The Mindfulness Meditation Effect on Brain Electrical Activity:

Stress Assessment, Concentration State and Quality of Life

Pedro Morais

1,2,3 1

and Carla Quintão

1,2 2

Department of Physics, Faculty of Sciences and Technology, Universidade NOVA de Lisboa, Lisbon, Portugal

Laboratory for Instrumentation, Biomedical Engineering and Radiation Physics, UNL, Lisbon, Portugal

Biomedical Engineering Doctoral Program, UNL, Lisbon, Portugal

1 RESEARCH PROBLEM

Modern societies are oriented towards a model of life

that is increasingly competitive, agitated and

demanding. A large part of the population responds,

on a daily basis, quickly and under a great amount of

stress to their professional responsibilities and

household chores, with little time to relax. A pre-

programmed way of life, constantly pressed, where

there is no opportunity to think, rest or contemplate

everything that is good around us, imposes timings,

which are contrary to one’s natural rhythms. The

consequences of this, at first, include changes in the

quantity and quality of sleep; in food intake habits,

that tend to become inadequate and unhealthy; and in

fatigue, that becomes chronic. Over time, the harmful

effects to one´s health are numerous. Heart problems;

body aches; weight loss or gain; hormonal changes;

or even difficulty in social relationships, with

concomitant isolation from others are common

complaints (Institute of Medicine, 2006).

Psychological disorders as depression, anxiety and

stress begin, either alone or together, to take a

significant role in our daily lives. In Europe, Portugal

stands out as a country in which these types of health

problems are prevalent. One third of its population

reports some degree of health perturbations caused by

accelerated life styles (Health General Directorate,

2017). This vulnerable and sickly way of living

contributes to an increasingly depressed and anxious

society. It leads also to the rise of drug consumption,

often self-medicated, relieving the symptoms in

certain cases, but not addressing the source of the

problems.

The aforementioned scenario constitutes a serious

public health concern, requiring urgent measures. We

believe that such measures should involve the

development of brain mechanisms of self-regulation.

https://orcid.org/0000-0002-1774-7093

https://orcid.org/0000-0003-1015-4655

Mindfulness meditation emerges as a part of the

solution, easily accessible to the average citizen, not

only from a therapeutic viewpoint, but mostly as a

proactive way to prevent and respond to some of the

health disturbances that affect that part of the

population. Such approach is a mental technique for

controlling the individuals’ mental state and, in

consequence, their own well-being. Mindfulness is

rooted on the principle that the non-judgmental

observation of the present, disconnected from past

experiences and future expectations, calms down

one´s own mind.

Recent studies have identified brain areas

correlated with the positive effects of meditation

(Davidson, R.J et al, 2003). However, the underlying

neuronal mechanisms of such correlates are still

unclear, and it is evident that rigorous and systematic

scientific research is needed, to fully understand the

role of meditation onto mental states and neuronal

positive adaptation. Hence, future studies should

address the relation between conscious Mindfulness

meditation and neuronal circuit changes. In addition,

most published work, in this area, perform only

comparative studies between experimental and

control groups at one single instant, disregarding the

intrinsic dynamic nature of the training and use

effects of meditation. Besides, electrophysiologic

signals, such as electroencephalogram (EEG),

electrocardiogram (ECG) and electrodermal activity

(EDA) are often studied individually (Tang, Y.Y. et

al, 2015), whereas we believe that the information

produced by each technique may validate and

potentiate the understanding of the phenomena at

study. Finally, self-assessment surveys are often not

included in studies, preventing a reliable relation

between neurophysiologic data and changes in

quality-of-life, which could be easily and

unequivocally reported by the participants.

Morais, P. and Quintão, C.

The Mindfulness Meditation Effect on Brain Electrical Activity: Stress Assessment, Concentration State and Quality of Life.

In Doctoral Consortium (BIOSTEC 2019), pages 20-27

Thus, an integrated and longitudinal research,

including personal surveys, is required to accurately

assess potential mental health benefits of Mindfulness

meditation.

2 OBJECTIVES

The current PhD study, in Biomedical Engineering,

intends to show that Mindfulness meditation practice,

with its goal of being "here and now", improves one’s

mental health, as demonstrate via attentive self-

regulation and a decrease in anxiety, depression and

stress. Through a thorough data collection and

analysis strategy, we aim to conclude that this type of

meditation can be used as a valid approach to deal

with clinical disorders, which affect a large portion of

the population.

