Dorsolateral Prefrontal Korteksin Modüle Edilmiş Anodal Akım İle Uyarımının Çalışma Belleği Üzerine Etkisinin İncelenmesi: Ön çalışma

Abstract

Amaçlar: Çalışma belleğinin iki bileşeni vardır: geçici depolama ve bilişsel davranış için gerekli bilgilerin merkezi yürütücü sistem aracılığıyla işlenmesi. Bu çalışma, dorsolateral prefrontal kortekse uygulanan modüle edilmiş anodal transkraniyal doğru akım uyarımının (mtDCS) çalışma belleği üzerindeki etkilerini araştırmayı amaçlamıştır. Yöntem: Nörolojik veya psikiyatrik ilaç kullanımı ve tanısı olmayan 12 gönüllü bu çalışmaya katılmıştır. Çalışma belleği performansını ölçmek için, uyarım sırasında ünsüz harflerden oluşan 3-geri bellek testinin görsel versiyonu uygulanmıştır. Değerlendirmenin başında, öğrenmeyi etkisini ortadan kaldırmak amacıyla katılımcılara 20 dakikalık deneme seti uygulanmıştır. Katılımcılar başarı düzeyinde %50’ye ulaştıklarında, dört set uyarım uygulanmıştır. Uyarım setlerinin toplam süresi 10 dakikadır. Uyarım setleri şu koşulları içermektedir: modüle edilmiş akım (11 Hz ve 22 Hz) 1.70 miliamper (mA) offset ve 0.35 mA tepe-tepe akım, sabit akım (DC) koşulunda 2 mA offset ve yalancı (sham) uyarım. 3-geri bellek görevleri sırasında katılımcıların tepki süreleri ve toplam doğru cevapları kaydedilmiştir. Bulgular: 3-geri testinden alınan doğru yanıt ortalamları uyarım koşulları arasında farklılık göstermektedir (χ²(3) = 9.00, p = .029). Sol DLPFC uyarımı, mtDCS ve tDCS koşulları arasındaki ortalama doğru yanıt sayılarında anlamlı bir fark ortaya koymuştur; ancak post-hoc analiz sonucunda bu fark sham koşulla karşılaştırıldığında anlamlı bulunmamıştır. 11 Hz ve 22 Hz mtDCS koşullarında ortalama doğru yanıt sayısı, DC stimülasyona kıyasla anlamlı derecede daha düşük bulunmuştur (Z = -2.56, p <0.017); özellikle 11 Hz mtDCS koşulunun etkisi daha belirgindir. Sonuç: Alfa bandındaki 11 Hz uyarımı, çalışma belleği üzerinde baskılayıcı bir etki göstermiş olabilir. Gelecek çalışmalarda örneklem sayısı artırılarak farklı frekanslardaki uyarım etkileri incelenmelidir.

Keywords

• working memory
• tDCS
• mtDCS
• neuromodulation

Effect of Modulated Anodal Stimulation over the Dorsolateral Prefrontal Cortex on Working Memory: A Preliminary Study

Abstract

Objectives: Working memory has two components: temporary storage and manipulation of the informa tion necessary for cognitive behavior through the central executive system. This study aimed to investigate the effects of modulated anodal transcranial direct current stimulation (mtDCS) of the dorsolateral prefrontal cortex on working memory. Materials and Methods: Twelve volunteers without neurological or psychiatric disorders and without drug use participated. Working memory performance was assessed with a visual 3back task using consonant letters during stimulation. A 20minute training session was conducted to facilitate learning, and participants who achieved an accuracy rate of 50% or higher proceeded to the main experiment. Four stimulation conditions were applied, each lasting 10 minutes: mtDCS11 Hz and mtDCS22 Hz (1.70 mA offset, 0.35 mA peaktopeak), direct current (DC) (2 mA), and sham. Reaction times and total correct responses were recorded. Results: Statistical analysis of the left dorsolateral prefrontal cortex (DLPFC) stimulation revealed a significant difference in the mean numbers of correct responses among the mtDCS and transcranial direct current stimulation (tDCS) conditions, but not compared with sham. The mean number of correct responses under mtDCS11Hz and mtDCS22Hz was significantly lower than under DC stimulation; however the performance decrement under 11 Hz mtDCS was the most pronounced among the active conditions. Conclusion: mtDCS11Hz and mtDCS22Hz negated the subtle facilitation of tDCS might have provided.

Keywords

• Working memory
• Transcranial direct current stimulation
• Electric stimulation therapy

References

1. 1. Lucas I, Urieta P, Balada F, Blanco E, Aluja A. Differences in prefrontal cortex activity based on difficulty in a working memory task using near-infrared spectroscopy. Behav Brain Res 2020; 392: 112722.
2. 2. Yamada Y, Sumiyoshi T. Neurobiological mechanisms of transcranial direct current stimulation for psychiatric disorders; neurophysiological, chemical, and anatomical considerations. Front Hum Neurosci 2021; 15: 631838.
3. 3. Fregni F, Boggio PS, Nitsche M, Bermpohl F, Antal A, Feredoes E, et al. Anodal transcranial direct current stimulation of the prefrontal cortex enhances working memory. Exp Brain Res 2005; 166: 23-30.
4. 4. Teo F, Hoy KE, Daskalakis ZJ, Fitzgerald PB. Investigating the role of current strength in tDCS modulation of working memory performance in healthy controls. Front Psychiatry 2011; 2: 45.
5. 5. Narmashiri A, Akbari F. The effects of transcranial direct current stimulation tDCS on the cognitive functions: A systematic review and meta-analysis. Neuropsychol Rev 2025; 35(1): 126-52.
6. 6. Wischnewski M, Alekseichuk I, Opitz A. Neurocognitive, physiological, and biophysical effects of transcranial alternating current stimulation. Trends Cogn Sci 2023; 27(2): 189-205.
7. 7. Gansel KS. Neural synchrony in cortical networks: mechanisms and implications for neural information processing and coding. Front Integr Neurosci 2022; 16: 900715.
8. 8. van Ede F. Mnemonic and attentional roles for states of attenuated alpha oscillations in perceptual working memory: a review. Eur J Neurosci 2018; 48(7): 2509-15.

