Differences of Functional Connectivity Brain Network in Emotional

Judgment

Mehran Amadlou

, Kazuko Hiyoshi-Taniguchi

, Jordi Solé-Casals

, Hironori Fukuyama

Andrzej Cichocki

2,Ϯ

and François-Benoît Vialatte

1,2,Ϯ

Laboratoire SIGMA, ESPCI ParisTech, Paris, France

LABSP, Riken BSI, Wako-Shi, Japan

Digital Technologies Group. University of Vic, Vic, Spain

Human Brain Research Centres, Kyoto University Graduate of Medicine, Kyoto, Japan

Keywords: EEG, Emotion, Neurodynamics, Synchrony.

Abstract: Using combined emotional stimuli, combining photos of faces and recording of voices, we investigated the

neural dynamics of emotional judgment using scalp EEG recordings. Stimuli could be either combioned in a

congruent, or a non-congruent way. As many evidences show the major role of alpha in emotional

processing, the alpha band was subjected to be analyzed. Analysis was performed by computing the

synchronization of the EEGs and the conditions congruent vs. non-congruent were compared using

statistical tools. The obtained results demonstrate that scalp EEG ccould be used as a tool to investigate the

neural dynamics of emotional valence and discriminate various emotions (angry, happy and neutral stimuli).

1 INTRODUCTION

Neural synchrony of neural assemblies is thought to

be correlated with cognitive functions and mental

representation. Despite years of investigations, much

further work is required to explore the various

functions of oscillations and neural synchrony

(Uhlhaas et al., 2009). This is especially the case for

affective cognition, which is a recent topic of

interest in neuroscience (see Duncan and Barrett for

a review). Judgment is important for decision

making, and involves both cognitive and infra-

cognitive processes. In social cognition, judging the

emotion of another human being is important to

interpret communications. For instance, patients

with emotional judgment disorders, such as patients

suffering from major depression (Grimm et al.,

2006), can have serious social impairments. Our

purpose in this manuscript is to investigate the

neural synchrony of human emotional judgments.

A huge literature emphasizes the role of sub-

cortical areas in emotion processing. However, these

areas do not work independently one from another,

AC and FBV have equal contribution and should be considered

as co-last authors of the present manuscript.

and consequently emotion processing necessarily

involves large-scale networks of neural assemblies

(see e.g. Tsuchiya and Adolfs, 2007).

What would happen if subjects were exposed to

contradictory visual and auditory stimuli? Such

contradiction is termed as a “McGurk effect”

(McGurk and MacDonald, 1976) – the visual and

auditory stimuli do not carry the same message.

Subjects confronted to these emotional stimuli, and

asked to provide feedbacks on their internal

perceptions while their neural activities are recorded,

are confronted to the difficulty of binding

contradictory emotional features.

The purpose of our study was to induce a

controlled perturbation in the emotional system of

the brain by multi-modal stimuli, and to control if

such stimuli could induce reproducible changes in

EEG signal. We use a combination of photos and

voices with congruent or non-congruent emotional

valence. As the synchronization and functional

connectivity plays a major role in flowing

information among brain regions and then for

information processing, we analyze the EEG data

using the functional connectivity, with the goal of

finding the differences of brain dynamics during

judgment in the congruent and non-congruent

276

Amadlou M., Hiyoshi-Taniguchi K., Solé-Casals J., Fukuyama H., Cichocki A. and Vialatte F..

Differences of Functional Connectivity Brain Network in Emotional Judgment.

DOI: 10.5220/0004194002760279

In Proceedings of the International Conference on Bio-inspired Systems and Signal Processing (BIOSIGNALS-2013), pages 276-279

ISBN: 978-989-8565-36-5

 2013 SCITEPRESS (Science and Technology Publications, Lda.)

emotional conditions.

2 METHOD

2.1 Participants

The data were recorded in RIKEN Brain Science

Institute (RIKEN BSI), Tokyo, Japan. 12 young

healthy adults (10 females) were recruited with ages

ranged from 21 to 24 with mean of 21.9 years. The

participants had no history of any

neurological/psychiatric disorders.

As assessed through the Edinburgh handedness

test, all participants were right handed. The Positive

and Negative Affect Schedule (Watson et al., 1988)

was collected for each subject before and after the

experiment, and no subject displayed unusual

PANAS scores (which would have been indicative

of mood disorders).

All participants signed an informed consent

form, and the experiment complied with the Riken

BSI’s ethic review board guidelines.

2.2 Emotional Task

We exposed these subjects to combined audio-visual

stimuli. Stimuli were presented for 2 sec, the

subjects was asked to answer afterwards within a 3

sec window, and then had 5 sec of rest (one trial =

10 sec). The audio-visual stimuli (see Fig. 1) were

composed using simultaneous combinations of

auditory and visual stimuli with three emotional

valences (Angry - A, Happy – H, Neutral - N), either

congruent (e.g. H x H) or non-congruent (e.g. H x

A). Audio stimuli consisted of voice recordings of

the Japanese word ‘arigato’ (thank you) pronounced

with the three different intonations (A, H, and N).

