Chen J, Honey C J, Simony E, Arcaro M J, Norman K A, Hasson U
Princeton Neuroscience Institute and.
Department of Psychology, Princeton University, Princeton, NJ 08544, USA.
Cereb Cortex. 2016 Aug;26(8):3428-3441. doi: 10.1093/cercor/bhv155. Epub 2015 Aug 3.
It is well known that formation of new episodic memories depends on hippocampus, but in real-life settings (e.g., conversation), hippocampal amnesics can utilize information from several minutes earlier. What neural systems outside hippocampus might support this minutes-long retention? In this study, subjects viewed an audiovisual movie continuously for 25 min; another group viewed the movie in 2 parts separated by a 1-day delay. Understanding Part 2 depended on retrieving information from Part 1, and thus hippocampus was required in the day-delay condition. But is hippocampus equally recruited to access the same information from minutes earlier? We show that accessing memories from a few minutes prior elicited less interaction between hippocampus and default mode network (DMN) cortical regions than accessing day-old memories of identical events, suggesting that recent information was available with less reliance on hippocampal retrieval. Moreover, the 2 groups evinced reliable but distinct DMN activity timecourses, reflecting differences in information carried in these regions when Part 1 was recent versus distant. The timecourses converged after 4 min, suggesting a time frame over which the continuous-viewing group may have relied less on hippocampal retrieval. We propose that cortical default mode regions can intrinsically retain real-life episodic information for several minutes.
众所周知,新的情景记忆的形成依赖于海马体,但在现实生活场景中(例如对话),海马体失忆症患者能够利用几分钟前的信息。海马体之外的哪些神经系统可能支持这种长达数分钟的信息保留呢?在本研究中,受试者连续观看一部视听电影25分钟;另一组则分两部分观看这部电影,中间间隔一天。理解第二部分依赖于从第一部分提取信息,因此在间隔一天的情况下需要海马体。但是,从几分钟前获取相同信息时,海马体的参与程度是否相同呢?我们发现,与提取一天前相同事件的记忆相比,提取几分钟前的记忆时,海马体与默认模式网络(DMN)皮层区域之间的相互作用更少,这表明近期信息的获取对海马体检索的依赖程度较低。此外,两组呈现出可靠但不同的DMN活动时间进程,反映出当第一部分是近期信息与远期信息时,这些区域所承载信息的差异。4分钟后,时间进程趋于一致,这表明连续观看组可能在4分钟后对海马体检索的依赖程度降低。我们提出,皮层默认模式区域能够内在地保留现实生活中的情景信息达数分钟之久。