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. 2005 Oct 12;25(41):9384–9397. doi: 10.1523/JNEUROSCI.0832-05.2005

Figure 9.

Figure 9.

Diagrams summarize changes in topography and magnitude of learning-specific Arc mRNA levels in the entorhinal-hippocampal circuitry during recall of recent and 1-month-old water-maze memories. A, During 1 month in memory retention, task-specific DG activity, widely and evenly distributed across the multiple 400 μm segments, has become limited to a few scattered segments. A weak signal could be identified as learning specific in the rest of the DG segments only if they were combined. B, The multiple CA1 segments were specifically activated by recent memory retrieval, whereas only one dHC segment displayed task-specific activity during a long-term memory task. The ventral CA1 displayed a higher signal compared with the dHC, similar to the ventral subiculum (D) during recent recall. C-E, CA3, subiculum, and the entorhinal cortex displayed the most persistent learning-specific signals after both recent and remote memories recall in contrast to DG and CA1; however, signal representation and magnitude have changed. C, In CA3, a weaker signal has been shifted toward the dorsal pole. The CA3 signal did not change in the ventral HC, where it could be identified only in the combined segments. D, In the subiculum, the signal occupied mostly the same regions of the dHC and vHC, but it had a significantly reduced magnitude in the vHC over a 1 month retention. E, Although both MEA and caudal LEA were consistently activated by the navigation task, rostral LEA was specifically activated after performance on a recent memory task. Note that there was no specific activity at the dorsal and ventral HC poles, and there were two sectors of specific activity in the central parts of the dHC and vHC separated by segments without it. Statistically significant differences in mean values of signal magnitude in individual segments were coded through their intensity in a gray scale. Data for the diagrams were pooled from supplemental Tables 1-4 (available at www.jneurosci.org as supplemental material) and Figures 3, 6, and 7. For some regions (dorsoventral CA3 and ventral DG), the learning-specific signal could be identified as statistically significant only if the segments were analyzed in combination. DGdb, DG dorsal blade; mo, month; hr, hour.