The Application of Multichannel Neuro-electrostimulation for

Working Memory and Attention Improvement of Young Subjects

Anna Petrenko

and Vladimir Kublanov

Ural Federal University, Mira 19, 620002, Yekaterinburg, Russian Federation

Keywords: Attention, Neuro-electrostimulation, Neuroplasticity, N-back, Working Memory.

Abstract: The paper discusses the possibilities of using multichannel neuro-electrostimulation method to improve the

characteristics of attention and working memory of young subjects. It was shown that the results of the test

for assessment of working memory and attention in the experimental group with the use of neuro-

electrostimulation was higher than those in the control and placebo groups. In addition, during the processing

of the functional studies data, such heart rate variability parameters were obtained, the dynamics of which

reflects the positive effect of neuro-electrostimulation. It was found that the effect of neuro-electrostimulation

affects the formation of increased activity of the sympathetic nervous system of the body due to the

intensification of the action of energy processes.

1 INTRODUCTION

In an intensively developing information society, the

need for improving cognitive functions is steadily

growing. In recent years, the active attention of many

researchers has been drawn to the search for new

methods to improve brain function. Improving

cognitive skills is a multifaceted concept involving

the study of the fundamental mechanisms of the brain

functioning at different levels of its organization

(Dresler et al., 2019).

Now there is an active study of factors and

conditions to provide more effective methods for

improving cognitive skills. One of the main

conditions for ensuring the ability to learn is the

active functioning of neuroplasticity processes

(Maslach & Leiter, 2016).

Neuroplasticity is a set of multilevel processes of

continuous morphological and functional

reorganization of the brain, thus ensuring adaptation

to changing external and internal conditions

(Schverer et al., 2018). One of the hypotheses is the

assumption that neuro-electrostimulation allows to

reorganize neural networks by modulating their

connections and is able to modulate higher cortical

functions - to facilitate learning, recognition of visual

https://orcid.org/0000-0001-5906-5755

https://orcid.org/0000-0001-6584-4544

images, improve memory and decision-making, and

can also be used for neurocognitive rehabilitation

(DARPA, 2016). Thus, one of the promising methods

for improving cognitive skills can be the use of neuro-

electrostimulation methods.

2 MATERIALS AND METHODS

The study was approved by the local ethics committee

at the Ural State Medical University in accordance

with the protocol number 8 on October 16, 2015.

Practically healthy subjects participated in the

studies.

In previous paper (Kublanov & Petrenko, 2018)

we described in more detail the research

methodology.

2.1 Estimation Method of Attention

and Working Memory

N-back test is selected to estimate of working

memory and attention functions. Step of

memorization is N=2. Subjects work with a sequence

of position and audio stimuli presented one in each

time interval and must give an answer if the current

Petrenko, A. and Kublanov, V.

The Application of Multichannel Neuro-electrostimulation for Working Memory and Attention Improvement of Young Subjects.

DOI: 10.5220/0010395302550260

In Proceedings of the 14th International Joint Conference on Biomedical Engineering Systems and Technologies (BIOSTEC 2021) - Volume 1: BIODEVICES, pages 255-260

ISBN: 978-989-758-490-9

255

stimulus coincides with the element represented by 2

intervals back (dual 2-back test).

The quality of the test was assessed according to

the following parameters: mean response time of

position and audio stimuli, score of position stimuli,

score of audio stimuli, total score.

2.2 Neuro-electrostimulation Method

The ‘SYMPATHOCOR-01’ device is selected as the

multichannel neuro-electrostimulation method.

Device generates spatially distributed field of current

pulses (Danilov et al., 2015; Kublanov et al., 2014)

and it is approved for use in medical institutions of

the Russian Federation and has a state certificate of

the Federal Service on Surveillance in Healthcare and

Social Development № FSR 2007/00757 от

27.09.2007. Applying of the device does not cause

side effects ( Kublanov et al., 2010).

For the current study parameters field of the

current pulses were as follows: the amplitude of the

partial current pulses is 4mA, the pulse duration of the

partial current is 50 microseconds, the frequency of

the partial current pulses is 80 Hz.

The advantage of using this method is the

application of a non-invasive multielectrode

neuroelectrostimulation. The ‘SYMPATHOCOR-01’

device is a mobile and portable device, has the ability

to individually select the parameters of stimulation,

as well as its use is possible simultaneously with other

functional and psychometric tests.

