Path shape impacts the extent of CA1 pattern recurrence both within and across environments

Nitz DA. Path shape impacts the extent of CA1 pattern recurrence both within and across environments. J Neurophysiol 105: 1815-1824, 2011. First published February 2, 2011; doi:10.1152/jn.00573.2010.Similarities and differences in the visual content, scale, and shape of environmental boundaries for two environments have been extensively examined for their impact on the recurrence of spatially specific hippocampal firing patterns across environments and across multiple regions of a single environment. Although the shapes of paths taken through an environment are known to impact hippocampal firing patterns within any single region of a single environment, it is not known to what extent path shape and scale can impact firing pattern recurrence across two environments and across multiple regions of a single environment. This question was addressed in the present work where the spatial firing patterns of hippocampal CA1 neurons were examined as rats traversed differently shaped spiral paths centered on the same position within a visually observable curtained enclosure. On such tracks, firing fields for CA1 neurons were found to recur across multiple subregions of a single path and across similarly positioned regions of different paths. Both within and across different spiral tracks, the extent of such pattern recurrence was strongly influenced by similarity in the specific sequences of movement directions and locomotor behaviors engendered by different path shapes. The findings demonstrate that the shapes of paths taken through an environment can robustly and dynamically alter both the scale of spatially specific CA1 firing fields and the extent to which they recur across environments.