Navigation strategy as a predictor of navigation performance

Navigation strategy as a predictor of navigation performance M. Kirk Rodgers (az7141@wayne.edu) Institute of Gerontology, 87 E. Ferry St. Detroit, MI 48201 USA Joseph A. Sindone, III (au0798@wayne.edu) Institute of Gerontology, 87 E. Ferry St. Detroit, MI 48201 USA Scott D. Moffat (moffat@wayne.edu) Institute of Gerontology, 87 E. Ferry St Detroit, MI 48201 USA Abstract Navigation strategy is an important component of spatial navigation. In the present study, we developed an assessment of human navigation strategy using a virtual analog of an assessment of animal navigation strategy. We examined the relationship between age, sex, and navigation strategy preference on subsequent performance of the virtual Morris Water Task (vMWT). On our novel assessment of navigation strategy, individuals were highly consistent in preferring either an allocentric or egocentric strategy. There were also substantial group differences in strategy preference with older adults overwhelmingly preferring an egocentric strategy, while younger adults were evenly divided between strategies. There were no significant sex differences in navigation strategy. On subsequent vMWT testing, allocentric strategy preference was associated with more accurate probe trial performance and enhanced cognitive mapping. These results suggest that human navigation strategy can be assessed reliably and that these strategy preferences feed forward to influence performance on independent navigation tasks. Keywords: Navigation; strategy; humans; aging; older adults; cognitive mapping Introduction Age and sex differences are commonly found in both human and animal models of navigation performance (Barnes et al. 1980; Driscoll et al. 2005; Ingram 1988; McLay et al. 1999; Moffat et al. 2001; Newman and Kaszniak 2000; Wilkniss et al. 1997). The hippocampus (HC) is part of a wide network of structures involved in spatial navigation, and has been consistently demonstrated to play a role in allocentric/world-centered spatial processing. Conversely, egocentric/self-centered processing is thought to involve primarily parietal cortex and caudate nucleus (Bohbot et al 2007; Maguire et al. 1998). Functional neuroimaging studies have demonstrated that older adult humans show less HC involvement during spatial navigation than do younger adults (Meulenbroek et al. 2004; Moffat et al. 2006; Antonova et al. 2009). In younger adults, it is thought that HC differences between males and females might underlie the widely reported finding of better male performance on spatial tasks (Astur et al., 1998). Some researchers have theorized that reduced HC involvement in navigation in older adults might reflect changes in navigation strategy as older adults adopt extra- hippocampal strategies. (Moffat et al. 2007; Moffat et al. 2006; Iaria et al. 2009). Some preliminary evidence supports this perspective. Driscoll et al. (2005) found that self-reported allocentric strategy use declined with age. Barnes and Colleagues (1980) investigated age differences in navigation strategy using a rat model in a modified T-maze. Rats were placed in one arm of the T- maze, and one of the remaining two arms was baited. The researchers included three types of cues in the environment that the rats could have used to learn the position of the goal: allocentric, based on objects in the environment, egocentric, based on the path taken by the rat, and cue, which took the form of a textured mat. Rats were trained to a criterion level of performance that demonstrated they had learned to reach the goal. Barnes then performed probe trials in which one of the cues was rotated 180 degrees. If the rat changed its path to “follow” the rotated cue, they were considered to be using that strategy. Multiple probes were completed, and Barnes and colleagues were able to calculate probabilities for strategy preference for each group. Older rats were more likely than Figure 1: Experimental sequence of Y-maze tasks including sample training paths