2.3 Sequence of Research Stages

At the first stage of the study, 65 subjects aged 20 to

25 years took part, randomly divided into the

experimental (33 persons), control (10) and placebo

(22) groups. Subjects initially performed the dual 2-

back test in order to determine the baseline values for

attention and working memory parameters.

The sequence diagram of the first stage of the

study is shown in Table 1.

Table 1: Sequence diagram.

№ step Name of step

Duration, min.

Background 5

dual 2-back test 5

Rest 5

dual 2-back test 5

Background 5

At the second stage of the study subjects of the

experimental group performed simultaneously with

the corrective action of the neuro-electrostimulation

device during 5 day. Subjects of the placebo group

performed dual 2-back test simultaneously with the

placebo stimulation during 5 day. In placebo

stimulation, a sequence of current pulses is formed by

one anode and one cathode, and the target of the

implications is the neck areas in which the presence

of the sympathetic nervous system fibers is minimal.

Subjects of the control group performed a stress

test without corrective action during 5 day.

Table 2: Sequence diagram.

Experimental

group

Placebo

group

Control

group

Duration,

min.

Background 5

neuro-

electrostimula

tion +

dual 2-back

test

placebo

stimulation+

dual 2-back

test

dual 2-

back test

Rest 5

neuro-

electrostimula

tion +

dual 2-back

test

placebo

stimulation+

dual 2-back

test

Background 5

For experimental and placebo groups ECG signal

was registered at the 1

and 5

days. The ECG

registration was carried out using

electroencephalograph-recorder «Encephalan -

EEGR-19/26».

«STATISTICA 12.0» software applications were

used for statistical analysis of the obtained data

during study.

3 RESULTS

3.1 Results of the Test Parameters

The variance analysis (ANOVA) of test parameters

was carried out to assess difference between

experimental, control and placebo groups.

During the ANOVA significant changes were

obtained for the mean response time position and total

score variables. The values obtained are reliable at the

level of p≤0,05.

The results of the ANOVA for mean response

time position and total score with the marked ranges

NDNSNT 2021 - Special Session on Non-invasive Diagnosis and Neuro-stimulation in Neurorehabilitation Tasks

256

of standard deviation in the experimental, placebo

and control groups are presented in Figures 1-2.

Figure 1: Changes of mean response time position for each

groups.

Figure 2: Changes of total score for each groups.

For the experimental group, the test was re-

evaluated after 2 months without the use of neuro-

electrostimulation. The results are presented in

Figures 3-4.

Figure 3: Repeated ANOVA results of mean response time

in the experimental group.

Figure 4: Repeated ANOVA results of Total score in the

experimental group.

According to the primary assessment of the

parameters of the dual 2-back test, the average values

of total score in the three groups was (41 ± 1.9)%.

After the first procedure of neuro -

electrostimulation, the average values of total score in

the experimental group was (58.5 ± 1.9)%, in the

control group - (53.3 ± 3.1)%, in the placebo group -

(52.7 ± 2.1)%. At the same time, there is the greatest

increase in total score values - in all three groups.

A significant difference between the three groups

is observed as early as 3

day of the neuro-

electrostimulation procedure. The average values of

total score in the experimental group after the 3

neuro-electrostimulation was (69.6 ± 1.8)%, in the

control group - (63 ± 5.6)%, in the placebo group -

(63 ± 2.3)% .

Also, after data processing the, significant

changes were obtained in the mean response time of

position stimuli.

According to the initial assessment, the mean

response time of position stimuli in the three groups

was (1.39 ± 0.06) sec.

On the 3

day, the mean response time of position

stimuli in the experimental group was (1.19 ± 0.03)

sec., in the placebo and control groups - (1.24 ± 0.05)

sec. and (1.26 ± 0.06) sec. respectively.

By re-evaluating the test parameters in the

experimental group after 2 months, the results are

preserved both in the mean response time total score.

3.2 Results of HRV Analysis

Heart rate variability (HRV) data were obtained from

the recorded ECG signal. For data analysis, the 64

parameters of HRV were obtained using in-house

software in Python (V. Kublanov & Dolganov, 2019).

Further, artifacts and outliers were excluded and

The Application of Multichannel Neuro-electrostimulation for Working Memory and Attention Improvement of Young Subjects

257

calculated the mean values and the corresponding

standard deviations for each group.

The ANOVA for the HRV parameters was carried

out during the 1

and 5

procedures of neuro-

electrostimulation and placebo stimulation in the

experimental and placebo groups to assess functional

changes.