3 STATE OF THE ART

Mindfulness meditation emerges as an easy-to-use

way to promote an individual’s well-being, as well,

as a technique to prevent and treat a specific range of

widespread mental illnesses. It has evolved

throughout the world, and gave its practitioners a

significant improvement in quality of life (Kabat-

Zinn, J., 2003). Due to the good results achieved, it

was adopted in some countries as a curricular

discipline in secondary education and used in medical

care (Center for Mindfulness in Medicine Health Care

and Society, 2018).

Research made in this area, in particular those

using functional MRI during cognitive tasks,

identified individual regions, associated to specific

functional changes after meditation, including the

prefrontal cortex; insula; hippocampus; and

amygdala (Kilpatrick, L.A., 2011). These areas were

also mentioned in brain volumetric studies using

structural MRI, in which variations of brain mass

were reported. However, the published research did

not always agree. In some cases, the conclusions were

even contradictory.

EEG, with its particularly high temporal

resolution, has also been used as a non-invasive

technique to analyse spatiotemporal data from brain

electrical activity, providing relevant information

about neural networks (Michel, C.M et al, 2004).

These studies showed that practicing Mindfulness

meditation leads to an alpha power increase and also

showed that focusing one’s attention can be

associated with an increased gamma activity

(Hinterberger, T., 2014).

Although, there has been significant progress and

maturation in Mindfulness meditation research, a

careful review of the reported outcomes, reveals that

it is necessary to deepen the neuroscientific

knowledge about brain function changes and how

Mindfulness can be effectively used in the context of

mental disorders and to improve one’s quality of life

(Van Dam, N.T. et al, 2018).

4 METHODOLOGY

The current study is based on a set of tasks, involving

visual stimuli, concentration tests and stress-inducing

challenges. 30 individuals were submitted to a

Mindfulness Based Stress Reduction (MBSR) course

and evaluated at regular intervals, in a period of 12

weeks (Mindfulness Based Stress Reduction, 2018).

In 4 scheduled sessions, EEG, ECG and EDA signals

were recorded, while subjects performed the

aforementioned tasks. In each session, subjects filled

in three questionnaires, assessing their current quality

of life; mood state profile; and depression, anxiety

and stress levels. Through exploration of the

recorded physiological data, we will search for

functional changes that may occur in the autonomic

and central nervous systems, as a result of the

Mindfulness practice. After attending the course,

each subject may experience one or several of the

following: changes in their heart rate and sweating

levels; the ability to concentrate; as well as in the

control of individual emotional responses to their

surroundings. Assuming that such effects are

established, it will be important also to assess how

they can be operationalized, not only to treat mental

disorders, but also to help prevent them. In addition,

it is important to note that the proposed strategy

would have the added benefits of a low-cost

intervention, in a positive life-changing approach,

with no known negative side effects.

4.1 Participants Recruitment and

Characterization

Since this project is being conducted in the Faculty of

Sciences and Technology of Nova University of

Lisbon, the recruiting information for the study was

made available via a poster in one of the most affluent

places of the school, and an announcement made via

e-mail for all students, teachers and staff. Both

contained a link where all interested volunteers could

obtain more detailed information about the MBSR

The Mindfulness Meditation Effect on Brain Electrical Activity: Stress Assessment, Concentration State and Quality of Life

course (duration, name of the instructor, schedule…),

as well as the kind of award certificate of attendance.

An immediate pre-selection was made after

completing a small inquiry, which excluded

candidates who had already Mindfulness training or

who did not have total availability to attend the

complete course, spanning the 12 weeks, and

participate in the 4 sessions of data collection. After

15 days, 30 healthy candidates were selected, filling

all vacancies.

During the MBSR 5 subjects gave up, due to

health problems or with no explicit justification, so

the final population for the study comprised 25

subjects (mean age = 26.0, SD = 7.07, 9 of which

were male), consisting of 23 university students and

2 university staff. The latter had higher education.

4.2 Self-Assessment Surveys

Three self-assessment surveys were used in this

research: World Health Organization Quality of Life

(WHOQOL); Profile Of Mood States (POMS); and

Depression, Anxiety and Stress Scale (DASS). All

answers were given through online forms,

specifically created for this study and with

authentication by assigning a unique and non-

transferable identification code.

