Department of Psychology, Northeastern University, Boston, Massachusetts 02115.
Department of Psychology, Emory University, Atlanta, Georgia 30322.
J Neurosci. 2024 Jun 26;44(26):e1757232024. doi: 10.1523/JNEUROSCI.1757-23.2024.
The periaqueductal gray (PAG) is a small midbrain structure that surrounds the cerebral aqueduct, regulates brain-body communication, and is often studied for its role in "fight-or-flight" and "freezing" responses to threat. We used ultra-high-field 7 T fMRI to resolve the PAG in humans and distinguish it from the cerebral aqueduct, examining its in vivo function during a working memory task ( = 87). Both mild and moderate cognitive demands elicited spatially similar patterns of whole-brain blood oxygenation level-dependent (BOLD) response, and moderate cognitive demand elicited widespread BOLD increases above baseline in the brainstem. Notably, these brainstem increases were not significantly greater than those in the mild demand condition, suggesting that a subthreshold brainstem BOLD increase occurred for mild cognitive demand as well. Subject-specific masks were group aligned to examine PAG response. In PAG, both mild and moderate demands elicited a well-defined response in ventrolateral PAG, a region thought to be functionally related to anticipated painful threat in humans and nonhuman animals-yet, the present task posed only the most minimal (if any) "threat," with the cognitive tasks used being approximately as challenging as remembering a phone number. These findings suggest that the PAG may play a more general role in visceromotor regulation, even in the absence of threat.
导水管周围灰质(periaqueductal gray,PAG)是一种环绕脑水管的中脑小结构,调节脑-体通讯,其在“战斗或逃跑”和“冻结”对威胁的反应中的作用常被研究。我们使用超高场 7T fMRI 来分辨人类的 PAG 并将其与脑水管区分开来,研究其在工作记忆任务中的体内功能(n=87)。轻度和中度认知需求都引起了全脑血氧水平依赖(blood oxygenation level-dependent,BOLD)反应的空间相似模式,而中度认知需求引起了脑干内广泛的 BOLD 基线以上增加。值得注意的是,这些脑干增加并不明显大于轻度需求条件,表明轻度认知需求也会引起亚阈值脑干 BOLD 增加。个体特异性掩模通过组对齐来检查 PAG 反应。在 PAG 中,轻度和中度需求都在腹外侧 PAG 引起了明确的反应,腹外侧 PAG 被认为与人类和非人类动物对预期疼痛威胁的功能有关——然而,本任务仅构成了最轻微的(如果有的话)“威胁”,所使用的认知任务与记住电话号码一样具有挑战性。这些发现表明,即使在没有威胁的情况下,PAG 也可能在内脏运动调节中发挥更普遍的作用。