TY  - JOUR
AU  - Bjekić, Jovana
AU  - Živanović, Marko
AU  - Paunović, Dunja
AU  - Vulić, Katarina
AU  - Konstantinović, Uroš
AU  - Filipović, Saša
PY  - 2022
UR  - http://rimi.imi.bg.ac.rs/handle/123456789/1230
AB  - Associative memory (AM) is the ability to remember the relationship between previously unrelated items. AM is significantly affected by normal aging and neurodegenerative conditions, thus there is a growing interest in applying non-invasive brain stimulation (NIBS) techniques for AM enhancement. A growing body of studies identifies posterior parietal cortex (PPC) as the most promising cortical target for both transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (tES) to modulate a cortico-hippocampal network that underlines AM. In that sense, theta frequency oscillatory tES protocols, targeted towards the hallmark oscillatory activity within the cortico-hippocampal network, are increasingly coming to prominence. To increase precision and effectiveness, the need for EEG guided individualization of the tES protocols is proposed. Here, we present the study protocol in which two types of personalized oscillatory tES–transcranial alternating current stimulation (tACS) and oscillatory transcranial direct current stimulation (otDCS), both frequency-modulated to the individual theta-band frequency (ITF), are compared to the non-oscillatory transcranial direct current stimulation (tDCS) and to the sham stimulation. The study has cross-over design with four tES conditions (tACS, otDCS, tDCS, sham), and the comprehensive set of neurophysiological (resting state EEG and AM-evoked EEG) and behavioral outcomes, including AM tasks (short-term associative memory, face–word, face–object, object-location), as well as measures of other cognitive functions (cognitive control, verbal fluency, and working memory).
T2  - Brain Sciences
T1  - Personalized Frequency Modulated Transcranial Electrical Stimulation for Associative Memory Enhancement
IS  - 4
SP  - 472
VL  - 12
DO  - 10.3390/brainsci12040472
ER  - 

@article{
author = "Bjekić, Jovana and Živanović, Marko and Paunović, Dunja and Vulić, Katarina and Konstantinović, Uroš and Filipović, Saša",
year = "2022",
abstract = "Associative memory (AM) is the ability to remember the relationship between previously unrelated items. AM is significantly affected by normal aging and neurodegenerative conditions, thus there is a growing interest in applying non-invasive brain stimulation (NIBS) techniques for AM enhancement. A growing body of studies identifies posterior parietal cortex (PPC) as the most promising cortical target for both transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (tES) to modulate a cortico-hippocampal network that underlines AM. In that sense, theta frequency oscillatory tES protocols, targeted towards the hallmark oscillatory activity within the cortico-hippocampal network, are increasingly coming to prominence. To increase precision and effectiveness, the need for EEG guided individualization of the tES protocols is proposed. Here, we present the study protocol in which two types of personalized oscillatory tES–transcranial alternating current stimulation (tACS) and oscillatory transcranial direct current stimulation (otDCS), both frequency-modulated to the individual theta-band frequency (ITF), are compared to the non-oscillatory transcranial direct current stimulation (tDCS) and to the sham stimulation. The study has cross-over design with four tES conditions (tACS, otDCS, tDCS, sham), and the comprehensive set of neurophysiological (resting state EEG and AM-evoked EEG) and behavioral outcomes, including AM tasks (short-term associative memory, face–word, face–object, object-location), as well as measures of other cognitive functions (cognitive control, verbal fluency, and working memory).",
journal = "Brain Sciences",
title = "Personalized Frequency Modulated Transcranial Electrical Stimulation for Associative Memory Enhancement",
number = "4",
pages = "472",
volume = "12",
doi = "10.3390/brainsci12040472"
}

Bjekić, J., Živanović, M., Paunović, D., Vulić, K., Konstantinović, U.,& Filipović, S.. (2022). Personalized Frequency Modulated Transcranial Electrical Stimulation for Associative Memory Enhancement. in Brain Sciences, 12(4), 472.
https://doi.org/10.3390/brainsci12040472

Bjekić J, Živanović M, Paunović D, Vulić K, Konstantinović U, Filipović S. Personalized Frequency Modulated Transcranial Electrical Stimulation for Associative Memory Enhancement. in Brain Sciences. 2022;12(4):472.
doi:10.3390/brainsci12040472 .

