Hipocampo y desiciones

The Journal of Neuroscience, March 23, 2011 • 31(12):4613– 4621 • 4613

Behavioral/Systems/Cognitive

Anterior Hippocampus and Goal-Directed Spatial Decision Making
Armelle Viard,1,2 Christian F. Doeller,1,3,4 Tom Hartley,1,5 Chris M. Bird,1,3 and Neil Burgess1
1UCL Institute of Cognitive Neuroscience, University College London, London WC1N 3AR, United Kingdom, 2Inserm-EPHE-UCBN U923, GIPCyceron, 14074 Caen, France, 3UCL Institute of Neurology, University College London, London WC1N 3AR, United Kingdom, 4Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, Centre for Cognitive Neuroimaging 6525, The Netherlands, and 5Department of Psychology, University of York, York YO10 5DD, United Kingdom

Planning spatial paths through our environment is an importantpart of everyday life and is supported by a neural system including the hippocampus and prefrontal cortex. Here we investigated the precise functional roles of the components of this system in humans by using fMRI as participants performed a simple goal-directed route-planning task. Participants had to choose the shorter of two routes to a goal in a visual scene that might contain a barrier blockingthe most direct route, requiring a detour, or might be obscured by a curtain, requiring memory for the scene. The participant’s start position was varied to parametrically manipulate their proximity to the goal and the difference in length of the two routes. Activity in medial prefrontal cortex, precuneus, and left posterior parietal cortex was associated with detour planning, regardless ofdifficulty, whereas activity in parahippocampal gyrus was associated with remembering the spatial layout of the visual scene. Activity in bilateral anterior hippocampal formation showed a strong increase the closer the start position was to the goal, together with medial prefrontal, medial and posterior parietal cortices. Our results are consistent with computational models in which goal proximity isused to guide subsequent navigation and with the association of anterior hippocampal areas with nonspatial functions such as arousal and reward expectancy. They illustrate how spatial and nonspatial functions combine within the anterior hippocampus, and how these functions interact with parahippocampal, parietal, and prefrontal areas in decision making and mnemonic function.

Introduction
The neuralmechanisms supporting the planning of spatial routes remain a mystery, although single-unit recording and lesion and neuroimaging studies provide some tantalizing hints. Posterior hippocampal formation (HF) in humans (homologous to dorsal HF in rodents) is thought to encode environmental location to support spatial navigation (O’Keefe and Nadel, 1978; Maguire et al., 1998; Ekstrom et al., 2003;Hartley et al., 2003; Moser and Moser, 1998; Doeller et al., 2008; Moser et al., 2008), whereas anterior HF (homologous to rodent ventral HF) is associated with processing environmental context (Bannerman et al., 2004; Kjelstrup et al., 2008), novelty (Strange et al., 1999; Bunzeck and Duzel, 2006; Dudukovic and Wagner, 2007; Doeller et al., 2008), ¨ arousal, emotion, and reward (Moser and Moser,1998; Ferbinteanu and McDonald, 2001; Fanselow and Dong, 2010; Royer et al., 2010), and their effects on memory (Wittmann et al., 2005; Adcock et al., 2006). Spatial planning links representations of location with expectancy of reward to provide a basis for the appropriate choice of action (Sutton and Barto, 1998; Foster et al., 2000).
Received Sept. 3, 2010; revised Dec. 18, 2010; accepted Jan.24, 2011. This work was supported by the Wayfinding project of the European Union and the Medical Research Council (UK). We thank Hugo Spiers for useful discussions and help with initial task design, and the Wellcome Trust Centre for Neuroimaging at University College London for providing help and scanning facilities. Correspondence should be addressed to Neil Burgess, Institute of Cognitive...