is an effective, efficient, and noninvasive method of assessing and recording brain activity. As neurons fire in the brain, the resulting voltage can be amplified, recorded, and graphically represented. The temporal resolution of EEG allows for the analysis of even brief changes in the oscillation patterns of the brain, as well as the analysis of the brain’s response to specific stimuli.

Despite being the oldest brain imaging technique, dating back to the late 19^th century, EEG still has wide-ranging applicability. While functional magnetic resonance imaging (fMRI) h....

Protocol

The following protocol adheres to the guidelines of the University of Washington institutional review board.

1. Electrophysiological Assessment

1. Preparation of Session
   1. Room preparation: place the manipulandum (see Figure 1), a wooden block with a sensor attached, which sends a time-stamped marker to acquisition software when it is grasped, on the table within grasping reach of the participant. Activate EEG acquisition software and begin “new session” (Figure S1).
   2. Net preparation: warm solution of distilled water (1 L), potassium chloride (1 tablespoon), and....

Results

Typical adults, children and infants have consistently demonstrated mu rhythm during both the execution and observation of actions across a variety of paradigms and stimuli^5,14-30. Attenuation in this frequency band is consistently localized across central electrodes (Figure 3) indicating that this is not reduction of alpha power which is recorded at other scalp regions. Similarly, attenuation in this frequency during the observation of movement is limited to the observat.......

Discussion

The successful acquisition, processing, and analysis of electrophysiological data related to the mu rhythm and the application to clinical populations requires 1) the application of EEG methodological tools, 2) careful artifact detection and data reduction, 3) accurate identification of the mu rhythm, and 4) accurate characterization of the clinical population and identification of appropriate control groups.

Appropriate EEG methodology requires properly functionin.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Geodesic EEG System	EGI	N/A	Any EEG system, not only EGI based systems, is applicable for the described study
MATLAB software	MATLAB	N/A	Any mathematical, statistical software that can work with matrices is applicable
Netstation software	EGI	N/A	Any EEG acquisition software is applicable for the described study
Manipulandum	custom	N/A	Any object that is coregistered with data acquisition software to signal a successful grasp