Significant changes were obtained at the level of

p≤0.05 in the following variables: Stress index or

index of regulatory systems tension (SI), index of

autonomic balance (IAB), autonomic rhythm index

(ARI), indicator of the adequacy of regulation

processes (IARP). The obtained data are presented in

Table 3.

Table 3: Values of HRV parameters for the experimental

and control groups on 1

and 5

days.

Experimental

group

Placebo

group

day 1 5 1 5

mean 150,63 156,96 129,92 114,06

std 7,4 7,45 13,7 13,28

IAB

mean 215,43 224,22 192,41 173,32

std 9,37 9,43 17,34 16,8

ARI

mean 7,35 7,53 6,62 6,29

std 0,23 0,23 0,42 0,41

IARP

mean 51,58 52,76 48,58 44,69

std 1,39 1,4 2,57 2,49

The results of analysis of variance are shown in

Figures 5-7.

Figure 5: ANOVA results of ARI at the first and fifth days

in the experimental and placebo groups.

Figure 6: ANOVA results of IARP at the first and fifth days

in the experimental and placebo groups.

Figure 7: ANOVA results of IAB at the first and fifth days

in the experimental and placebo groups.

Figure 8: ANOVA results of SI at the first and fifth days in

the experimental and placebo groups.

Stress index (SI), index of autonomic balance

(IAB), autonomic rhythm index (ARI), indicator of

the adequacy of regulation processes (IARP) reflect

the degree of adaptation of the cardiovascular system

to various factors (Baevsky & Ivanov, 2001).

Autonomic rhythm index (ARI) reflects the

balance of regulation of the cardiovascular system by

the sympathetic and parasympathetic parts of the

autonomic nervous system. During the 5

procedure

of neuro-electrostimulation parameter ARI in the

NDNSNT 2021 - Special Session on Non-invasive Diagnosis and Neuro-stimulation in Neurorehabilitation Tasks

258

experimental group was higher on 20% than in the

placebo group. An increase of the ARI value indicates

an increased activity of the sympathetic nervous

system in the subjects of the experimental group.

The index of autonomic balance (IAB) shows the

ratio of the effect on the cardiovascular system of the

sympathetic and parasympathetic systems. For

subjects of the experimental group, there is an

increase in this indicator at the 5

procedure of neuro-

electrostimulation compared with the placebo group.

This indicates an increase in the role of the

sympathetic nervous system. For subjects in the

placebo group, the IAB score is lower; therefore, the

parasympathetic nervous system has a predominant

effect.

The indicator of the adequacy of regulation

processes (IARP) allows one to determine the effect

on the sinus node of the sympathetic section and is the

most stable indicator. For subjects, this indicator

during the 5

procedure of neuro-electrostimulation

was 52.76 ± 1.4, which is higher than those in the

placebo group - 44.69 ± 2.49. The obtained data

indicate an increase in the sympathetic part of the

nervous system through the action of neuro-

electrostimulation; the influence of the sinus node on

heart rate becomes more pronounced.

The stress index (SI) indicates the degree of

influence of the nervous system on the work of the

heart. For the subjects of the experimental group,

there is an increase of this indicator relative to the

placebo group, which indicates the formation in the

body of an increased activity of the sympathetic

division and an increase in the degree of

centralization of heart rate control. This may indicate

the effect of the influence of neuro-electrostimulation

on the regulation of sympathetic nervous structures,

which reflects the activation of ergotropic

mechanisms of regulation and an increase in the

intensity of energy processes.

4 DISCUSSION

The results of the study showed that the use of neuro-

electrostimulation of the peripheral nervous system in

conjunction with a dual 2-back test improves working

memory, reaction time and attention parameters. It

was shown that performance of three neuro-

electrostimulation procedures is enough to see

significant intergroup differences in the parameters of

the performed N-back test.

The advantage of the proposed technique for

increasing the level of concentration and attention is

the use of a non-invasive multielectrode neuro-

electrostimulation system implemented in the

‘SYMPATHOCOR-01’ device. A possible

mechanism of action is the activation of peripheral

nerves, which in turn facilitate and strengthen neural

connections in the brain. The activation of peripheral

nerves occurs using neuro-electrical stimulation of

the cervical ganglia of the sympathetic nervous

system and the corresponding pathways of the nerve

formations.

Furthermore, while processing the data of

functional studies, HRV parameters were obtained,

the dynamics of which reflects the positive effect of

neuro-electrostimulation. It was found that the effect

of neuro-electrostimulation affects the formation of

increased activity of the sympathetic nervous system

of the body due to the intensification of the action of

energy processes.

