BOLD Signal Change during Driving with Addition Task using fMRI

Ji-Hun Jo, Hyung-Sik Kim, Soon-Cheol Chung and Mi-Hyun Choi

Research Institute of Biomedical Engineering, Department of Biomedical Engineering,

School of ICT Convergence, Engineering, College of Science & Technology, Konkuk University,

268 Chungwandae-ro, Chungju-si, South Korea

Keywords: Driving with Addition Task, BOLD Intensity, fMRI.

Abstract: This paper uses a driving wheel and pedal (working as an accelerator, brake) equipped with an MR-

compatible driving simulator at a speed of 80 km/h when driving and when driving while performing

secondary tasks in order to observe differences in neuronal activation (BOLD signal change). The

experiments consisted of three blocks, each block consisting of both a Control phase (1 min.) and a Driving

phase (2 min.). During the Control phase, the drivers were instructed to look at the stop screen and not to

perform driving tasks. During the Driving phase, the drivers either drove or drove while performing addition

tasks at 80 km/h. The intensity of activated voxels increased in the addition task condition compared to the

driving condition in insula.

1 INTRODUCTION

Quantitative observation of cerebral nerve activation

using functional Magnetic Resonance Imaging

(fMRI) is performed using two concurrent

assessments: changes in the area of cerebral nerve

activation (the number of activated voxel) based on

Blood Oxygenation Level Dependent (BOLD) and

changes in the size of cerebral nerve activation (the

intensity of activated voxel). The changes in the area

of cerebral nerve activation is an index assessing a

specific region of the cerebral nerve activity or

variation in the area of cerebral nerve activation,

while the changes in the size of cerebral nerve

activation is an index of the signal intensity of

activated voxels within the same region. Therefore,

either of the two methods can be selectively used for

the studies with different primary purposes.

Many people nowadays frequently perform extra

tasks (i.e. audio and navigation control, smartphone

usage, eating, or carrying on a conversation) while

driving. Recent neuroimaging studies have utilized

fMRI to elucidate the neural activation under driving

with extra task (Just et al., 2008; Uchiyama et al.,

2012; Newman et al., 2007; Graydon et al., 2004).

The subjects – while driving and performing an

extra task simultaneously, in comparison with

driving – exhibited reduced neural activation in the

regions related to the spatial processing, visual

spatial attention, movement planning and execution,

action planning and motor control, but increased

neural activity in the regions related to performing

extra tasks (Just et al., 2008; Newman et al., 2007;

Uchiyama et al., 2012). Nonetheless, these previous

studies have primarily focused on observing the

changes in the area or the region of cerebral

activation. In order to more clearly understand the

effects of performing simultaneous extra tasks on

driving, not only the differences in the neural

network activities but also the difference in the size

of neural activity in the same region should be

assessed via additional studies.

This study aims to observe the differences in the

intensity of activated areas between driving and

driving with a simultaneous additional task.

2 METHODS

In total, 10 adult male subjects in their 20’s (mean

age of 23.0±1.2) with mean driving experience of

2.6±1.8 years and without medical condition or

history were selected for this study. Prior to the

study participation, the subjects were provided with

information regarding the purpose and the content of

the study, and were controlled for other external

factors that can affect either driving or cerebral

nerve activation – including smoking, alcoholic

100

Jo, J., Kim, H., Chung, S. and Choi, M.

BOLD Signal Change during Driving with Addition Task using fMRI.

DOI: 10.5220/0007376501000103

In Proceedings of the 12th International Joint Conference on Biomedical Engineering Systems and Technologies (BIOSTEC 2019), pages 100-103

ISBN: 978-989-758-353-7

drinks, and coffee. Practice driving runs were

performed until the subject became familiar with the

environment of driving simulator and could drive

without an accident.

The developed MR-compatible driving simulator

was composed of a driving wheel, an accelerator and

a brake pedal (Figure 1). Driving environment was

created using a software from Lightrock

Entertainment. The subject used both hands to

manipulate the driving wheel and right foot to press

on the accelerator or brake pedal, and was asked to

drive at a constant speed of 80km/h without making

lane changes.

Figure 1: MR-compatible driving system.

The experimental design is composed of three

blocks (Figure 2) – with one block consisting of the

control phase (1 minute) and the driving phase (2

minutes). During the control phase, the subjects

were asked to stare at a still frame without driving.

During the driving phase, the subjects were either

asked to focus on driving at 80km/h or perform

both driving at 80km/h and an additional task at the

same time. All subjects participated in the study

under both conditions (driving, driving with an

additional task). The speed of the vehicle was

provided on the bottom left corner of the stimulator

screen so that the subject could maintain the

vehicle speed of 80km/h.

