title: The hippocampus and entorhinal cortex encode the path and Euclidean distances to goals during navigation.
abstract: BACKGROUND
  Despite decades of research on spatial memory, we know surprisingly little about how the brain guides navigation to goals. While some models argue that vectors are represented for navigational guidance, other models postulate that the future path is computed. Although the hippocampal formation has been implicated in processing spatial goal information, it remains unclear whether this region processes path- or vector-related information.
  
  
  RESULTS
  We report neuroimaging data collected from subjects navigating London's Soho district; these data reveal that both the path distance and the Euclidean distance to the goal are encoded by the medial temporal lobe during navigation. While activity in the posterior hippocampus was sensitive to the distance along the path, activity in the entorhinal cortex was correlated with the Euclidean distance component of a vector to the goal. During travel periods, posterior hippocampal activity increased as the path to the goal became longer, but at decision points, activity in this region increased as the path to the goal became closer and more direct. Importantly, sensitivity to the distance was abolished in these brain areas when travel was guided by external cues.
  
  
  CONCLUSIONS
  The results indicate that the hippocampal formation contains representations of both the Euclidean distance and the path distance to goals during navigation. These findings argue that the hippocampal formation houses a flexible guidance system that changes how it represents distance to the goal depending on the fluctuating demands of navigation.
authors.affiliation: UCL Institute of Behavioural Neuroscience, Research Department of Experimental Psychology, Division of Psychology and Language Sciences, University College London, London WC1H 0AP, UK; Aging & Cognition Research Group, German Center for Neurodegenerative Diseases (DZNE), 39120 Magdeburg, Germany.
authors.forename: Lorelei R
authors.initials: LR
authors.lastname: Howard
authors.affiliation: UCL Institute of Behavioural Neuroscience, Research Department of Experimental Psychology, Division of Psychology and Language Sciences, University College London, London WC1H 0AP, UK.
authors.forename: Amir Homayoun
authors.initials: AH
authors.lastname: Javadi
authors.affiliation: UCL Centre for Advanced Biomedical Imaging, University College London, London WC1E 6DD, UK.
authors.forename: Yichao
authors.initials: Y
authors.lastname: Yu
authors.affiliation: School of Psychology & Neuroscience, University of St. Andrews, Fife KY16 9JP, UK.
authors.forename: Ravi D
authors.initials: RD
authors.lastname: Mill
authors.affiliation: UCL Institute of Behavioural Neuroscience, Research Department of Experimental Psychology, Division of Psychology and Language Sciences, University College London, London WC1H 0AP, UK.
authors.forename: Laura C
authors.initials: LC
authors.lastname: Morrison
authors.affiliation: Department of Psychology, University of Hertfordshire, Hertfordshire AL10 9AB, UK.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Knight
authors.affiliation: UCL Institute of Behavioural Neuroscience, Research Department of Experimental Psychology, Division of Psychology and Language Sciences, University College London, London WC1H 0AP, UK.
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Loftus
authors.affiliation: UCL Institute of Behavioural Neuroscience, Research Department of Experimental Psychology, Division of Psychology and Language Sciences, University College London, London WC1H 0AP, UK.
authors.forename: Laura
authors.initials: L
authors.lastname: Staskute
authors.affiliation: UCL Institute of Behavioural Neuroscience, Research Department of Experimental Psychology, Division of Psychology and Language Sciences, University College London, London WC1H 0AP, UK. Electronic address: h.spiers@ucl.ac.uk.
authors.forename: Hugo J
authors.initials: HJ
authors.lastname: Spiers
mesh_terms: D000328:Adult; D003463:Cues; D018728:Entorhinal Cortex / Q000502:physiology*; D006624:Hippocampus / Q000502:physiology*; D006801:Humans; D008131:London; D008297:Male; D009949:Orientation; D065854:Spatial Navigation; D013702:Temporal Lobe / Q000502:physiology*; D055815:Young Adult