Bjekić, Jovana, Živanović, Marko, Paunović, Dunja, Vulić, Katarina, Konstantinović, Uroš, Filipović, Saša, "Personalized Frequency Modulated Transcranial Electrical Stimulation for Associative Memory Enhancement" in Brain Sciences, 12, no. 4 (2022):472,
https://doi.org/10.3390/brainsci12040472 . .

TY  - JOUR
AU  - Živanović, Marko
AU  - Bjekić, Jovana
AU  - Konstantinović, Uroš
AU  - Filipović, Saša
PY  - 2022
UR  - http://rimi.imi.bg.ac.rs/handle/123456789/1254
AB  - Associative memory (AM) is the ability to remember and retrieve multiple items bound together. Previous studies aiming to modulate AM by various transcranial electric stimulation (tES) techniques were inconclusive, although overall suggestive that tES could be a tool for AM enhancement. However, evidence from a direct comparison between different tES techniques is lacking. Here, in a sham-controlled cross-over experiment, we comparatively assessed the effects of three types of tES—anodal tDCS, theta-band transcranial alternating current stimulation (tACS), and theta-oscillatory tDCS (otDCS), delivered over the left posterior parietal cortex, during a short-term digit-color AM task with cued-recall. The effects were tested in 40 healthy young participants while both oscillatory tES were delivered at a previously determined individual theta frequency (4–8 Hz). All three active stimulations facilitated the overall AM performance, and no differences could be detected between them on direct comparison. However, unlike tDCS, the effects of which appeared to stem mainly from the facilitation of low-memory demand trials, both theta-modulated tACS and otDCS primarily promoted AM in high memory demand trials. Comparable yet differential effects of tDCS, theta tACS, and otDCS could be attributed to differences in their presumed modes of action.
PB  - Springer Nature
T2  - Scientific Reports
T1  - Effects of online parietal transcranial electric stimulation on associative memory: a direct comparison between tDCS, theta tACS, and theta-oscillatory tDCS
IS  - 1
SP  - 14091
VL  - 12
DO  - 10.1038/s41598-022-18376-5
ER  - 

@article{
author = "Živanović, Marko and Bjekić, Jovana and Konstantinović, Uroš and Filipović, Saša",
year = "2022",
abstract = "Associative memory (AM) is the ability to remember and retrieve multiple items bound together. Previous studies aiming to modulate AM by various transcranial electric stimulation (tES) techniques were inconclusive, although overall suggestive that tES could be a tool for AM enhancement. However, evidence from a direct comparison between different tES techniques is lacking. Here, in a sham-controlled cross-over experiment, we comparatively assessed the effects of three types of tES—anodal tDCS, theta-band transcranial alternating current stimulation (tACS), and theta-oscillatory tDCS (otDCS), delivered over the left posterior parietal cortex, during a short-term digit-color AM task with cued-recall. The effects were tested in 40 healthy young participants while both oscillatory tES were delivered at a previously determined individual theta frequency (4–8 Hz). All three active stimulations facilitated the overall AM performance, and no differences could be detected between them on direct comparison. However, unlike tDCS, the effects of which appeared to stem mainly from the facilitation of low-memory demand trials, both theta-modulated tACS and otDCS primarily promoted AM in high memory demand trials. Comparable yet differential effects of tDCS, theta tACS, and otDCS could be attributed to differences in their presumed modes of action.",
publisher = "Springer Nature",
journal = "Scientific Reports",
title = "Effects of online parietal transcranial electric stimulation on associative memory: a direct comparison between tDCS, theta tACS, and theta-oscillatory tDCS",
number = "1",
pages = "14091",
volume = "12",
doi = "10.1038/s41598-022-18376-5"
}

Živanović, M., Bjekić, J., Konstantinović, U.,& Filipović, S.. (2022). Effects of online parietal transcranial electric stimulation on associative memory: a direct comparison between tDCS, theta tACS, and theta-oscillatory tDCS. in Scientific Reports
Springer Nature., 12(1), 14091.
https://doi.org/10.1038/s41598-022-18376-5

Živanović M, Bjekić J, Konstantinović U, Filipović S. Effects of online parietal transcranial electric stimulation on associative memory: a direct comparison between tDCS, theta tACS, and theta-oscillatory tDCS. in Scientific Reports. 2022;12(1):14091.
doi:10.1038/s41598-022-18376-5 .

