The hippocampus and parahippocampal region are essential for representing episodic memories involving various spatial locations and objects, and for using those memories for future adaptive behavior. The “dual-stream model” was initially formulated based on anatomical characteristics of the medial temporal lobe, dividing the parahippocampal region into two streams that separately process and relay spatial and nonspatial information to the hippocampus. Despite its significance, the dual-stream model in its original form cannot explain recent experimental results, and many researchers have recognized the need for a modification of the model. Here, we argue that dividing the parahippocampal region into spatial and nonspatial streams a priori may be too simplistic, particularly in light of ambiguous situations in which a sensory cue alone (e.g., visual scene) may not allow such a definitive categorization. Upon reviewing evidence, including our own, that reveals the importance of goal-directed behavioral responses in determining the relative involvement of the parahippocampal processing streams, we propose the Goal-directed Interaction of Stimulus and Task-demand (GIST) model. In the GIST model, input stimuli such as visual scenes and objects are first processed by both the postrhinal and perirhinal cortices—the postrhinal cortex more heavily involved with visual scenes and perirhinal cortex with objects—with relatively little dependence on behavioral task demand. However, once perceptual ambiguities are resolved and the scenes and objects are identified and recognized, the information is then processed through the medial or lateral entorhinal cortex, depending on whether it is used to fulfill navigational or non-navigational goals, respectively. As complex sensory stimuli are utilized for both navigational and non-navigational purposes in an intermixed fashion in naturalistic settings, the hippocampus may be required to then put together these experiences into a coherent map to allow flexible cognitive operations for adaptive behavior to occur.

中文翻译：

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海马旁区域刺激与任务需求的目标导向相互作用

海马和海马旁区域对于表示涉及各种空间位置和对象的情景记忆以及将这些记忆用于未来的适应性行为至关重要。“双流模型”最初是根据内侧颞叶的解剖特征制定的，将海马旁区域分为两个流，分别处理和传递空间和非空间信息到海马。尽管具有重要意义，但原始形式的双流模型无法解释最近的实验结果，许多研究人员已经认识到需要对模型进行修改。在这里，我们认为将海马旁区域先验地分为空间流和非空间流可能过于简单化，特别是考虑到仅凭感觉线索的模棱两可的情况（例如，视觉场景）可能不允许这样明确的分类。在审查了包括我们自己在内的证据，这些证据揭示了目标导向的行为反应在确定海马旁处理流的相对参与方面的重要性，我们提出了目标导向的刺激和任务需求相互作用 (GIST) 模型。在 GIST 模型中，视觉场景和物体等输入刺激首先由鼻后皮层和鼻周皮层处理——鼻后皮层更多地参与视觉场景，鼻周皮层与物体相关——对行为任务需求的依赖性相对较小。然而，一旦感知模糊得到解决，场景和物体被识别和识别，信息就会通过内侧或外侧内嗅皮层进行处理，取决于它是分别用于实现导航目标还是非导航目标。由于在自然环境中以混合方式将复杂的感觉刺激用于导航和非导航目的，因此可能需要海马体将这些体验整合到一个连贯的地图中，以允许灵活的认知操作发生适应性行为。