Stress Assessment by Prefrontal Relative Gamma

Abstract

Stress assessment has been under study in the last years. Both biochemical and physiological markers have been used to measure stress level. In neuroscience, several studies have related modification of stress level to brain activity changes in limbic system and frontal regions, by using non-invasive techniques such as functional magnetic resonance imaging (fMRI) and electroencephalography (EEG). In particular, previous studies suggested that the exhibition or inhibition of certain brain rhythms in frontal cortical areas indicates stress. However, there is no established marker to measure stress level by EEG. In this work, we aimed to prove the usefulness of the prefrontal relative gamma power (RG) for stress assessment. We conducted a study based on stress and relaxation periods. Six healthy subjects performed the Montreal Imaging Stress Task (MIST) followed by a stay within a relaxation room while EEG and electrocardiographic signals were recorded. Our results showed that the prefrontal RG correlated with the expected stress level and with the heart rate (HR; 0.8). In addition, the difference in prefrontal RG between time periods of different stress level was statistically significant (p < 0.01). Moreover, the RG was more discriminative between stress levels than alpha asymmetry, theta, alpha, beta, and gamma power in prefrontal cortex. We propose the prefrontal RG as a marker for stress assessment. Compared with other established markers such as the HR or the cortisol, it has higher temporal resolution. Additionally, it needs few electrodes located at non-hairy head positions, thus facilitating the use of non-invasive dry wearable real-time devices for ubiquitous assessment of stress.

Quantification of Human Stress Using Commercially Available Single Channel EEG Headset

“…Values of error parameters like Root Mean Squared Error (RMSE) and Root Absolute Error (RAE) are reduced, while computational time is reduced by a factor of 7 in case of low beta waves. In comparison, human stress has been assessed using prefrontal relative gamma by inducing stress [9], whereas, in the proposed method the baseline stress is identified without using a well defined stressor such as MIST.…”

“…A total of twenty-eight participants (66% Copyright c 2017 The Institute of Electronics, Information and Communication Engineers male and 33% female) were involved, with age in the range 22-33 years and a mean of 27.5 years. The experimental design does not rely on an induced stressor like MIST [9], and is proposed to monitor chronic stress. All participants selected for the study were involved with education either as a student or as instructor and no mental illness was reported.…”

“…The brain activity has been shown to vary with the behaviour of normal and depressed subjects in the prefrontal cortex area. Antidepressant treatment medications also effect the prefrontal cortical activities [8], [9]. Among different neural oscillations, higher level of beta waves act as a marker denoting that a person is not in a calm state [10].…”

“…Prefrontal relative gamma has also been used for human stress assessment using Montreal imaging stress task (MIST). The experimental design relies on the stressor and by using the stressed and calm states assess human stress [9].…”

Estado del Arte en Neurotecnologías para la Asistencia y la Rehabilitación en España: Tecnologías Fundamentales

“…El Brain-Computer Interface Lab de la Universidad de Granada (BCI Lab -UGR) ha contribuido en el apartado de la investigación en procesado de EEG a través de varias contribuciones científicas, entre las que destacan: i) una revisión crítica del estado del arte en tendencias y requisitos para la eliminación de artefactos en sistemas BCI modernos (Minguillon et al, 2017) y ii) un estudio relacionado con la medida del estrés a través de ritmos cerebrales (Minguillon et al, 2016b) y la influencia de la luz sobre distintas señales electrofisiológicas (incluyendo EEG) en sujetos sanos (Renedo-Criado et al, 2016).…”