Živanović, Marko, Bjekić, Jovana, Konstantinović, Uroš, Filipović, Saša, "Effects of online parietal transcranial electric stimulation on associative memory: a direct comparison between tDCS, theta tACS, and theta-oscillatory tDCS" in Scientific Reports, 12, no. 1 (2022):14091,
https://doi.org/10.1038/s41598-022-18376-5 . .

TY  - JOUR
AU  - Bjekić, Jovana
AU  - Paunović, Dunja
AU  - Živanović, Marko
AU  - Stanković, Marija
AU  - Griskova-Bulanova, Inga
AU  - Filipović, Saša
PY  - 2022
UR  - http://rimi.imi.bg.ac.rs/handle/123456789/1259
AB  - Non-invasive brain stimulation (NIBS) methods have gained increased interest in research and therapy of associative memory (AM) and its impairments. However, the one-size-fits-all approach yields inconsistent findings, thus putting forward the need for electroencephalography (EEG)-guided personalized frequency-modulated NIBS protocols to increase the focality and the effectiveness of the interventions. Still, extraction of individual frequency, especially in the theta band, turned out to be a challenging task. Here we present an approach to extracting the individual theta-band frequency (ITF) from EEG signals recorded during the AM task. The method showed a 93% success rate, good reliability, and the full range of variability of the extracted ITFs. This paper provides a rationale behind the adopted approach and critically evaluates it in comparison to the alternative methods that have been reported in the literature. Finally, we discuss how it could be used as an input parameter for personalized frequency-modulated NIBS approaches—transcranial alternating current stimulation (tACS) and transcranial oscillatory current stimulation (otDCS) directed at AM neuromodulation.
PB  - Frontiers Media S.A.
T2  - Journal of Personalized Medicine
T1  - Determining the Individual Theta Frequency for Associative Memory Targeted Personalized Transcranial Brain Stimulation
IS  - 9
SP  - 1367
VL  - 12
DO  - 10.3390/jpm12091367
ER  - 

@article{
author = "Bjekić, Jovana and Paunović, Dunja and Živanović, Marko and Stanković, Marija and Griskova-Bulanova, Inga and Filipović, Saša",
year = "2022",
abstract = "Non-invasive brain stimulation (NIBS) methods have gained increased interest in research and therapy of associative memory (AM) and its impairments. However, the one-size-fits-all approach yields inconsistent findings, thus putting forward the need for electroencephalography (EEG)-guided personalized frequency-modulated NIBS protocols to increase the focality and the effectiveness of the interventions. Still, extraction of individual frequency, especially in the theta band, turned out to be a challenging task. Here we present an approach to extracting the individual theta-band frequency (ITF) from EEG signals recorded during the AM task. The method showed a 93% success rate, good reliability, and the full range of variability of the extracted ITFs. This paper provides a rationale behind the adopted approach and critically evaluates it in comparison to the alternative methods that have been reported in the literature. Finally, we discuss how it could be used as an input parameter for personalized frequency-modulated NIBS approaches—transcranial alternating current stimulation (tACS) and transcranial oscillatory current stimulation (otDCS) directed at AM neuromodulation.",
publisher = "Frontiers Media S.A.",
journal = "Journal of Personalized Medicine",
title = "Determining the Individual Theta Frequency for Associative Memory Targeted Personalized Transcranial Brain Stimulation",
number = "9",
pages = "1367",
volume = "12",
doi = "10.3390/jpm12091367"
}

Bjekić, J., Paunović, D., Živanović, M., Stanković, M., Griskova-Bulanova, I.,& Filipović, S.. (2022). Determining the Individual Theta Frequency for Associative Memory Targeted Personalized Transcranial Brain Stimulation. in Journal of Personalized Medicine
Frontiers Media S.A.., 12(9), 1367.
https://doi.org/10.3390/jpm12091367

Bjekić J, Paunović D, Živanović M, Stanković M, Griskova-Bulanova I, Filipović S. Determining the Individual Theta Frequency for Associative Memory Targeted Personalized Transcranial Brain Stimulation. in Journal of Personalized Medicine. 2022;12(9):1367.
doi:10.3390/jpm12091367 .

