Enhanced adolescent learning and hippocampal axonal projections following preadolescent spatial exposure to a water or dry maze

Structural Development of Hippocampal CA3 Pyramidal Neurons and Relation to the Development of Spatial Learning and Memory in Rats

“…Results showed that experiencing water maze or a dry maze thorough the preadolescent period led to improved spatial performance on the water maze during adolescent period. This was correlated with rearrangements found in the axonal inputs received in CA3 area (Wartman, et al, 2012).…”

“…Converging lines of evidence from behavioral studies point to the postnatal period from p16 to p24 as a sensitive developmental timeframe for spatial behavioral function to emerge. Improved performance on a number of spatial tasks during this timeframe has been noted (Akers, Candelaria-Cook, Rice, Johnson, & Hamilton, 2009, 2011Akers, Candelaria, & Hamilton, 2007;Blair et al, 2013;Brown & Whishaw, 2000;Douglas, Peterson, & Douglas, 1973;Dumas, 2004;Green & Stanton, 1989;Holahan, Honegger, & Routtenberg, 2007;Jablonski, Schiffino, & Stanton, 2012;Keeley, Wartman, Haeusler, & Holahan, 2010;Langston et al, 2010;Rudy, 1993;Rudy & Morledge, 1994;Rudy, Stadler-Morris, & Albert, 1987;Smith, Macdonald, & Holahan, 2011;Tonkiss, Shultz, & Galler, 1992;Wartman et al, 2012;Wills, Cacucci, Burgess, & O'Keefe, 2010) indicating a sensitive developmental period for spatial behavior to emerge between p16 and p24. The present anatomical results suggest that maturation of thorny excrescences on CA3 neurons may contribute to the developmental emergence of spatial behavioral function.…”

“…For example, rats were used to investigate if preadolescent exposure to water maze or a dry maze task could result in improvement in the performance on water maze and alternations in hippocampal connections (Wartman, et al, 2012). Results showed that experiencing water maze or a dry maze thorough the preadolescent period led to improved spatial performance on the water maze during adolescent period.…”

The Acquisition and Expression of Remote Spatial Memories Formed During the Juvenile Period are Impaired by AMPAr Blockade

“…This hippocampal remodeling has also coincided with improved performance on cognitive tasks. Moderate improvements in spatial memory were observed in rats that were assessed in a Morris water maze task between p16 and p19, while dramatic improvements in water maze performance, similar to those seen in adults, were observed in rats assessed between p18 and p21 (Holahan et al, 2006;Keeley et al, 2010;Wartman et al, 2012). It can then be inferred that pharmacological insults administered during the sensitive developmental period may disrupt the remodeling process, thus impairing the subsequent spatial memory enhancements that may come as a result.…”

“…There is evidence that synaptic connections within the hippocampus that mediate spatial learning and memory undergo remodeling between p18 and p24 (Wartman et al, 2012). Holahan et al (2006) observed increased mossy fiber projections to the stratum lucidum during p18 and p21, which continued to grow, and eventually proliferated into the CA3 pyramidal layer and terminated at the dorsal stratum oriens by p24.…”