Institute for Human Neuroscience, Boys Town National Research Hospital, Omaha, NE, USA.
Interdisciplinary Graduate Program in Biomedical Sciences (Neuroscience), University of Nebraska Medical Center, Omaha, NE, USA.
J Physiol. 2021 Dec;599(24):5451-5463. doi: 10.1113/JP282387. Epub 2021 Nov 30.
Fluid intelligence (Gƒ) includes logical reasoning abilities and is an essential component of normative cognition. Despite the broad consensus that parieto-prefrontal connectivity is critical for Gƒ (e.g. the parieto-frontal integration theory of intelligence, P-FIT), the dynamics of such functional connectivity during logical reasoning remains poorly understood. Further, given the known importance of these brain regions for Gƒ, numerous studies have targeted one or both of these areas with non-invasive stimulation with the goal of improving Gƒ, but to date there remains little consensus on the overall stimulation-related effects. To examine this, we applied high-definition direct current anodal stimulation to the left and right dorsolateral prefrontal cortex (DLPFC) of 24 healthy adults for 20 min in three separate sessions (sham, left, and right active). Following stimulation, participants completed a logical reasoning task during magnetoencephalography (MEG). Significant neural responses at the sensor-level were imaged using a beamformer, and peak task-induced activity was subjected to dynamic functional connectivity analyses to evaluate the impact of distinct stimulation montages on network activity. We found that participants responded faster following right DLPFC stimulation vs. sham. Moreover, our neural findings followed a similar trajectory of effects such that left parieto-frontal connectivity decreased following right and left DLPFC stimulation compared to sham, with connectivity following right stimulation being significantly correlated with the faster reaction times. Importantly, our findings are consistent with P-FIT, as well as the neural efficiency hypothesis (NEH) of intelligence. In sum, this study provides evidence for beneficial effects of right DLPFC stimulation on logical reasoning. KEY POINTS: Logical reasoning is an indispensable component of fluid intelligence and involves multispectral oscillatory activity in parietal and frontal regions. Parieto-frontal integration is well characterized in logical reasoning; however, its direct neural quantification and neuromodulation by brain stimulation remain poorly understood. High-definition transcranial direct current stimulation of dorsolateral prefrontal cortex (DLPFC) had modulatory effects on task performance and neural interactions serving logical reasoning, with right stimulation showing beneficial effects. Right DLPFC stimulation led to a decrease in the response time (i.e. better task performance) and left parieto-frontal connectivity with a marginal positive association between behavioural and neural metrics. Other modes of targeted stimulation of DLPFC (e.g. frequency-specific) can be employed in future studies.
流体智力（Gƒ）包括逻辑推理能力，是规范认知的重要组成部分。尽管人们普遍认为顶叶-前额叶连接对于 Gƒ 至关重要（例如，智力的顶叶-前额叶整合理论，P-FIT），但在进行逻辑推理时，这种功能连接的动态仍然知之甚少。此外，鉴于这些大脑区域对 Gƒ 的重要性，许多研究都针对这些区域中的一个或两个区域进行了非侵入性刺激，以提高 Gƒ，但迄今为止，对于整体刺激相关效应仍没有共识。为了研究这一点，我们在三个单独的疗程中（假刺激、左刺激和右刺激）对 24 名健康成年人的左右背外侧前额叶皮层（DLPFC）施加了 20 分钟的高清晰度直流电阳极刺激。刺激后，参与者在磁共振脑磁图（MEG）期间完成了逻辑推理任务。使用波束形成器对传感器水平的显着神经反应进行成像，并对峰值任务诱导的活动进行动态功能连接分析，以评估不同刺激模式对网络活动的影响。我们发现，与假刺激相比，右 DLPFC 刺激后参与者的反应更快。此外，我们的神经发现遵循类似的效应轨迹，与假刺激相比，左右 DLPFC 刺激后左顶叶-前额叶的连接减少，而右刺激后的连接与更快的反应时间显着相关。重要的是，我们的发现与 P-FIT 以及智力的神经效率假说（NEH）一致。总之，这项研究为右 DLPFC 刺激对逻辑推理的有益影响提供了证据。关键点：逻辑推理是流体智力不可或缺的组成部分，涉及顶叶和额叶区域的多谱振荡活动。顶叶-前额叶整合在逻辑推理中得到了很好的描述；然而，其直接神经量化和脑刺激的神经调节仍知之甚少。背外侧前额叶皮层（DLPFC）的高清晰度经颅直流电刺激对逻辑推理的任务表现和神经相互作用具有调节作用，右刺激显示出有益的效果。右 DLPFC 刺激导致反应时间（即更好的任务表现）和左顶叶-前额叶连接减少，行为和神经指标之间存在边际正相关。未来的研究可以采用 DLPFC 的其他靶向刺激模式（例如，频率特异性）。