Visual stimuli consisted of faces of women

expressing the same emotional valences, taken from

the JACfee and JACNeuf Japanese-Caucasian photo

databases (Biehl et al., 1997).

The emotional task included 180 stimuli

presenting in a pre-decided random order, so that

two consecutive emotions were always different, and

so that the same number of trials occurred for all

possible pairs of stimuli. For all trials, the task was

to judge if the percept was angry or happy – by

pressing a button.

2.3 EEG Recordings

The EEGs were recorded during the emotional tasks.

They were collected with a 32-channel Biosemi

EEG system with active electrodes in a shielded

room. Sampling rate was fixed at 1024 Hz, notch

filter at 50 Hz and analog band-pass filter between

0.5 and 100 Hz. Fig. 2 shows positions of the

electrodes.

Figure 1: McGurk effect. Visual stimuli (a) are combined

with audio stimuli (b). Subjects will expect congruent

stimuli (b1), where visual and auditory clues are

concordant (e.g. happy face and happy voice). Non-

congruent stimuli (b2), where visual and auditory clues are

discordant (e.g. happy face and angry voice), will induce

distortions in either the visual or auditory perception (this

distortion is termed as a “McGurk effect”).

Table 1: p-values of the inter and intra regions in

discrimination of congruent and non-congruent conditions.

LA RA LP RP

LA 0.33 0.55 0.31 0.14

RA 0.55 0.02

0.04

0.19

LP 0.31 0.04

0.50 0.18

RP 0.14 0.19 0.18 0.10

*: p-value less than 0.05.

2.4 Data Analysis

Fig. 2 shows the topography used in this study,

consisting four regions: Left Anterior (LA), Right

Anterior (RA), Left Posterior (LP), and Right

Posterior (RP). The alpha frequency (8-12 Hz) EEGs

were extracted by applying Butterworth band-pass

filter. Then using the conventional cross-correlation

function, the functional connectivity between each

pair-channel was computed in the alpha band,

DifferencesofFunctionalConnectivityBrainNetworkinEmotionalJudgment

277

according to the following formula:

cov[ , ]

[,]| |

SXY





(1)

Where X and Y are signals of two channels, |x|

indicates absolute value of x,

],cov[ yx is the

covariance of x and y, and



is standard deviation

of x.

Then by averaging the correlation coefficients

over the channels within and between the regions,

the intra- and inter- connectivity of the four regions

(respectively) were computed in the alpha band. The

Mann-Whitney statistical test was used to compare

the differences of the obtained synchronization

values between the congruent and non-congruent

conditions.

Figure 2: Illustration of the brain topography used in this

study, which contains: Left Anterior (LA), Right Anterior

(RA), Left Posterior (LP), and Right Posterior (RP).

3 RESULTS

Fig. 3 shows the mean synchronization values of

inter- and intra- regions in congruent (red triangles)

and non-congruent (blue circles) cognitions. The x-

axis shows the pair regions in the studied

topography and the y-axis shows synchronization

values. It shows all synchronization values in the

non-congruent condition are more than those in the

congruent condition.

Table I presents the p-values obtained by the

Mann-Whitney test for distinguishing the inter- and

intra- regional synchronization values between the

two conditions. The significant p-values (less than

0.05) are related to the right anterior – right anterior

centimeter.

Figure 3: Mean values of inter- and intra- regional

synchronizations in congruent (red triangles) and non-

congruent (blue circles) emotional judgments. The x-axis

shows the pair regions in the studied topography and the

y-axis shows synchronization values.

4 CONCLUSIONS

In this study the differences of brain connectivity in

emotional judgment between congruent and non-

congruent emotional conditions was studied. To the

best knowledge of the authors the current paper

presented the first study on analysis of functional

connectivity in emotional judgment.

It was shown the alpha synchronization in the

overall brain in the non-congruent condition is

higher than that in the congruent condition.

Judgment in the non-congruent condition is more

difficult, compared with the congruent condition,

and therefore the higher alpha synchronization in the

non-congruent condition may be related to the

greater demanding and more effort of the brain for

judging emotions.

The obtained significant p-values between the

conditions in the right anterior – right anterior and

right anterior – left posterior connectivity shows the

ability of the alpha synchronization (in the

associated regions) for discrimination of congruent

and non-congruent conditions. Therefore the alpha

synchronization may have a good potential for

diagnosis of the disorders with deficient emotional

judgments and also it may be useful for their

treatment using EEG neurofeedback training.

LA - LA LA - RA LA - LP LA - RP RA - RA RA - LP RA - RP LP - LP LP - RP RP - RP

0.35

0.4

0.45

0.5

0.55

0.6

0.65

0.7

0.75

INTRA- and INETR- REGIONS

SYNCHRONIZATION VALUE

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ACKNOWLEDGEMENTS

Many thanks go to the International

Neuroinformatics Coordinating Facility (INCF) for

the travel grant provided to support this project. This

work has also been partially supported by the

University of Vic to Dr. Jordi Solé-Casals under the

grant R0904.

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