Data from: Hippocampus is place of interaction between unconscious and conscious memories

Recent evidence suggests that humans can form and later retrieve new semantic relations unconsciously by way of hippocampus—the key structure also recruited for conscious relational (episodic) memory. If the hippocampus subserves both conscious and unconscious relational encoding/retrieval, one would expect the hippocampus to be place of unconscious-conscious interactions during memory retrieval. We tested this hypothesis in an fMRI experiment probing the interaction between the unconscious and conscious retrieval of face-associated information. For the establishment of unconscious relational memories, we presented subliminal (masked) combinations of unfamiliar faces and written occupations (“actor” or “politician”). At test, we presented the former subliminal faces, but now supraliminally, as cues for the reactivation of the unconsciously associated occupations. We hypothesized that unconscious reactivation of the associated occupation—actor or politician—would facilitate or inhibit the subsequent conscious retrieval of a celebrity’s occupation, which was also actor or politician. Depending on whether the reactivated unconscious occupation was congruent or incongruent to the celebrity’s occupation, we expected either quicker or delayed conscious retrieval process. Conscious retrieval was quicker in the congruent relative to a neutral baseline condition but not delayed in the incongruent condition. fMRI data collected during subliminal face-occupation encoding confirmed previous evidence that the hippocampus was interacting with neocortical storage sites of semantic knowledge to support relational encoding. fMRI data collected at test revealed that the facilitated conscious retrieval was paralleled by deactivations in the hippocampus and neocortical storage sites of semantic knowledge. We assume that the unconscious reactivation has pre-activated overlapping relational representations in the hippocampus reducing the neural effort for conscious retrieval. This finding supports the notion of synergistic interactions between conscious and unconscious relational memories in a common, cohesive hippocampal-neocortical memory space.

最新研究证据表明，人类可通过海马体（hippocampus）无意识地形成并后续提取新的语义关联，而该关键脑结构同样参与有意识的关系型（情景）记忆加工。若海马体同时支撑有意识与无意识的关系型编码/提取过程，则可推测在记忆提取阶段，海马体将成为无意识-有意识交互作用的发生位点。我们通过一项功能性磁共振成像（fMRI）实验验证了该假设，实验聚焦于面孔关联信息的无意识提取与有意识提取间的交互机制。为构建无意识关系记忆，我们向被试呈现了阈下（掩蔽）配对刺激：陌生面孔与文字职业标签（“演员”或“政治家”）。在测试阶段，我们将此前呈现的阈下面孔以阈上形式呈现，作为线索以重新激活被试无意识中关联的职业信息。我们提出假设：被无意识激活的关联职业（演员或政治家），会对后续有意识提取某位名人职业的任务产生促进或抑制作用——该名人的职业同样为演员或政治家。根据被无意识激活的职业与名人职业是否一致，我们推测有意识提取过程会相应加快或延迟。相较于中性基线条件，一致条件下的有意识提取速度更快，但不一致条件下并未出现提取延迟现象。阈下面孔-职业编码阶段采集的fMRI数据验证了既往研究结论：海马体与存储语义知识的新皮层脑区存在交互作用，以支撑关系型编码过程。测试阶段采集的fMRI数据显示，伴随有意识提取的促进效应，海马体与语义知识的新皮层存储脑区均出现了激活下调现象。我们推测，无意识激活过程已在海马体中预先激活了重叠的关系表征，从而降低了有意识提取所需的神经负荷。该发现支持了这一观点：在统一且协同的海马体-新皮层记忆网络中，有意识与无意识关系记忆间存在协同交互作用。