Matthew Buckley, Anthony McGregor, Niklas Ihssen, Joseph Austen, Simon Thurlbeck, Shamus P. Smith, Armin Heinecke, Adina R. Lew
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引用次数: 0
Abstract
Classic research has shown a division in the neuroanatomical structures that support flexible (e.g., short-cutting) and habitual (e.g., familiar route following) navigational behavior, with hippocampal–caudate systems associated with the former and putamen systems with the latter. There is, however, disagreement about whether the neural structures involved in navigation process particular forms of spatial information, such as associations between constellations of cues forming a cognitive map, versus single landmark-action associations, or alternatively, perform particular reinforcement learning algorithms that allow the use of different spatial strategies, so-called model-based (flexible) or model-free (habitual) forms of learning. We sought to test these theories by asking participants (N = 24) to navigate within a virtual environment through a previously learned, 9-junction route with distinctive landmarks at each junction while undergoing functional magnetic resonance imaging (fMRI). In a series of probe trials, we distinguished knowledge of individual landmark-action associations along the route versus knowledge of the correct sequence of landmark-action associations, either by having absent landmarks, or “out-of-sequence” landmarks. Under a map-based perspective, sequence knowledge would not require hippocampal systems, because there are no constellations of cues available for cognitive map formation. Within a learning-based model, however, responding based on knowledge of sequence would require hippocampal systems because prior context has to be utilized. We found that hippocampal–caudate systems were more active in probes requiring sequence knowledge, supporting the learning-based model. However, we also found greater putamen activation in probes where navigation based purely on sequence memory could be planned, supporting models of putamen function that emphasize its role in action sequencing.
期刊介绍:
Hippocampus provides a forum for the exchange of current information between investigators interested in the neurobiology of the hippocampal formation and related structures. While the relationships of submitted papers to the hippocampal formation will be evaluated liberally, the substance of appropriate papers should deal with the hippocampal formation per se or with the interaction between the hippocampal formation and other brain regions. The scope of Hippocampus is wide: single and multidisciplinary experimental studies from all fields of basic science, theoretical papers, papers dealing with hippocampal preparations as models for understanding the central nervous system, and clinical studies will be considered for publication. The Editor especially encourages the submission of papers that contribute to a functional understanding of the hippocampal formation.