School of Psychology, The University of Queensland, St Lucia, Australia.
School of Psychology, The University of Queensland, St Lucia, Australia.
Neuropsychologia. 2020 Apr;141:107433. doi: 10.1016/j.neuropsychologia.2020.107433. Epub 2020 Mar 14.
Applying a weak electrical current to the cortex has the potential to modulate neural functioning and behaviour. The most common stimulation technique, transcranial direct current stimulation (tDCS), has been used for causal investigations of brain and cognitive functioning, and to treat psychiatric conditions such as depression. However, the efficacy of tDCS in modulating behaviour varies across individuals. Moreover, despite being associated with different neural effects, the two polarities of electrical stimulation - anodal and cathodal - can result in similar behavioural outcomes. Here we employed a previously replicated behavioural paradigm that has been associated with polarity non-specific disruption of training effects in a simple decision-making task. We then used the linear ballistic accumulator model to quantify latent components of the decision-making task. In addition, magnetic resonance imaging measures were acquired prior to tDCS sessions to quantify cortical morphology and local neurochemical concentrations. Both anodal and cathodal stimulation disrupted learning-related task improvement relative to sham (placebo) stimulation, but the two polarities of stimulation had distinct effects on latent task components. Whereas anodal stimulation tended to affect decision thresholds for the behavioural task, cathodal stimulation altered evidence accumulation rates. Moreover, performance variability with anodal stimulation was related to cortical thickness of the inferior frontal gyrus, whereas performance variability with cathodal stimulation was related to cortical thickness in the inferior precentral sulcus, as well as to prefrontal neurochemical excitability. Our findings demonstrate that both cortical morphology and local neurochemical balance are important determinants of individual differences in behavioural responses to electrical brain stimulation.
将微弱电流施加于大脑皮层可能会调节神经功能和行为。最常见的刺激技术，经颅直流电刺激（tDCS），已被用于对大脑和认知功能的因果关系研究，并用于治疗抑郁症等精神疾病。然而，tDCS 调节行为的效果在个体之间存在差异。此外，尽管与不同的神经效应相关联，但两种极性的电刺激 - 阳极和阴极 - 可以导致相似的行为结果。在这里，我们采用了以前复制的行为范式，该范式与在简单决策任务中训练效果的极性非特异性破坏有关。然后，我们使用线性弹道累加器模型来量化决策任务的潜在成分。此外，在 tDCS 治疗之前采集磁共振成像测量值，以量化皮质形态和局部神经化学浓度。与假刺激（安慰剂）相比，阳极和阴极刺激都破坏了与学习相关的任务改善，但两种极性的刺激对潜在任务成分有不同的影响。阳极刺激往往会影响行为任务的决策阈值，而阴极刺激则会改变证据积累率。此外，与阳极刺激相关的性能可变性与额下回皮质厚度有关，而与阴极刺激相关的性能可变性与下前中央沟皮质厚度以及前额叶神经化学兴奋性有关。我们的研究结果表明，皮质形态和局部神经化学平衡都是个体对电脑刺激行为反应差异的重要决定因素。
