Turner Institute for Brain and Mental Health, Monash University, Clayton, Victoria, Australia; Monash Biomedical Imaging, Monash University, Clayton, Victoria, Australia.
Department of Psychiatry, Psychotherapy & Psychosomatics, Psychiatric University Hospital Zurich, Zurich, Switzerland.
Biol Psychiatry. 2024 Jul 1;96(1):57-66. doi: 10.1016/j.biopsych.2024.01.002. Epub 2024 Jan 6.
Serotonergic psychedelics, such as psilocybin, alter perceptual and cognitive systems that are functionally integrated with the amygdala. These changes can alter cognition and emotions that are hypothesized to contribute to their therapeutic utility. However, the neural mechanisms of cognitive and subcortical systems altered by psychedelics are not well understood.
We used resting-state functional magnetic resonance images collected during a randomized, double-blind, placebo-controlled clinical trial of 24 healthy adults under 0.2 mg/kg psilocybin to estimate the directed (i.e., effective) changes between the amygdala and 3 large-scale resting-state networks involved in cognition. These networks are the default mode network, the salience network, and the central executive network.
We found a pattern of decreased top-down effective connectivity from these resting-state networks to the amygdala. Effective connectivity decreased within the default mode network and salience network but increased within the central executive network. These changes in effective connectivity were statistically associated with behavioral measures of altered cognition and emotion under the influence of psilocybin.
Our findings suggest that temporary amygdala signal attenuation is associated with mechanistic changes to resting-state network connectivity. These changes are significant for altered cognition and perception and suggest targets for research investigating the efficacy of psychedelic therapy for internalizing psychiatric disorders. More broadly, our study suggests the value of quantifying the brain's hierarchical organization using effective connectivity to identify important mechanisms for basic cognitive function and how they are integrated to give rise to subjective experiences.
血清素能迷幻剂，如裸盖菇素，改变与杏仁核功能整合的感知和认知系统。这些变化可以改变认知和情绪，这被假设为其治疗效用的贡献。然而，迷幻剂改变的认知和皮质下系统的神经机制尚不清楚。
我们使用在 24 名健康成年人中进行的随机、双盲、安慰剂对照临床试验中采集的静息态功能磁共振图像，来估计 0.2mg/kg 裸盖菇素对涉及认知的 3 个大尺度静息态网络（默认模式网络、突显网络和中央执行网络）与杏仁核之间的有向（即有效）变化。
我们发现这些静息态网络到杏仁核的自上而下的有效连通性呈下降趋势。默认模式网络和突显网络内的有效连通性下降，但中央执行网络内的有效连通性增加。这些有效连接的变化与裸盖菇素影响下认知和情绪改变的行为测量值具有统计学关联。
我们的研究结果表明，杏仁核信号的短暂衰减与静息态网络连接的机制变化有关。这些变化对于改变认知和感知非常重要，并为研究迷幻药治疗内化性精神障碍的疗效提供了目标。更广泛地说，我们的研究表明，使用有效连接来量化大脑的层次组织以确定基本认知功能的重要机制及其如何整合以产生主观体验的价值。