Bjekić, Jovana, Paunović, Dunja, Živanović, Marko, Stanković, Marija, Griskova-Bulanova, Inga, Filipović, Saša, "Determining the Individual Theta Frequency for Associative Memory Targeted Personalized Transcranial Brain Stimulation" in Journal of Personalized Medicine, 12, no. 9 (2022):1367,
https://doi.org/10.3390/jpm12091367 . .

TY  - JOUR
AU  - Bjekić, Jovana
AU  - Živanović, Marko
AU  - Filipović, Saša
PY  - 2021
UR  - http://rimi.imi.bg.ac.rs/handle/123456789/1266
AB  - Memory enhancement is one of the great challenges in cognitive neuroscience and neurorehabilitation. Among various techniques used for memory enhancement, transcranial direct current stimulation (tDCS) is emerging as an especially promising tool for improvement of memory functions in a non-invasive manner. Here, we present a tDCS protocol that can be applied for memory enhancement in healthy-participant studies as well as in aging and dementia research. The protocol uses weak constant anodal current to stimulate cortical targets within cortico-hippocampal functional network engaged in memory processes. The target electrode is placed either on the posterior parietal cortex (PPC) or the dorsolateral prefrontal cortex (DLPFC), while the return electrode is placed extracranially (i.e., on the contralateral cheek). In addition, we outline a more advanced method of oscillatory tDCS, mimicking a natural brain rhythm to promote hippocampus-dependent memory functions, which can be applied in a personalized and non-personalized manner. We present illustrative results of associative and working memory improvement following single tDCS sessions (20 minutes) in which the described electrode montages were used with current intensities between 1.5 mA and 1.8 mA. Finally, we discuss crucial steps in the protocol and methodological decisions that must be made when designing a tDCS study on memory.
T2  - Journal of Visualized Experiments
T1  - Transcranial direct current stimulation (Tdcs) for memory enhancement
IS  - 175
SP  - e62681
VL  - 2021
DO  - 10.3791/62681
ER  - 

@article{
author = "Bjekić, Jovana and Živanović, Marko and Filipović, Saša",
year = "2021",
abstract = "Memory enhancement is one of the great challenges in cognitive neuroscience and neurorehabilitation. Among various techniques used for memory enhancement, transcranial direct current stimulation (tDCS) is emerging as an especially promising tool for improvement of memory functions in a non-invasive manner. Here, we present a tDCS protocol that can be applied for memory enhancement in healthy-participant studies as well as in aging and dementia research. The protocol uses weak constant anodal current to stimulate cortical targets within cortico-hippocampal functional network engaged in memory processes. The target electrode is placed either on the posterior parietal cortex (PPC) or the dorsolateral prefrontal cortex (DLPFC), while the return electrode is placed extracranially (i.e., on the contralateral cheek). In addition, we outline a more advanced method of oscillatory tDCS, mimicking a natural brain rhythm to promote hippocampus-dependent memory functions, which can be applied in a personalized and non-personalized manner. We present illustrative results of associative and working memory improvement following single tDCS sessions (20 minutes) in which the described electrode montages were used with current intensities between 1.5 mA and 1.8 mA. Finally, we discuss crucial steps in the protocol and methodological decisions that must be made when designing a tDCS study on memory.",
journal = "Journal of Visualized Experiments",
title = "Transcranial direct current stimulation (Tdcs) for memory enhancement",
number = "175",
pages = "e62681",
volume = "2021",
doi = "10.3791/62681"
}

Bjekić, J., Živanović, M.,& Filipović, S.. (2021). Transcranial direct current stimulation (Tdcs) for memory enhancement. in Journal of Visualized Experiments, 2021(175), e62681.
https://doi.org/10.3791/62681

Bjekić J, Živanović M, Filipović S. Transcranial direct current stimulation (Tdcs) for memory enhancement. in Journal of Visualized Experiments. 2021;2021(175):e62681.
doi:10.3791/62681 .

Bjekić, Jovana, Živanović, Marko, Filipović, Saša, "Transcranial direct current stimulation (Tdcs) for memory enhancement" in Journal of Visualized Experiments, 2021, no. 175 (2021):e62681,
https://doi.org/10.3791/62681 . .