Neuroscience 2009 location:Chicago, USA date:17 - 21 October 2009
Striatum and hippocampus are critically involved in visuo-spatial learning processes. The level of contribution from each of these structures varies depending on the phase of learning. Comparing changes in search strategy over the course of learning and determining areas of brain activation will provide more insight into the specific differential and time dependent contributions of these structures. Mice were trained in the Morris water maze task for either 3 days (early learning phase group) or 30 days (late learning phase group) and culled for IEG expression profiling 45 min after finishing the task. Behavioral analysis revealed a significant decrease in the average search distance to the platform in the late phase of training when compared to the early phase. An improvement in the directional error of the initial trajectory
towards the platform was observed in the late learning phase. Neuronal activity at the different phases of spatial learning was determined by a comparison of expression level of the immediate early gene homer1a in hippocampus between different mouse groups (trained and control animals). We found an overall higher activity of the hippocampus during the early learning phase compared to the late phase. Within the hippocampus, expression differences between the different areas were also observed. The mouse search strategy data were directly compared to strategies used by human subjects that were trained in a virtual Morris water maze task. We also will compare these results with acquisition curves and search strategies of hippocampal and
striatal lesioned animals (at different time points). Comparison of all these data allows us to cross-validate learning related plasticity between mouse and man.