Tonic and phasic EEG and behavioral changes induced by arousing feedback Chin-Teng Lin a,b , Kuan-Chih Huang a,b , Chih-Feng Chao a,b , Jian-Ann Chen a , Tzai-Wen Chiu a,c , Li-Wei Ko a , Tzyy-Ping Jung a,d, ⁎ a Brain Research Center, University System of Taiwan, Hsinchu, Taiwan b Department of Electrical and Control Engineering, National Chiao-Tung University, Hsinchu, Taiwan c Department of Biological Science and Technology, National Chiao-Tung University, Hsinchu, Taiwan d Institute for Neural Computation, University of California, San Diego, CA, USA abstract article info Article history: Received 24 February 2010 Revised 16 April 2010 Accepted 23 April 2010 Available online 7 May 2010 Keywords: EEG Drowsiness Auditory Feedback Brain dynamics Driving safety Independent component analysis (ICA) This study investigates brain dynamics and behavioral changes in response to arousing auditory signals presented to individuals experiencing momentary cognitive lapses during a sustained-attention task. Electroencephalographic (EEG) and behavioral data were simultaneously collected during virtual-reality (VR) based driving experiments, in which subjects were instructed to maintain their cruising position and compensate for randomly induced lane deviations using the steering wheel. 30-channel EEG data were analyzed by independent component analysis and the short-time Fourier transform. Across subjects and sessions, intermittent performance during drowsiness was accompanied by characteristic spectral augmentation or suppression in the alpha- and theta-band spectra of a bilateral occipital component, corresponding to brief periods of normal (wakeful) and hypnagogic (sleeping) awareness and behavior. Arousing auditory feedback was delivered to the subjects in half of the non-responded lane-deviation events, which immediately agitated subject's responses to the events. The improved behavioral performance was accompanied by concurrent spectral suppression in the theta- and alpha-bands of the bilateral occipital component. The effects of auditory feedback on spectral changes lasted 30 s or longer. The results of this study demonstrate the amount of cognitive state information that can be extracted from noninvasively recorded EEG data and the feasibility of online assessment and rectification of brain networks exhibiting characteristic dynamic patterns in response to momentary cognitive challenges. © 2010 Elsevier Inc. All rights reserved. Introduction Many studies on human sustained attention have confirmed that individuals engaging in monotonous tasks find it difficult or often impossible to maintain a constant level of alertness (Mackworth, 1948). Lapses in alertness become more frequent and prolonged under conditions of sustained wakefulness or lack of sleep, and may have both subtle and catastrophic consequences for operation safety and effectiveness in a wide variety of operational environments. Several studies have demonstrated that fluctuations in human performance and alertness are accompanied by distinct power spectrum changes of the electroencephalogram (EEG) reordered noninvasively from the scalp (Makeig and Inlow, 1993; Makeig and Jung, 1995, 1996; Jung et al., 1997; Makeig et al., 2000; Schier, 2000; Lal and Craig, 2002, 2005; Peiris et al., 2006; Tassi et al., 2006; Davidson et al., 2007; Huang et al., 2001, 2007a,b, 2008, 2009). Jung et al. (1997) further demonstrated the feasibility of accurately estimat- ing shifts in a subject's alertness level, as indexed by changes in their performance level on a simple auditory target detection task, by monitoring the changes in EEG power spectra or other measures. Researches have also attempted to help cognitively challenged individuals combat drowsiness and/or prevent lapses in concentra- tion. Dingus et al. (1997) and Spence and Driver (1998) proposed using warning signals to maintain drivers’ attention. The warning signals could be auditory (Spence and Ho, 2008; Lin et al., 2009), visual (Liu, 2001), tactile (Ho et al. 2005) or mixed (Lee et al. 2006). Belz et al. (1999) compared the efficacy of these warning signals and showed that drivers were less sensitive to visual alarms since the driver needed to pay attention to road conditions and the dashboard. Some studies have demonstrated that a warning stimulus improves the behavioral performance of subjects performing simulated driving experiments (Graham, 1999; Belz et al., 1999; Lin et al., 2009). However, these studies mainly focused on the effects of arousing signals on behavioral performance. To our best knowledge, no study has assessed the EEG correlates of improved task performance following arousing signals. This study explores EEG dynamics and behavioral changes in response to arousing auditory signals presented to individuals experiencing momentary cognitive lapses during a NeuroImage 52 (2010) 633–642 ⁎ Corresponding author. Swartz Center for Computational Neuroscience, Institute for Neural Computation, University of California, San Diego, 9500 Gilman Dr. #0559, La Jolla, CA 92093-0559, USA. Fax: +1 858 822 7556. E-mail address: jung@sccn.ucsd.edu (T.-P. Jung). 1053-8119/$ – see front matter © 2010 Elsevier Inc. All rights reserved. doi:10.1016/j.neuroimage.2010.04.250 Contents lists available at ScienceDirect NeuroImage journal homepage: www.elsevier.com/locate/ynimg