Retrospectively and prospectively modulated hippocampal place responses are differentially distributed along a common path in a continuous T-maze.
Journal of Neuroscience. 2014-09-24; 34(39): 13163-13169
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1. J Neurosci. 2014 Sep 24;34(39):13163-9. doi: 10.1523/JNEUROSCI.0819-14.2014.
Retrospectively and prospectively modulated hippocampal place responses are
differentially distributed along a common path in a continuous T-maze.
Catanese J(1), Viggiano A(2), Cerasti E(2), Zugaro MB(2), Wiener SI(1).
(1)College de France, Center for Interdisciplinary Research in Biology, Paris
F-75005, France, and CNRS, UMR 7241, Paris F-75005, France
(2)College de France, Center for Interdisciplinary Research in Biology, Paris
F-75005, France, and CNRS, UMR 7241, Paris F-75005, France.
Hippocampal place responses can be prospectively or retrospectively modulated by
the animal’s future or prior trajectory. Two main hypotheses explain this. The
« multiple-map hypothesis » switches between different maps for different
trajectories (rate remapping). In contrast, in the « buffer hypothesis, » the
hippocampus encodes an ongoing representation that includes the recent past
and/or the impending future choice. This study examines the distribution of
prospective and retrospective responses distributed along a common path in a
continuous T-maze (providing all four combinations of provenance and destination)
during a visual discrimination task. The multiple-map hypothesis predicts either
uniform distributions or concerted shifts about a task-decision relevant point,
whereas the buffer hypothesis predicts a time-limited overexpression around
choice points (with retrospective responses after the central arm entry point and
prospective responses nearer its exit). Here bilateral recordings in the dorsal
CA1 region of the rat hippocampus show that retrospective responses were twice as
prevalent as prospective responses. Furthermore, retrospective and prospective
modulations have distinct spatial distributions, with retrospective primarily in
the first two-thirds of the central arm and prospective restricted to the last
third. To test for possible trial-by-trial remapping in relation to the
two-thirds transition point, data from the first and second halves of the
sessions were compared. Backward drift of path-modulated activity was significant
only for retrospective, but not prospective, fields. Thus, these data are more
consistent with the buffer hypothesis. Retrospective and prospective modulation
would then participate in a single hippocampal representation of spatial and
Copyright © 2014 the authors 0270-6474/14/3413163-07$15.00/0.
PMID: 25253861 [Indexed for MEDLINE]