Encoding and storage of spatial information in the retrosplenial cortex

Proc Natl Acad Sci U S A. 2014 Jun 10;111(23):8661-6. doi: 10.1073/pnas.1313222111. Epub 2014 May 27.

Abstract

The retrosplenial cortex (RSC) is part of a network of interconnected cortical, hippocampal, and thalamic structures harboring spatially modulated neurons. The RSC contains head direction cells and connects to the parahippocampal region and anterior thalamus. Manipulations of the RSC can affect spatial and contextual tasks. A considerable amount of evidence implicates the role of the RSC in spatial navigation, but it is unclear whether this structure actually encodes or stores spatial information. We used a transgenic mouse in which the expression of green fluorescent protein was under the control of the immediate early gene c-fos promoter as well as time-lapse two-photon in vivo imaging to monitor neuronal activation triggered by spatial learning in the Morris water maze. We uncovered a repetitive pattern of cell activation in the RSC consistent with the hypothesis that during spatial learning an experience-dependent memory trace is formed in this structure. In support of this hypothesis, we also report three other observations. First, temporary RSC inactivation disrupts performance in a spatial learning task. Second, we show that overexpressing the transcription factor CREB in the RSC with a viral vector, a manipulation known to enhance memory consolidation in other circuits, results in spatial memory enhancements. Third, silencing the viral CREB-expressing neurons with the allatostatin system occludes the spatial memory enhancement. Taken together, these results indicate that the retrosplenial cortex engages in the formation and storage of memory traces for spatial information.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cyclic AMP Response Element-Binding Protein / metabolism
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Gyrus Cinguli / cytology
  • Gyrus Cinguli / metabolism
  • Gyrus Cinguli / physiology*
  • Hippocampus / cytology
  • Hippocampus / metabolism
  • Hippocampus / physiology*
  • Maze Learning / physiology
  • Memory / physiology*
  • Mice
  • Mice, 129 Strain
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Microscopy, Confocal / methods
  • Microscopy, Fluorescence, Multiphoton / methods
  • Neurons / cytology
  • Neurons / metabolism
  • Neurons / physiology
  • Promoter Regions, Genetic / genetics
  • Proto-Oncogene Proteins c-fos / genetics
  • Space Perception / physiology*

Substances

  • Creb1 protein, mouse
  • Cyclic AMP Response Element-Binding Protein
  • Proto-Oncogene Proteins c-fos
  • Green Fluorescent Proteins