海马参与工作记忆目标匹配增强及其时间过程——基于颅内脑电的研究

已有的研究结果表明,海马参与记忆的编码和提取,并且它会受到新发生事件与已存储记忆匹配或者不匹配的影响.先前的功能磁共振研究报道,在延迟匹配任务中,目标匹配增强作为一种工作记忆成分,与物体性质和位置的整合有关,能够显著地激活海马体部.但是,关于这一过程的时间信息目前尚不清楚.本研究利用特定癫痫病人在双侧海马植入的深部电极,跨被试间电极触点位置基本一致,因此具有较高的空间分辨率和时间分辨率的优势.我们发现,左侧海马体部在目标匹配增强中起着重要作用.同时,这种效应发生在探测刺激出现后600～650 ms,大约在知觉匹配增强或者P300等知觉效应后200 ms.另外,对于每一个被试,目标匹配增强的潜伏期与平均反应时成正相关.结果揭示,当工作记忆的任务与性质-位置捆绑有关时,海马参与并起重要作用.结果说明,目标匹配增强效应在知觉过程之后发生,表明了工作记忆不同成分在海马的分离.

Timing of Goal Match Enhancement in The Hippocampus Revealed by Human Intracranial Recording

Hippocampus is involved in the memory encoding and retrieval, and its ability is influenced by the incoming events which match or mismatch the stored representation. Previous fMRI studies have reported that goal match enhancement, a component of working memory involving object identity and location, significantly activates the posterior hippocampus. However, information regarding the timing of this process is limited. In the current study, facilitated by the high spatial and temporal resolution of intracranial recording from human patients, we confirmed that the left posterior hippocampus plays an important role in the goal match enhancement effect. We also found that this effect occurs within 600 to 650 milliseconds of probe onset, about 200 ms later than perceptual effects such as the physical match enhancement effect or the P300. More specifically, within individuals, goal match enhancement latency is positively correlated with mean reaction time. The results suggest that the hippocampus plays an important role in working memory in tasks involving feature-location binding. The results further suggest that goal match enhancement effects occur after perceptual processes, implying a dissociation of different working memory components in the hippocampus.