Modern psychological theories of spatial cognition postulate the existence of a ‘geometric module ’ for reorientation. This concept is derived from experimental data showing that in rectangular arenas with distinct landmarks in the corners, disoriented rats often make diagonal errors, suggesting their preference for the geometric (arena shape) over the non-geometric (landmarks) cues. Moreover, experimentally observed sensitivity of hippocampal cell firing to the changes in the environment layout was taken in support of the geometric module hypothesis. Using a computational model of rat navigation, we propose and test the alternative hypothesis that the influence of spatial geometry on both behavioral and neuronal levels can be explained by the properties of visual features that constitute local views of the environment. Our modeling results suggest that the pattern of diagonal errors observed in the reorientation task can be understood by the analysis of sensory information processing that underlies the navigation strategy employed

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Recent advances in the understanding of spatial cognition are reviewed, focusing on memory for locations in large-scale space and on those advances inspired by single-unit recording and lesion studies in animals. Spatial memory appears to be supported by multiple parallel representations, including egocentric and allocentric representations, and those updated to accommodate selfmotion. The effects of these representations can be dissociated behaviorally, developmentally, and in terms of their neural bases. It is now becoming possible to construct a mechanistic neural-level model of at least some aspects of spatial memory and imagery, with the hippocampus and medial temporal lobe providing allocentric environmental representations, the parietal lobe egocentric representations, and the retrosplenial cortex and parieto-occipital sulcus allowing both types of representation to interact. Insights from this model include a common mechanism for the construction of spatial scenes in the service of both imagery and episodic retrieval and a role for the remainder of Papez’s circuit in orienting the viewpoint used. In addition, it appears that hippocampal and striatal systems process different aspects of environmental layout (boundaries and local landmarks, respectively) and do so using different learning rules (incidental learning and associative reinforcement, respectively).

■ Maintaining spatial orientation while travelling requires integrating spatial information encountered from an egocentric viewpoint with accumulated information represented within egocentric and/or allocentric reference frames. Here, we report changes in high-density electroencephalographic (EEG) activity during a virtual tunnel passage task in which subjects respond to a postnavigation homing challenge in distinctly different ways— either compatible with a continued experience of the virtual environment from a solely egocentric perspective or as if also maintaining their original entrance orientation, indicating use of a parallel allocentric reference frame. By spatially filtering the EEG data using independent component analysis, we found that these two equal subject subgroups exhibited differences in EEG

This paper summarizes our recent attempts to integrate action and perception within a single optimization framework. We start with a statistical formulation of Helmholtz’s ideas about neural energy to furnish a model of perceptual inference and learning that can explain a remarkable range of neurobiological facts. Using constructs from statistical physics it can be shown that the problems of inferring the causes of our sensory inputs and learning regularities in the sensorium can be resolved using exactly the same principles. Furthermore, inference and learning can proceed in a biologically plausible fashion. The ensuing scheme rests on Empirical Bayes and hierarchical models of how sensory information is generated. The use of hierarchical models enables the brain to construct prior expectations in a dynamic and contextsensitive fashion. This scheme provides a principled way to understand many aspects of the brain’s organization and responses. We will demonstrate the brain-like dynamics that this scheme entails by using models of bird songs that are based on chaotic attractors with autonomous dynamics. This provides a nice example of how nonlinear dynamics can be exploited by the brain to represent and predict dynamics in the environment.

Abstract Recent work by Hupbach et al. (2007, 2009) suggests that episodic memory for a previously studied list can be updated to include new items, if participants are reminded of the earlier list just prior to learning a new list. The key finding from the Hupbach studies was an asymmetric pattern of intrusions, whereby participants intruded numerous items from the second list when trying to recall the first list, but not vice-versa. Hupbach et al. explain this pattern in terms of a cellular reconsolidation process, whereby the first-list memory is rendered labile by the reminder, and the labile memory is then updated to include items from the second list. Here we show that contextual reinstatement and item-context binding within the Temporal Context Model (TCM) can account for the asymmetric intrusion effect. These results suggest that findings that (purportedly) show human reconsolidation are consistent with existing cognitive theories of human memory.

Recent work by Hupbach et al. (2007, 2009) suggests that episodic memory for a previously studied list can be updated to include new items, if participants are reminded of the earlier list just prior to learning a new list. The key finding from the Hupbach studies was an asymmetric pattern of intrusions, whereby participants intruded numerous items from the second list when trying to recall the first list, but not vice-versa. Hupbach et al. explain this pattern in terms of a cellular reconsolidation process, whereby the first-list memory is rendered labile by the reminder, and the labile memory is then updated to include items from the second list. Here we show that the Temporal Context Model (TCM) of memory, which lacks a cellular reconsolidation process, can account for the asymmetric intrusion effect using well-established principles of contextual reinstatement and item-context binding.

Abstract: Fodor advocates a view of cognitive processes as computations defined over the language of thought (or Mentalese). Even among those who endorse Mentalese, considerable controversy surrounds its representational format. What semantically relevant structure should scientific psychology attribute to Mentalese symbols? Researchers commonly emphasize logical structure, akin to that displayed by predicate calculus sentences. To counteract this tendency, I discuss computational models of navigation drawn from probabilistic robotics. These models involve computations defined over cognitive maps, which have geometric rather than logical structure. They thereby demonstrate the possibility of rational cognitive processes in an exclusively non-logical representational medium. Furthermore, they offer much promise for the empirical study of animal navigation.

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