Ventromedial prefrontal cortex drives the prioritization of self-associated stimuli in working memory

Humans show a pervasive bias for processing self- over other-related
information, including in working memory (WM), where people prioritize the
maintenance of self- (over other-) associated cues. To elucidate the
neural mechanisms underlying this self-bias, we paired a self- vs.
other-associated spatial WM task with functional magnetic resonance
imaging (fMRI) and transcranial direct current stimulation (tDCS).
Maintaining self- (over other-) associated cues resulted in enhanced
delay-period activity in classic WM regions (frontoparietal cortex), and
in superior multivoxel pattern decoding of the cue locations from visual
cortex. Moreover, ventromedial prefrontal cortex (VMPFC) displayed
enhanced functional connectivity with WM regions during maintenance of
self-associated cues, which predicted individuals’ behavioral
self-prioritization effects. In a follow-up tDCS experiment, we targeted
VMPFC with either excitatory (anodal), inhibitory (cathodal), or sham
tDCS. Cathodal tDCS eliminated the self-prioritization effect. These
findings provide strong converging evidence for a causal role of VMPFC in
driving self-prioritization effects in WM.

人类普遍存在加工自我相关信息优于他人相关信息的认知偏向，这一效应在工作记忆（working memory，WM）中亦有体现——个体优先维持与自我关联而非他人关联的线索。为阐明这一自我偏向背后的神经机制，我们将自我vs他人关联的空间工作记忆任务与功能磁共振成像（functional magnetic resonance imaging，fMRI）及经颅直流电刺激（transcranial direct current stimulation，tDCS）相结合。维持自我相关线索（相较于他人相关线索）可增强经典工作记忆脑区（额顶皮层）的延迟时段活动，并提升从视觉皮层解码线索位置的多体素模式识别准确率。此外，在维持自我相关线索期间，腹内侧前额叶皮层（ventromedial prefrontal cortex，VMPFC）与工作记忆脑区的功能连接性显著增强，该指标可预测个体的行为自我优先化效应。在后续的经颅直流电刺激实验中，我们对腹内侧前额叶皮层分别施加兴奋性（阳极）、抑制性（阴极）或伪刺激三种干预。结果显示，阴极经颅直流电刺激消除了自我优先化效应。上述发现为腹内侧前额叶皮层在驱动工作记忆中的自我优先化效应中发挥因果作用提供了强有力的汇聚性证据。