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In this study we consider neurophysiological aspects for the assessment of stress-related disorders. EEG Alpha Asymmetry could represent an effective method to be used in the virtual environment. Nonetheless, new protocols need to be defined. In this study herein, we present two methods and a case study.
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EEG Alpha Asymmetry in Virtual
Environments for the Assessment of Stress-
Related Disorders
Pietro CIPRESSO a-b, Andrea GAGGIOLI a-b, Silvia SERINO a-b, Federica
PALLAVICINI a, Simona RASPELLI a, Alessandra GRASSI a-b, Luigi SELLITTI c,
Giuseppe RIVA a-b
a Applied Technology for Neuro-Psychology Lab, Istituto Auxologico Italiano,
Milan, Italy
b Psychology Department, Catholic University of Milan, Italy
c Department of Neurosciences, Istituto Auxologico Italiano, Piancavallo-Verbania,
Abstract. In this study we consider neurophysiological aspects for the assessment
of stress-related disorders. EEG Alpha Asymmetry could represent an effective
method to be used in the virtual environment. Nonetheless, new protocols need to
be defined. In this study herein, we present two methods and a case study.
Keywords. Stress, EEG, Alpha asymmetry, Virtual Reality
There has been growing interest in examining the roles of cognitive appraisal and
emotions in physiological responses to psychological stress [1]. According to Cohen
[2], psychological stress occurs when an individual perceives that the environmental
demands are taxing, or exceed his or her adaptive ability. This gap gives rise to label
oneself as being stressed, and to a concomitant negative emotional response.
In this study herein, we consider neurophysiological aspects for the management
and treatment of stress-related disorders. One of the widely used instruments to analyze
presented aspects is the EEG. In particular, the frontal EEG activation asymmetry has
been generally used, giving evidence that greater left frontal activity seems to be more
highly related to positive mood, whereas greater right frontal activity seems to be more
involved in negative moods, such us stress. According to the recent literature, Alpha
waves seem to be the most useful to study the frontal EEG activation asymmetry. It is
observed that lower Alpha values indicate higher cortical activation.
1. Standard Procedures
One of the most widely used procedures to study EEG alpha asymmetry has been the
use of a sequence of pictures. Visual stimulation has been widely demonstrated to be
effective in the elicitation of specific emotions. The most used and recognized pictures
database is the International Affective Picture System (IAPS), that provide a wide
range of normative emotional stimuli to experimentally test emotions and attention.
The standard method used to present stimuli in an EEG alpha asymmetry study is the
Rapid Serial Visual Presentation (RSVP). Thus the subject wears an EEG and watches
a sequence of images on the monitor.
2. Procedures for Virtual Environments
Virtual Reality is by definition a dynamic environment where subjects are free to move
[4]. Thus an EEG Alpha Asymmetry study could be of the following two types:
Subject enters a virtual room where a virtual monitor projects IAPS images
according to the RSVP method. This method requires the subject to stay
immobilized once the pictures sequences begin. The differences between this
setting and a standard setting is to be deeper studied by researchers, above all
to understand which advantages the use of virtual environments may offer.
Subjects have some tasks in the virtual environment, and a long series of
"events" have been inserted by the researchers. Such a method requires a big
effort to insert events in the virtual environment, and need to define a marker
per each event created in order to accurately synchronize stimuli and EEG
signals. On the other hand, the effort could be balanced by the higher
ecological validity of such experiments. A case study is reported in Fig.1 (sum
of 30 neutral events during a baseline session) and Fig. 2 (sum of 30 stressful
events from a stressful situation exposure).
Figure 1. Sum of EEG Alpha cortical activations on 30 neutral events, during a Baseline session.
Figure 2. Sum of EEG Alpha cortical activations on 30 stressful events from a stressful situation exposure.
A recently funded European project, “INTERSTRESS Interreality in the
management and treatment of stress-related disorders," will take into account these
aspects, verifying frontal EEG activation asymmetry, in the interreality paradigm, i.e.
creating a bridge between the physical and virtual worlds.
3. Acknowledgments
This paper was partially supported by the FP7 European funded projects “Interstress -
Interreality in the management and treatment of stress-related disorders FP7-247685l”
[1] Feldman P, Cohen S, Hamrick N, Lepore SJ. (2004). Psychological stress, appraisal, emotion and
cardiovascular response in a public speaking task, Psychology & Health. 19, pp. 353-368.
