Geometric determinants of human spatial memory

Abstract

Geometric alterations to the boundaries of a virtual environment were used to investigate the representations underlying human spatial memory. Subjects encountered a cue object in a simple rectangular enclosure, with distant landmarks for orientation. After a brief delay, during which they were removed from the arena, subjects were returned to it at a new location and orientation and asked to mark the place where the cue had been. On some trials the geometry (size, aspect ratio) of the arena was varied between presentation and testing. Responses tended to lie somewhere between a location that maintained fixed distances from nearby walls and a location that maintained fixed ratios of the distances between opposing walls. The former were more common after expansions and for cued locations nearer to the edge while the latter were more common after contractions and for locations nearer to the center. The spatial distributions of responses predicted by various simple geometric models were compared to the data. The best fitting model was one derived from the response properties of 'place cells' in the rat hippocampus, which matches the 'proximities' 1=ðd þ cÞ of the cue to the four walls of the arena, where d is the distance to a wall and c is a global constant. Subjects also tended to adopt the same orientation at presentation and testing, although this was not due to using a view matching strategy, which could be ruled out in 50% of responses. Disoriented responses were most often seen where the cued location was near the center of the arena or where the long axis of a rectangular arena was changed between presentation and testing, suggesting that the geometry of the arena acts as a weak cue to orientation. Overall, the results suggest a process of visual landmark matching to determine orientation, combined with an abstract representation of the proximity of the cued location to the walls of the arena consistent with the neural representation of location in the hippocampus. q

Distinct error-correcting and incidental learning of location relative to landmarks and boundaries

“…Otherwise, orientation might depend on many types of cue, combining outside of the hippocampus in the head-direction circuit (43) and possibly by associative reinforcement. Thus, asymmetrical boundary geometry and distal cues combine to orient participants (44) [and place cell firing (45)] and can overshadow and block each other in doing so (8,9,46,47). Whether or not distal cues do block each other in determining orientation depends on many factors, including task instructions (O. Hardt, A. Humpbach, and L. Nadel, unpublished data).…”

25 years of research on the use of geometry in spatial reorientation: a current theoretical perspective

“…Lee et al (2012) found that the relative lengths of isolated walls are not used to locate hidden objects but that, instead, the distances of the walls are important, perhaps based neurophysiologically on boundary vector cells (discussed further below; Burgess, Jackson, Hartley, & O'Keefe, 2000;Hartley, Burgess, Lever, Caccuci, & O'Keefe, 2000;Lever, Burton, Jeewajee, O'Keefe, & Burgess, 2009; see also Hartley, Trinkler, & Burgess, 2004, for some relevant human behavioral data). These cells (found in rats) fire most when the animal is at a particular distance from a surface.…”

Spatial Thinking by Young Children: Neurologic Evidence for Early Development and “Educability”

“…" Regardless of what terms are used, the distinction between conditions and connections is important, partly because the human brain appears to acquire and store information about place (conditions) and movement (connections) in different modes. "These strategies [spatial thinking by associating landmarks and tracing routes] may be subserved by different cortical areas [in the brain]" (Aginsky et al 1997, 317; see also Burwell et al 2004;Ekstrom et al 2003;Ferguson and Hegarty 1994;Golledge et al 1995;Gouteux et al 2001;Hartley et al 2004;Newcombe et al 1998).…”

“…Apparently it uses an interconnected system of at least three different brain areas that separately encode relative locations according to different frames of reference (Committeri et al 2004;Hartley et al 2004; and more than sixty other studies). One of those frames of reference is based on the geometric characteristics of everyday objects.…”