Precision, binding, and the hippocampus: Precisely what are we talking about?

Endel Tulving's proposal that episodic memory is distinct from other memory systems like semantic memory remains an extremely influential idea in cognitive neuroscience research. As originally suggested by Tulving, episodic memory involves three key components that differentiate it from all other memory systems: spatiotemporal binding, mental time travel, and autonoetic consciousness. Here, we focus on the idea of spatiotemporal binding in episodic memory and, in particular, how consideration of the precision of spatiotemporal context helps expand our understanding of episodic memory. Precision also helps shed light on another key issue in cognitive neuroscience, the role of the hippocampus outside of episodic memory in perception, attention, and working memory. By considering precision alongside item-context bindings, we attempt to shed new light on both the nature of how we represent context and what roles the hippocampus plays in episodic memory and beyond.

Ekstrom AD ，Yonelinas AP 《-》

The radiation of autonoetic consciousness in cognitive neuroscience: A functional neuroanatomy perspective.

One of Endel Tulving's most important contributions to memory research is the coupling of self-knowing consciousness (or "autonoesis") with episodic memory. According to Tulving, autonoetic episodic memory enables the uniquely human neurocognitive operation of "mental time travel", which is the ability to deliberately "project" oneself to a specific time and place to remember personally experienced events that occurred in the past and simulate personal happenings that may occur in the future. These ideas ignited an explosion of research in the years to follow, leading to the development of several related concepts and theories regarding the role of the human self in memory and prospection. In this paper, we first explore the expansion of the concept of autonoetic consciousness in the cognitive neuroscience literature as well as the formulation of derivative concepts and theories. Subsequently, we review such concepts and theories including episodic memory, mental time travel, episodic simulation, scene construction and self-projection. In view of Tulving's emphasis of the temporal and spatial context of the experience, we also review the cognitive operation involved in "travel" (or "projection") in these domains as well as in the social domain. We describe the underlying brain networks and processes involved, their overlapping activations and involvement in giving rise to the experience. Meta-analysis of studies investigating the underlying functional neuroanatomy of these theories revealed main overlapping activations in sub-regions of the medial prefrontal cortex, the precuneus, retrosplenial cortex, temporoparietal junction and medial temporal lobe. Dissection of these results enables to infer and quantify the interrelations in between the different theories as well as with respect to Tulving's original ideas.

Dafni-Merom A ，Arzy S 《-》

Dissociating the past from the present in the activity of place cells.

It has been proposed that declarative memories can be dependent on both an episodic and a semantic memory system. While the semantic system deals with factual information devoid of reference to its acquisition, the episodic system, characterized by mental time travel, deals with the unique past experience in which an event took place. Episodic memory is characteristically hippocampus-dependent. Place cells are recorded from the hippocampus of rodents and their firing reflects many of the key characteristics of episodic memory. For example, they encode information about "what" happens "where," as well as temporal information. However, when these features are expressed during an animal's behavior, the neuronal activity could merely be categorizing the present situation and could therefore reflect semantic memory rather than episodic memory. We propose that mental time travel is the key feature of episodic memory and that it should take a form, in the awake animal, similar to the replay of behavioral patterns of activity that has been observed in hippocampus during sleep. Using tasks designed to evoke episodic memory, one should be able to see memory reactivation of behaviorally relevant sequences of activity in the awake animal while recording from hippocampus and other cortical structures.

de Hoz L ，Wood ER 《HIPPOCAMPUS》

Hippocampal place cells, context, and episodic memory.

Although most observers agree that the hippocampus has a critical role in learning and memory, there remains considerable debate about the precise functional contribution of the hippocampus to these processes. Two of the most influential accounts hold that the primary function of the hippocampus is to generate cognitive maps and to mediate episodic memory processes. The well-documented spatial firing patterns (place fields) of hippocampal neurons in rodents, along with the spatial learning impairments observed with hippocampal damage support the cognitive mapping hypothesis. The amnesia for personally experienced events seen in humans with hippocampal damage and the data of animal models, which show severe memory deficits associated with hippocampal lesions, support the episodic memory account. Although an extensive literature supports each of these hypotheses, a specific contribution of place cells to episodic memory has not been clearly demonstrated. Recent data from our laboratory, together with previous findings, indicate that hippocampal place fields and neuronal responses to task-relevant stimuli are highly sensitive to the context, even when the contexts are defined by abstract task demands rather than the spatial geometry of the environment. On the basis of these findings, it is proposed that place fields reflect a more general context processing function of the hippocampus. Hippocampal context representations could serve to differentiate contexts and prime the relevant memories and behaviors. Since episodic memories, by definition, include information about the time and place where the episode occurred, contextual information is a necessary prerequisite for any episodic memory. Thus, place fields contribute importantly to episodic memory as part of the needed context representations. Additionally, recent findings indicate that hippocampal neurons differentiate contexts at progressively finer levels of detail, suggesting a hierarchical coding scheme which, if combined with temporal information, could provide a means of differentiating memory episodes.

Smith DM ，Mizumori SJ 《HIPPOCAMPUS》

The history of episodic memory.

Hoerl C ，McCormack T 《-》