Czajkowski, R., Jayaprakash, B., Wiltgen, B., Rogerson, T., Guzman-Karlsson, M. C., Barth, A. L., Trachtenberg, J. T., & Silva, A. J. (2014). Encoding and storage of spatial information in the retrosplenial cortex. Proceedings of the National Academy of Sciences of the United States of America, 111(23), 8661–8666. https://doi.org/10.1073/pnas.1313222111

SIGNIFICANCE
“The retrosplenial cortex (RSC) is a key part of a network of brain regions that processes and stores spatial information. However, it is unclear whether the RSC actually encodes or stores spatial information. With time-lapse two-photon in vivo imaging that allowed us to study the immediate early gene c-fos expression in tens of thousands of cells in the RSC, we uncovered repetitive activation of a fraction of cells in this structure during spatial learning. We also showed that RSC inactivation disrupts performance in a spatial task, whereas overexpressing of the transcription factor CREB results in enhanced spatial memory. Silencing the CREB-expressing neurons occluded these memory enhancements. These results demonstrate that the retrosplenial cortex is involved in the formation and storage of spatial information.”

 
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.”

Czajkowski, R., Jayaprakash, B., Wiltgen, B., Rogerson, T., Guzman-Karlsson, M. C., Barth, A. L., Trachtenberg, J. T., & Silva, A. J. (2014). Encoding and storage of spatial information in the retrosplenial cortex. Proceedings of the National Academy of Sciences of the United States of America, 111(23), 8661–8666. https://doi.org/10.1073/pnas.1313222111