[2] Cohen S, Janicki-Deverts D, Miller GE (2007). Psychological stress and disease, Journal of the
American Medical Association, 298(14), pp. 1685-1687.
[3] Coan J.A. and J.J.B. Allen, Frontal EEG asymmetry as a moderator and mediator of emotion,
Biological Psychology 67 (2004) 7-49.
[4] Cipresso P, Raspelli S, Pallavicini F, Grassi A, Balgera A, Gaggioli A, Albani G, Villamira M, Mauro
A, Riva G (2011). Investigations of executive functions using Virtual Multiple Errands Test and
Psychophysiological measures, Journal of CyberTherapy and Rehabilitation 4(2), pp. 259-60.
... The EEG signal amplitude is in the microvolt range. The raw EEG time series data are transformed into the frequency data and classified into five frequency bands: delta band (0.2-4 Hz), theta band (4-8 Hz), alpha band (8-13 Hz), beta band (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30), and gamma band (> 30 Hz). There have been several EEG based studies that analyze stress. ...
... Alpha power asymmetry is defined as the functional difference between the left and the right hemispheres; it measures the difference in EEG band power between the measurements from the homologous electrodes located on these hemispheres [18]. It has been shown that alpha power asymmetry and inter-hemispheric asymmetry indicate mental stress [19]. Previous research has focused on different EEG features, including frequency band power, the ratio of power spectral densities of alpha and beta bands, and cross-correlation between band powers [20]. ...
... The EEG data computation starts by selecting the data from the four electrodes: two electrodes in the left-hemisphere (F3, Fp1), and two electrodes in the right-hemisphere (F4, Fp2) in reference to electrode Fz. For power spectral density (PSD) estimation, the Welch's method, a nonparametric method which is a modified approach of Fast Fourier Transform (FFT) algorithm [33] was used to classify the signals based on frequency into five frequency bands: Delta (0.2 -3 Hz), Theta (3 -8 Hz), Alpha (8 -13 Hz), Beta (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) and Gamma from 30 Hz and up. The alpha band power asymmetry between the left and right hemisphere was calculated using the equation in Table 2. ...
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... More in general the data collection related to the brain is one of the huge field in neuroscience and psychology. In particular neuroimaging techniques received a lot of attention in psychological science and are able to provide a wide spectra of information related to the human thinking related to cognitive, affective and relational aspects (Cipresso et al., 2012b). Moreover, the improvement in the quality of the used methods to automatize the analysis of brain imaging results, provided new access to important information of structural brain and the related connections. ...
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Annual Review of CyberTherapy and Telemedicine (ARCTT) ISSN: 1554-8716 is published annually by the Interactive Media Institute (IMI), a 501c3 non-profit organisation, dedicated to the collaboration of interdisciplinary researchers from around the world to create, test and develop clinical tools and protocols for the medical and psychological community. IMI realizes that the mind and body work in concert to affect quality of life in individuals and works to develop technology that can be effectively used to improve the standards and reduce the cost of healthcare delivery worldwide.
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Frontal EEG asymmetry appears to serve as (1) an individual difference variable related to emotional responding and emotional disorders, and (2) a state-dependent concomitant of emotional responding. Such findings, highlighted in this review, suggest that frontal EEG asymmetry may serve as both a moderator and a mediator of emotion- and motivation-related constructs. Unequivocal evidence supporting frontal EEG asymmetry as a moderator and/or mediator of emotion is lacking, as insufficient attention has been given to analyzing the frontal EEG asymmetries in terms of moderators and mediators. The present report reviews the frontal EEG asymmetry literature from the framework of moderators and mediators, and overviews data analytic strategies that would support claims of moderation and mediation.
Investigations of executive functions using Virtual Multiple Errands Test and Psychophysiological measures
  • P Cipresso
  • S Raspelli
  • F Pallavicini
  • A Grassi
  • A Balgera
  • A Gaggioli
  • G Albani
  • M Villamira
  • A Mauro
  • G Riva
Cipresso P, Raspelli S, Pallavicini F, Grassi A, Balgera A, Gaggioli A, Albani G, Villamira M, Mauro A, Riva G (2011). Investigations of executive functions using Virtual Multiple Errands Test and Psychophysiological measures, Journal of CyberTherapy and Rehabilitation 4(2), pp. 259-60.