9. 9. Pavlov YG, Kotchoubey B. Oscillatory brain activity and maintenance of verbal and visual working memory: A systematic review. Psychophysiol 2022; 59(5): e13735.
10. 10. Bencze D, Marián M, Sz?ll?si Á, Simor P, Racsmány M. Increase in slow frequency and decrease in alpha and beta power during post-learning rest predict long- term memory success. Cortex 2025; 183: 167-82.
11. 11. Zhozhikashvili N, Zakharov I, Ismatullina V, Feklicheva I, Malykh S, Arsalidou M. Parietal alpha oscillations: Cognitive load and mental toughness. Brain Sci 2022; 12(9): 1135.
12. 12. Deiber MP, Hasler R, Colin J, Dayer A, Aubry JM, Baggio S, et al. Linking alpha oscillations, attention, and inhibitory control in adult ADHD with EEG neurofeedback. NeuroImage Clin 2020; 25: 102145.
13. 13. Wianda E, Ross B. The roles of alpha oscillation in working memory retention. Brain Behav 2019; 9(4): e01263.
14. 14. Dong G, Wang Y, Chen X. Anodal occipital tDCS enhances spontaneous alpha activity. Neurosci Lett 2020; 721: 134796.
15. 15. Marián M, Sz?ll?si Á, Racsmány M. Anodal transcranial direct current stimulation of the right dorsolateral prefrontal cortex impairs long-term retention of reencountered memories. Cortex 2018; 108: 80-91.
16. 16. Chen X, Ma R, Zhang W, Zeng GQ, Wu Q, Yimiti A, et al. Alpha oscillatory activity is causally linked to working memory retention. PLoS Biol 2023; 21(2): e3001999.
17. 17. Al-Tawarah NM, Kaptan Z, Abu-Harirah HA, Nofal M, Almajali B, Jarrar S, et al. Effectiveness of anodal otDCS following with anodal tDCS rather than tDCS alone for increasing of relative power of intrinsic matched EEG bands in rat brains. Brain Sci 2022; 13(1): 72.
18. 18. Shalchy MA, Pergher V, Pahor A, Van Hulle MM, Seitz AR. N-back related ERPs depend on stimulus type, task structure, pre-processing, and lab factors. Front Hum Neurosci 2020; 14: 549966.
19. 19. Jones AP, Bryant NB, Robert BM, Mullins TS, Trumbo MC, Ketz NA, Clark VP. Closed-loop tACS delivered during slow-wave sleep reduces retroactive interference on a paired-associates learning task. Brain Sci 2023; 133: 468.
20. 20. Nitsche MA, Paulus W. Sustained excitability elevations induced by transcranial DC motor cortex stimulation in humans. Neurology 2001; 5710: 1899-901.
21. 21. Takahashi A, Iuchi S, Sasaki T, Hashimoto Y, Ishizaka R, Minami K, et al. Working memory load increases movement-related alpha and beta desynchronization. Neuropsychologia 2024; 205: 109030.
22. 22. Ke Y, Jiang T, Liu S, Cao Y, Jiao X, Jiang J, et al. Cross-task consistency of electroencephalography-based mental workload indicators: comparisons between power spectral density and task-irrelevant auditory event-related potentials. Front Neurosci 2021; 15: 703139.
23. 23. Jaquess KJ, Lo LC, Oh H, Lu C, Ginsberg A, Tan YY, et al. Changes in mental workload and motor performance throughout multiple practice sessions under various levels of task difficulty. Neurosci 2018; 393: 305-18.
24. 24. Jensen O. Distractor inhibition by alpha oscillations is controlled by an indirect mechanism governed by goal-relevant information. Commun Psychol 2024; 21: 36.
25. 25. Nissim NR, McAfee DC, Edwards S, Prato A, Lin JX, Lu Z, et al. Efficacy of transcranial alternating current stimulation in the enhancement of working memory performance in healthy adults: a systematic meta-analysis. Neuromodulation 2023; 264: 728-37.
26. 26. Vergallito A, Feroldi S, Pisoni A, Romero Lauro LJ. Inter-individual variability in tDCS effects: a narrative review on the contribution of stable, variable, and contextual factors. Brain Sci 2022; 125: 522.
27. 27. Erdoğan ET, Küçük Z, Eskikurt G, Kurt A, Ermutlu N, Karamürsel S. Single session anodal transcranial direct current stimulation on different cortical areas. J Psychophysiol 2023; 37(2): 101-9.
28. 28. Kuo HI, Bikson M, Datta A, Minhas P, Paulus W, Kuo MF, et al. Comparing cortical plasticity induced by conventional and high-definition 4×1 ring tDCS: a neurophysiological study. Brain Stimul 2013; 6(4): 644-8.
29. 29. Nakamura-Palacios EM, Falçoni Júnior AT, Anders QS, de Paula LDSP, Zottele MZ, Ronchete CF, et al. Would frontal midline theta indicate cognitive changes induced by non-invasive brain stimulation? A mini review. Front Hum Neurosci 2023; 17: 1116890.