Institute for Human Neuroscience, Boys Town National Research Hospital, Boys Town, NE, USA.
College of Medicine, University of Nebraska Medical Center, Omaha, NE, USA.
Psychol Med. 2023 Mar;53(4):1205-1214. doi: 10.1017/S0033291721002671. Epub 2021 Sep 22.
Cannabis is the most widely used illicit drug in the United States and is often associated with changes in attention function, which may ultimately impact numerous other cognitive faculties (e.g. memory, executive function). Importantly, despite the increasing rates of cannabis use and widespread legalization in the United States, the neural mechanisms underlying attentional dysfunction in chronic users are poorly understood.
We used magnetoencephalography (MEG) and a modified Posner cueing task in 21 regular cannabis users and 32 demographically matched non-user controls. MEG data were imaged in the time-frequency domain using a beamformer and peak voxel time series were extracted to quantify the oscillatory dynamics underlying use-related aberrations in attentional reorienting, as well as the impact on spontaneous neural activity immediately preceding stimulus onset.
Behavioral performance on the task (e.g. reaction time) was similar between regular cannabis users and non-user controls. However, the neural data indicated robust theta-band synchronizations across a distributed network during attentional reorienting, with activity in the bilateral inferior frontal gyri being markedly stronger in users relative to controls ('s < 0.036). Additionally, we observed significantly reduced spontaneous theta activity across this distributed network during the pre-stimulus baseline in cannabis users relative to controls ('s < 0.020).
Despite similar performance on the task, we observed specific alterations in the neural dynamics serving attentional reorienting in regular cannabis users compared to controls. These data suggest that regular cannabis users may employ compensatory processing in the prefrontal cortices to efficiently reorient their attention relative to non-user controls.
大麻是美国使用最广泛的非法药物，常与注意力功能改变相关，而注意力功能改变可能最终会影响到许多其他认知功能（例如记忆、执行功能）。重要的是，尽管美国大麻使用的比例不断增加，且大麻在全美范围内广泛合法化，但慢性使用者注意力功能障碍的神经机制仍知之甚少。
我们在 21 名经常使用大麻的人和 32 名年龄匹配的非使用者对照中使用了脑磁图（MEG）和改良的 Posner 线索任务。MEG 数据在时频域中使用波束形成器进行成像，并提取峰值体素时间序列，以量化注意力重新定向中与使用相关的异常的振荡动力学，以及对刺激出现前自发神经活动的影响。
任务的行为表现（例如反应时间）在经常使用大麻的人和非使用者对照之间相似。然而，神经数据表明，在注意力重新定向过程中，分布式网络中的θ带同步性很强，双侧额下回的活动在使用者中明显比对照组更强（'s < 0.036）。此外，我们观察到在大麻使用者中，与对照组相比，在刺激前基线期间，整个分布式网络的自发θ活动明显减少（'s < 0.020）。
尽管在任务表现上相似，但我们观察到经常使用大麻的人与对照组相比，注意力重新定向的神经动力学存在特定改变。这些数据表明，经常使用大麻的人可能会在前额叶皮层中采用代偿性处理，以便相对于非使用者对照更有效地重新定向注意力。
