Department of Education, Psychology and Communication, University of Bari Aldo Moro, Bari, Italy.
Center for Neurodegenerative Diseases and the Aging Brain, University of Bari Aldo Moro at Pia Fondazione "Cardinale G. Panico", Tricase, Lecce, Italy; Department of Translational Biomedicine and Neurosciences (DiBraiN), University of Bari Aldo Moro, Bari, Italy.
Behav Brain Res. 2024 Jan 5;456:114703. doi: 10.1016/j.bbr.2023.114703. Epub 2023 Oct 6.
Gamma-band (> 30 Hz) brain oscillations (γ) play a crucial role in memory and long-term potentiation, and their disruptions have been consistently documented in patients with Alzheimer's Disease (AD). Gamma-band oscillation entrainment through 60 Hz transcranial alternating stimulation (tACS) and 40 Hz tACS/sensory stimulation has been shown to enhance memory performance in healthy adults and patients with AD, respectively. However, the impact of gamma auditory stimulation on healthy adults' memory remains uncertain. In this balanced crossover study, 36 healthy subjects (27 Females) underwent three auditory stimulation conditions: no auditory stimulation (NO_AS), 40 Hz, and 60 Hz. Long-term verbal memory (LTM) and verbal working memory (WM) were assessed using, respectively, the Ray Auditory Verbal Test (RAVLT) and Digit Span Backward test (DS-B). We hypothesized that 60 Hz would improve LTM (as compared to NO_AS), but not WM; no specific effects were hypothesized for 40 Hz. We found that gamma-band auditory stimulation (40 Hz and 60 Hz) did not significantly affect RAVLT recall or WM. However, 60 Hz stimulation reduced RAVLT immediate recall intrusion; this outcome negatively correlated with DS-B performance, suggesting a positive impact of 60 Hz on executive functions. In summary, gamma-band auditory stimulation did not enhance memory in healthy adults, but 60 Hz stimulation potentially benefits executive functions. Further investigation is needed to understand gamma oscillation's role in cognitive processes for both healthy and clinical populations.
伽马波段（>30Hz）脑振荡（γ）在记忆和长期增强中起着至关重要的作用，其在阿尔茨海默病（AD）患者中的破坏一直被记录在案。通过 60Hz 经颅交替刺激（tACS）和 40Hz tACS/感觉刺激进行伽马波段振荡调制，已分别显示出在健康成年人和 AD 患者中增强记忆性能的作用。然而，伽马听觉刺激对健康成年人记忆的影响仍不确定。在这项平衡的交叉研究中，36 名健康受试者（27 名女性）接受了三种听觉刺激条件：无听觉刺激（NO_AS）、40Hz 和 60Hz。使用 Ray 听觉言语测试（RAVLT）和数字跨度倒背测试（DS-B）分别评估长期言语记忆（LTM）和言语工作记忆（WM）。我们假设 60Hz 将改善 LTM（与 NO_AS 相比），但不会改善 WM；对于 40Hz 没有具体的假设。我们发现，伽马波段听觉刺激（40Hz 和 60Hz）并未显著影响 RAVLT 回忆或 WM。然而，60Hz 刺激减少了 RAVLT 即时回忆的侵入；这一结果与 DS-B 表现呈负相关，表明 60Hz 对执行功能有积极影响。总之，伽马波段听觉刺激并未增强健康成年人的记忆力，但 60Hz 刺激可能有益于执行功能。需要进一步研究以了解伽马振荡在健康人群和临床人群认知过程中的作用。