4.2.1 World Health Organization Quality of

Life

WHOQOL stems from a collaborative project,

assessing individual quality of life from an

international perspective. It emerged from a

definition statement that quality of life is “the

individual's perception and position in life in a

cultural context and value system in which he lives

and in relation to his goals, expectations, standards

and concerns” (World Health Organization,

Measuring Quality of Life, 1995). The WHOQOL-

100 consists of 100 questions, in this case adapted to

Portuguese population, that assess six dimensions:

physical, psychological, independence level, social

relations, personal environment and spirituality

beliefs. The inquiry begins with 42 questions

determining whether the individual has already

experienced certain things related to positive feelings

of happiness and contentment. It is classified as

"Nothing" to "Most", corresponding to a scale of

values of 1 to 5, respectively. The next 13 questions

are related to the daily activities, evaluating whether

the subject has experienced, or was able to do certain

things, such as washing or eating, with the qualitative

classification of "Nothing" to "Completely". The 3

phase of the survey includes personal life

qualification, with 34 questions assessing whether the

individual felt happy, satisfied or good about various

aspects of their life, ranging from "Very Unsatisfied"

to "Very Satisfied". The friendship support is assessed

through the following three questions, referring to the

frequency with which one felt or experienced things

like friends’ support or the sensation of insecurity.

"Never" to "Always" are the limits of their qualitative

evaluation. The work-related analysis is assessed

through 4 questions, about the daily activities, which

are most time and energy consuming. It includes

volunteer work, full time, paid or not, and also

housework. Here the classification goes from

"Nothing/Very dissatisfied" to "Completely/Very

satisfied". The 6

survey group, comprises 4

questions, addressing mobility, and refers to

individual's physical ability to move on his own and

accomplish things that he wants and needs to do. The

questions are answered on a scale between "Very Bad/

Nothing/Very Unsatisfied" and "Very Good/Very

Much/Very Satisfied". Finally, 4 questions regarding

religious beliefs, principles and personal values are

addressed, varying the return between "Nothing" to

"Many". The answers to the 100 questions are given

based on the last two weeks of the individual's

experience. The quality of life is evaluated

quantitatively in the six domains, from 1 to 5. The

greater the result obtained (the sum of all answers) the

healthier the subject.

4.2.2 Depression, Anxiety and Stress Scale

DASS was designed with 42 items and adapted to

Portuguese with a subset of 21 items (Pais-Ribeiro, J.

L. et al, 2004). This scale was developed for adults,

evaluating a set of feelings and emotions, grouped in

3 basic structures: anxiety, depression and stress.

Anxiety includes skeletal muscle effects, autonomic

system arousal, subjective experiences, and

situational anxiety. Depression encompasses lack of

interest or involvement, discouragement, life

devaluation, self-deprecation, and inertia. Finally,

stress encompasses the nervous excitement, agitation,

irritability, impatience and difficulty in relaxation.

The questions are put up via an online form,

evaluating each symptom separately, and addressing

only the last week, on a scale of points from 0 to 3.

The final evaluation is calculated on the 21 answers

divided into three groups. The minimum value is 0

and the maximum value is 21, corresponding to the

most negative emotional and affective state. The final

assessment assigns the grade "Normal", "Soft",

"Moderate", "Severe" and "Severe extremity".

DCBIOSTEC 2019 - Doctoral Consortium on Biomedical Engineering Systems and Technologies

4.2.3 Profile of Mood States

POMS assesses emotional variations and

psychological well-being of an individual (McNair,

D. M., Lorr, M., & Droppleman, L. F, 1971). This

evaluation instrument, initially used in psychiatric

populations, has been used in non-clinical

populations since it is easy to answer and quick to use.

In the advanced survey, the Portuguese adaptation

was used with 42 adjectives, identifying six mood

state factors: Tension/Anxiety, represents increased

musculoskeletal tension and concern;

Depression/Melancholy, describes the emotional

state of sadness, loneliness, unhappiness and

discouragement; Hostility/Anger, portrays a mood of

anger or antipathy towards others; Vigour/Activity,

represents the state of energy and physical and

psychological vigour; Fatigue/Inertia, expresses a

state of fatigue, inertia and reduced energy; and

finally Confusion/Disorientation, corresponds to a

low lucidity and confused state. All questions, put

through an online form, evaluate the person’s state

during the last week, in a scale from 0 to 4, with the

correspondence: 0 - "Nothing", 1 - "A little", 2 -

"Moderately", 3 - "Enough" and 4 - "Very much".