To increase the reliability of intergroup

differences in other functional parameters of HRV, it

is necessary to increase the number of samples in each

group.

5 CONCLUSION

During the study, a technique was developed for

increasing the level of attention and working memory

using neuro-electrostimulation. The advantage of this

method is the use of a mobile and portable unit of

non-invasive neuro-electrostimulation with the

possibility of individual selection of neuro-

electrostimulation parameters. The technique allows

you to combine neuro-electrostimulation with other

loads (for example, with psychometric tests), as well

as monitor the functional state of a person using ECG

registration.

ACKNOWLEDGEMENTS

The reported study was funded by RFBR according

to the research project № 18-29-02052.

REFERENCES

Baevsky, R. M., & Ivanov, G. G. (2001). Analysis of heart

rate variability using various electrocardiographic

systems: A guidelines. 24, 65–68.

Danilov, Y. P., Kublanov, V. S., Retjunskij, K. J., Petrenko,

T. S., & Babich, M. V. (2015). Non-invasive multi-

channel neuro-stimulators in treatment of the nervous

system disorders. BIODEVICES 2015 - 8th

International Conference on Biomedical Electronics

The Application of Multichannel Neuro-electrostimulation for Working Memory and Attention Improvement of Young Subjects

259

and Devices, Proceedings; Part of 8th International

Joint Conference on Biomedical Engineering Systems

and Technologies, BIOSTEC 2015, 88–94.

https://doi.org/10.5220/0005200000880094.

DARPA. (2016). Targeted Neuroplasticity Training (TNT).

Biological Technologies Office, 36p.

Dresler, M., Sandberg, A., Bublitz, C., Ohla, K., Trenado,

C., Mroczko-Wąsowicz, A., Kühn, S., & Repantis, D.

(2019). Hacking the Brain: Dimensions of Cognitive

Enhancement. ACS Chemical Neuroscience, 10(3),

1137–1148.

https://doi.org/10.1021/acschemneuro.8b00571

Jaeggi, S. M., Studer-Luethi, B., Buschkuehl, M., Su, Y.-

F., Jonides, J., & Perrig, W. J. (2010). The relationship

between n-back performance and matrix reasoning—

Implications for training and transfer. Intelligence,

38(6), 625–635.

https://doi.org/10.1016/j.intell.2010.09.001.

Kublanov, V., & Dolganov, A. (2019). Development of a

decision support system for neuro-electrostimulation:

Diagnosing disorders of the cardiovascular system and

evaluation of the treatment efficiency. Applied Soft

Computing, 77, 329–343.

https://doi.org/10.1016/j.asoc.2019.01.032.

Kublanov, V. S., Chernykh, O. A., Purtov, K. S., & Babich,

M. V. (2014). The hardware-software system for study

of microwave radiation biological effects. 2014 24th

International Crimean Conference Microwave

Telecommunication Technology, 1038–1039.

https://doi.org/10.1109/CRMICO.2014.6959749.

Kublanov, V. S., Petrenko A. A. (2018). On the possibilities

of neuro-electrostimulation for increasing learning

parameters. 2018 11th International Joint Conference

on Biomedical Engineering Systems and Technologies,

338-344. https://doi.org/10.5220/0006592503380344.

Kublanov, V. S., Shmirev, V. I., & Shershever, A. S.

(2010). About innovative possibilities of the device

SYMPATOCOR in management of functional disorders

of autonomic and central nervous system in neurology.

4, 60–64.

Maslach, C., & Leiter, M. P. (2016). Burnout. In Stress:

Concepts, Cognition, Emotion, and Behavior (pp. 351–

357). Elsevier. https://doi.org/10.1016/B978-0-12-

800951-2.00044-3.

Pelegrina, S., Lechuga, M. T., García-Madruga, J. A.,

Elosúa, M. R., Macizo, P., Carreiras, M., Fuentes, L. J.,

& Bajo, M. T. (2015). Normative data on the n-back

task for children and young adolescents. Frontiers in

Psychology, 6, 1544.

https://doi.org/10.3389/fpsyg.2015.01544.

Schverer, M., Lanfumey, L., Baulieu, E.-E., Froger, N., &

Villey, I. (2018). Neurosteroids: Non-genomic

pathways in neuroplasticity and involvement in

neurological diseases. Pharmacology & Therapeutics,

191, 190–206.

https://doi.org/10.1016/j.pharmthera.2018.06.011.

NDNSNT 2021 - Special Session on Non-invasive Diagnosis and Neuro-stimulation in Neurorehabilitation Tasks

260