Figure 2: Experimental design.

The additional tasks were composed of

mathematical calculations where the sum of the 2-

digit numbers do not exceed 100 and the task

requires carrying. There were 10 questions in each

block, resulting in 30 questions of additional tasks in

total. The investigator provided the additional task

questions verbally via an audio system attached on

the MR system, and the subject reported verbal

responses to the questions.

The regions of cerebral nerve activation under

each condition (driving, driving with an additional

task) were calculated in comparison to the control

phase. Using a voxel exhibiting the greatest

statistical significance for activation as the standard,

a 5x5x5 region was selected. In this selected region,

the mean value of BOLD signal according to each

condition and each phase was calculated. In order to

analyze the variations in the cerebral nerve

activation during the stimulation phase in

comparison with the resting phase under each

condition, BOLD % change was calculated using the

following equations:

ܤܱܮܦ % ܿhܽ݊݃݁ = {(Driving phase – Control

phase) / Control phase} x 100(%)

In order to assess the difference in BOLD %

change at the selected regions under each condition,

Independent t-test (PASW 18) was performed.

3 RESULTS

The 8 regions that were commonly activated under

both condition included inferior frontal gyrus,

inferior parietal lobule, inferior temporal gyrus,

insula, lingual gyrus, precentral gyrus, precuneus,

and superior temporal gyrus. In comparison to

driving condition, only the one region –insula

(p<0.01)– exhibited significantly larger BOLD %

change when the subject was driving and performing

additional tasks simultaneously (Figure 3).

Figure 3: BOLD % change of insula.

BOLD Signal Change during Driving with Addition Task using fMRI

101

4 CONCLUSIONS

The outcomes of this study were in agreement with

the previous studies, with cerebral nerve activation

in the similar regions. More specifically, BOLD

signals were increased in the inferior parietal lobule,

precuneus and inferior frontal gyrus regions

associated with recognition (Andersen, 2011), as

well as the precentral gyrus region associated with

arm and eye movements (Graydon et al., 2004;

Spiers, 2007). These regions are responsible for

processing visual information related to the driving

and auditory information related to the additional

tasks which involve listening to the questions and

providing answers. Furthermore, BOLD signals

were increased in the insula, the region associated

with error monitoring and controlling unnecessary

behaviors (Anderson et al., 1994).

Previous studies that focused on the regions and

the changes in the area of cerebral nerve activation

reported that performing extra tasks while driving –

in comparison with driving – reduces the area of

cerebral nerve activation associated with driving but

increases the area associated with performing extra

tasks (Just et al., 2008; Uchiyama et al., 2012).

With increasing demand to supplement (or

overcome) this, there is an increased activity in the

sub-lobular regions which are associated with error

monitoring and controlling unnecessary behaviors

(Graydon et al., 2004). In this study, BOLD signal

difference in the regions commonly activated under

both conditions was compared. In other words,

instead of observing the change in the area of

activation based on the condition, the intensity of

activity in the same activated region was observed.

The outcomes of this study suggest that when

driving and performing extra task simultaneously –

in comparison with driving – BOLD signal was

greater in the inferior and superior temporal gyri,

which are associated with extra tasks. Furthermore,

BOLD signal was also greater in the insula region

associated with error monitoring and controlling

unnecessary behavior. Nonetheless, the differences

in BOLD signal were not observed in other regions

directly or indirectly associated with driving. These

findings further confirmed the outcomes of previous

studies that have utilized BOLD signal intensity,

which is another important measurement index of

the changes in cerebral nerve activation. However, at

the same time, these findings also raise the need for

additional studies.

In conclusion, comprehensive analysis of the

outcomes from the previous studies – that focused

on the region and the change in the area of cerebral

nerve activation – and this study – which focused on

the change in the size of activation – suggests that

while driving and performing addition tasks

simultaneously, in comparison with driving, both the

area and the size of neural activation increased in the

regions associated with performing addition tasks

and controlling unnecessary behaviors. However,

other regions deeply related to driving (i.e. region

associated with spatial recognition) did not exhibit

change in the size of neural activation in this study,

despite the previous study outcomes that

demonstrated decreased area of neural activation.

Additional studies are required to explain this

deviation, and potential reasons include: the

difference in the sensitivity of the two indices;

differences in the characteristics of neural activation;

or experimental design.

ACKNOWLEDGEMENTS

This work was supported by a Mid-career

Researcher Program Grant through the National

Research Foundation of Korea (NRF), funded by the

Ministry of Education (MOE) (No. 2017R1A2

B2004629). This research was supported by Basic

Science Research Program through the National

Research Foundation of Korea (NRF) funded by the

Ministry of Education (2017R1D1A1B03029585).

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