After completed, the level of disturbance in mood

state of an individual is calculated, via the sum of the

tension states, depression, hostility, fatigue and

confusion, from which the state of vigour is

subtracted. To avoid a negative final result, the value

100 is added. Hence, 74 and 244 will correspond to

the minimum and maximum limits of the scale,

respectively. The state of humour is so much healthier

the smaller the final result obtained.

4.3 Psychological Challenges and

Stress Factors - Cognitive, Motor

and Visual

Auditory and visual stimulations, as well as stress

challenges elicit in a given person a specific

emotional reaction and, consequently, different

biological signals. After Mindfulness practice it is

expected that these outcomes vary, when compared to

those recorded before meditation training. In

particular, Mindfulness experts report greater latency

in reactions to stimuli, as well as less intensification

in the emotions, which should be reflected somehow

in the electrophysiological signals recorded. A set of

three tasks were developed specifically to evaluate

the differences in performance, within the recorded

signals before and after Mindfulness practice.

During the study, 4 data collection instances were

set: the first, in the week before the beginning of the

Mindfulness course; the second, 4 weeks after that;

the third, in the last week of the course, 4 weeks after

the beginning of the recordings; and the fourth

session, 2 months after completing the MBSR course.

In these four sessions participants were subject to

the same type of stimuli and recorded the same bio

signals.

4.3.1 Cognitive Stimuli

The first approach used is a 5 minutes cognitive task.

The subject is sitting comfortably, with his eyes

closed, and is asked to remain the first 30 seconds

with his head free of any thoughts. After a sound

notification, in the next 30 seconds, the subject should

perform a mental countdown from 100, with a 3-in-3

step. It is not intended to be fast in this counting

procedure, but rather to keep concentrated in the task.

These two 30-second cycles are repeated 5 times.

4.3.2 Motor Challenge

The second stimulus is a motor challenge, which also

lasts 5 minutes. A Python application was developed

to build a winding path (Figure 1), which will be

presented in a monitor. The subject has a cursor,

which should be made to go through the path, using

the mouse, without transposing its limits. If this

happens, the process is reset, returning the cursor to

the departure place, with a concomitant stress sound

to be heard.

Figure 1: Stress Route application, designed to evaluate

motor behaviour under stress conditions. The task lasts for

5 minutes.

As an addition stress factor, the cursor movement is

artificially deformed, using a sine trigonometric

function, to deviate it from the root. This stressor is

applied in order to avoid cursor "jump" impulses,

whenever the user moves the mouse after few

The Mindfulness Meditation Effect on Brain Electrical Activity: Stress Assessment, Concentration State and Quality of Life

moments of inactivity. The cursor trace is stored in a

CSV file for further analysis.

4.3.3 Visual Stimuli

There are several types of images that negatively

influence an individual. Records of violence, erotic

scenes and wild animals, such as snakes or spiders,

often annoy those who visualize them. In this work,

the International Affective Picture System (IAPS)

database, developed by the National Institute of

Mental Health Center for Emotion and Attention, at

the University of Florida, will be used (ILang, P.J.,

Bradley, M.M., & Cuthbert, B.N., 2008). A Stress-

Image Python application was developed to present

the respective images to the subjects. From the 1200

images that compose IAPS, 300 stress images were

chosen, divided into 4 experimental sessions and

maintaining the same sequence. The idea is that

subjects will be facing equally disturbing images

throughout sessions, without repeating them, which

could lead to some level of habituation. For 10

minutes, the subject stays sitting comfortably in front

of a monitor, and observes each image, which is

shown for 6 seconds, followed by 2 seconds of a black

background interval between images.

4.4 Neurophysiologic Signals

Acquisition (EEG, ECG, EDA)

During all tasks described above, neurophysiologic

data were collected through EEG, ECG and EDA.

Electroencephalographic signals were recorded using

a 32 active channels gTEC Nautilus system, with an

acquisition rate of 250Hz (g.tec Nautilus, 2018). The

raw data was saved using the proprietary software

gRecorder. The electrodermal activity and

electrocardiogram were acquired using a wireless 4-

channel BioSignalsPlux system (BioSignalsPlux,

2018). This device collects and digitizes the signals

from each sensor and transmits them via Bluetooth to

a computer to be recorded, with a 16-bit resolution

and a 500Hz sampling frequency per channel. The

raw data was recorded via the OpenSignals software,

also from BioSignalsPlux. All three signals can be

visualized in real-time, which allows identifying,

already during the recording stage, possible problems

with the data, such as signal loss or electric artifacts.

