The 'cognitive map' hypothesis proposes that brain builds a unified representation of the spatial environment to support memory and guide future action. Forty years of electrophysiological research in rodents suggests that cognitive maps are neurally instantiated by place, grid, border, and head direction cells in the hippocampal formation and related structures. Here we review recent work that suggests a similar functional organization in the human brain and reveals novel insights into how cognitive maps are used during spatial navigation. Specifically, these studies indicate that: (i) the human hippocampus and entorhinal cortex support map-like spatial codes; (ii) posterior brain regions such as parahippocampal and retrosplenial cortices provide critical inputs that allow cognitive maps to be anchored to fixed environmental landmarks; (iii) hippocampal and entorhinal spatial codes are used in conjunction with frontal lobe mechanisms to plan routes during navigation. We also discuss how these three basic elements of cognitive map based navigation-spatial coding, landmark anchoring, and route planning-might be applied to non-spatial domains to provide the building blocks for many core elements of human thought.4

Past experience provides a rich source of predictive information about the world that could be used to guide and optimize ongoing perception. However, the neural mechanisms that integrate information coded in long-term memory (LTM) with ongoing perceptual processing remain unknown. Here, we explore how the contents of LTM optimize perception by modulating anticipatory brain states. By using a paradigm that integrates LTM and attentional orienting, we first demonstrate that the contents of LTM sharpen perceptual sensitivity for targets presented at memory-predicted spatial locations. Next, we examine oscillations in EEG to show that memory-guided attention is associated with spatially specific desynchronization of alpha-band activity over visual cortex. Additionally, we use functional MRI to confirm that target-predictive spatial information stored in LTM triggers spatiotopic modulation of preparatory activity in extrastriate visual cortex. Finally, functional MRI results also implicate an integrated cortical network, including the hippocampus and a dorsal frontoparietal circuit, as a likely candidate for organizing preparatory states in visual cortex according to the contents of LTM. O ur expectations shape how we see the world. From the earliest pioneers in perception (e.g., ref. 1), it has long been appreciated that past experience guides perceptual processing and decision-making. Indeed, the statistical regularities of the environment, extracted over past experience and coded in longterm memory (LTM), provide a rich source of predictive information that could be exploited to optimize perception for goal-directed behavior (2-4).Studies of selective attention provide an important framework for understanding the dynamic changes in neural processing that optimize perceptual analysis for goal-specific input. In particular, influential theories suggest that modulations in baseline neural activity in sensory cortex bias perceptual processing in favor of behaviorally relevant information (5-7). For example, a cue stimulus that provides information about the likely location of a target triggers a shift in baseline activity for neurons that represent the cued position (8-11), thereby increasing the neural sensitivity for subsequent stimulation at the attended region of space (10, 11). However, in everyday life, we rarely enjoy the benefit of explicit cues to guide our attention. More typically, we must rely on our own past experiences, stored in LTM, to build the predictions that shape perception for goal-directed behavior.Despite the obvious biological relevance of experience-based perceptual biasing, few studies have directly examined how memory influences attentional control. Studies of contextual cueing (2) demonstrate a close relationship between past experience and visual search efficiency: search times decrease with repeated exposure to the same stimulus configurations, even when repetitions are not explicitly processed (12). Contextual cueing effects are particularly compelling for detail-rich naturalistic scen...

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