FREQUENCY-TAGGING EEG TEST FOR MEASURING SPATIAL ATTENTION IN QIGONG RESEARCH Howe Lin* §¶, Andrew Schneider #, Ramesh Srinivasan +§, and Shin Lin* §¶. Depts. of Developmental & Cell Biology*, Psychiatry & Human Behavior #, Cognitive Sciences +, Biomedical Engineering §, and Susan Samueli Center for Integrative Medicine ¶, University of California, Irvine, CA INTRODUCTION In various types of Qigong meditation practice, the mind is sharply focused on a single thought while in the midst of competing distractions. There have been many studies on the benefits of meditation, but the parameters measured tend to be qualitative and subjective. The aim of this study is to develop a quantitative electroencephalography (EEG) test that could measure a meditator’s ability to focus attention on one set of objects while ignoring another set of competing objects. METHODS Subjects This study, approved by UCI IRB protocol HS# , included subjects who are UC Irvine students and staff between the age of They are healthy and free of any medications by self- report. EEG In the original study of Ding, Sperling and Srinivasan (Cerebral Cortex 16: , 2006), EEG recordings were made with 110 of the 128 channels of a Geodesic Sensor Net (Figure 1). In the present study, recordings were with made with 1 of the channels of a multi- function Holter-type recorder provided by Pre-Ideal Co. of Shanghai (Figure 2), as part of a collaborative arrangement with that company and the Shanghai Qigong Research Institute of the Shanghai University of Traditional Chinese Medicine. Analysis software used was as described in the original study. In both studies, subjects were instructed to focus attention on visual stimuli shown on a computer screen (Figure 3). CONCLUSION RESULTS This work is supported by the Joseph and Sou-Lin Lee Endowment for Chinese Medicine Research. The results of this pilot study suggest that the “frequency-tagging EEG test” could be a quantitative tool for studying whether meditation training can improve mental concentration in the presence of distractions. Furthermore, the test could potentially be useful for gauging the possible beneficial effects of meditation on those who suffer from attention deficit disorder. Figure 1. EEG recording with a 128-channel Geodesic Sensor Net in the previous study by Ding et al. showed that when a subject focused attention on objects flickering at frequencies in the delta band (2-4 Hz), an occipital-frontal network appeared to phase-lock to the flicker, increasing the magnitude of the steady state visual evoked potential (SSVEP). Figure 2. EEG recording with a multi-functional Holter-type instrument using a simplified protocol. The flickering rate of the small white circles in the green ring on the screen was detected by the photocell placed on a special area also flickering at the same rate (note that photocell is in the red rubber holder at upper left corner of the screen and is connected to the Holter recorder). For EEG recording, a single electrode was placed at the midline of the scalp between the parietal and occipital regions (POz), with reference electrodes on the ear lobes and a ground electrode on the center of the forehead. Figure 3. Visual stimuli were shown on the computer screen in the form of two series of random disc search arrays superimposed on two concentric color-marked annuli. The arrays in the green outer annuli (blue arrow is pointing to one small white disc in the array) are electronically set to flicker at a frequency between 2-5 Hz (2.54 Hz in this study) while the ones in the red inner annuli flicker randomly according to a white noise distribution. In each trial, which lasts about 45 seconds, the subject is instructed to focus the eyes on a dot at the center of the screen and attend to the annuli and to detect a target (a triangle) that occasionally appears in the random disc array in the attended annulus while ignoring the target in the array in the other annulus. A typical experiment consists of 12 trials, 6 with the subject attending to one annulus and 6 attending to the other in random order. The presence of a peak at 2.54 Hz was evaluated by visual inspection of the fast Fourier transformation (FFT) power spectrum and a software program was used for automated computing of the power of that peak. This “frequency-tagging EEG test” was used on a number of subjects with experience in meditation, and it was found that when they strongly attended to the outer annulus, there was a sizable FFT peak at 2.54 Hz. When they did not strongly attend to the outer annulus, attended to the inner annulus, closed their eyes, or focused their eyes over the top of the screen, the FFT peak ranged from small to non-detectable. This was also the case when subjects with little or no meditation experience attended to the outer annulus. Flickering rate of stimuli Eyes focused above screen or not strongly attended to flickering stimuli Strongly attended to flickering stimuli