4.5 Processing and Data Analysis

The three surveys, WHOQOL, POMS and DASS,

were processed, to determine the various scores for

mental states of each subject. The data acquired

through gNautilus and BioSignalsPlux was converted

to a format compatible with Matlab. With the stored

information, which amounted to 7GB, it was

necessary to perform a first visual analysis. Thus, a

dedicated interface was developed that allows the

combined visualization of all four sessions signals at

once. Figure 2 displays the ECG and EDA signals, of

one particular subject, recorded during the

visualization IAPS task.

Figure 2: Matlab interface to visualize, per subject, EDA

and ECG results in all four sessions of the study.

This interface also gives the possibility to use an

algorithm for the detection of ECG peaks, which

allows for the calculation of the Heart Rate

Variability (HRV). The procedure is shown in Figure

3. Regarding the EDA data analysis, Ledalab, a very

useful function from Matlab, allowed the

differentiation between Skin Conductance Response

(SCR) and Skin Conductance Level (SCL), which in

turn is paramount to identifying relevant EDA peaks,

and calculating their respective amplitude (see Figure

4) (Ledalab, 2014).

Figure 3: ECG peak detection and HRV calculation.

DCBIOSTEC 2019 - Doctoral Consortium on Biomedical Engineering Systems and Technologies

Figure 4: Area identification for SCR and SCL, together

with the estimated EDA peaks, using the Ledalab Matlab

module.

Finally, and to explore data collected during motor

stimulation, an application was built to calculate the

number of times the subject failed their trailing task;

identifies where the failures occurred; and displays

the total average distance reached (all illustrated in

Figure 5).

Figure 5: Mouse recorded tracking during motor

stimulation, with the location and identification of fails and

total distance reached.

By comparing the various recordings made

throughout all four sessions, one may assess the

benefits of the proposed MBSR course.

5 EXPECTED OUTCOMES

Figure 6 illustrates, in a schematic form, the

workflow presented in previous sections. The process

used in this research project consists of the collection

of neurophysiologic data, via EEG, ECG and EDA,

throughout four sessions, occurring in different

phases of a MBSR course.

Figure 6: Proposed Biomedical Engineering PhD

methodology, intended to show the effects of Mindfulness

meditation practice to well-being surrogate

electrophysiological data.

In each session, patients are subjected to three

different stimuli: Cognitive, Motor and Visual. At the

same time, each patient completes three surveys:

WHOQOL, POMS and DASS contributing to the

differentiation of pathologies and consistency of the

results obtained. Finally, the expected functional

changes in the cerebral cortex are studied, as well as

the possible advantages of practicing this meditation

technique, such as an increase in attention self-

regulation, a decrease in levels of anxiety, depression

and stress and an increase in quality of life.

The Mindfulness Meditation Effect on Brain Electrical Activity: Stress Assessment, Concentration State and Quality of Life

6 STAGE OF THE RESEARCH

After the 25 patients collection phase, it was possible

to conclude that the results obtained in the 3 inquiries,

during the 4 sessions, immediately gave rise to an

optimistic confirmation of the expected conclusion:

Mindfulness meditation can be useful to prevent and

to respond to some psychological health disturbances.

The analysis of the 3 surveys, for each session, allow

the identification of different groups of participants,

defined by their mental general state. Knowledge of

this may help the analysis of the respective

neurophysiologic signals, as their behaviour is

expected to differ from one another. This work stage

is still in progress.

In parallel, the first study performed in EDA,

using visual stimuli, shows a general average

tendency for a greater emotional control after

Mindfulness meditation training (see Figure 7).

Figure 7: Average EDA results, using visual stimuli, from

the 25 subjects and in each of 4 recording sessions.

EDA values decrease with the evolution of the

course, which is a good indicator of the

aforementioned increased control. Similarly, it is

expected that, after ECG processing and analysis, one

observes a decrease in heart rate, as the MBSR course

progresses.

Then, the EEG analysis will be performed,

observing if any spatial-temporal alteration occurs

within the typical EEG bands: theta, alpha, beta and

gamma.

Finally, it is expected that the integration of all

available information will bring new insights on the

effects of Mindfulness practice in the brain function

and in coping with stress.

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The Mindfulness Meditation Effect on Brain Electrical Activity: Stress Assessment, Concentration State and Quality of Life