behavior/neurological
• on a fixed speed rotarod test, motor deficits gradually increased with age, with no difference in time spend on the rod at 3 months of age, slightly less time at 6 months and significantly less time at one year of age compared to wild-type, although performance improved after repeated training
• on an accelerating rotarod test, 3-4 week old mutants did not show a difference in performance compared to wild-type while at 4 months of age, mutants remained on the rod for a significantly shorter time, however performance was improved and reached the wild-type level after repeat testing
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nervous system
• thickness of the internal granule layer was significantly reduced at P21, P28 and in adult mutants
• granule cell density was markedly reduced between P10 and P28 compared to wild-type and Grin2c null mice, indicating that reduction is due to Grin2b overexpression and not due to lack of Grin2c
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• the number of synapses between excitatory fibers and Purkinje cell dendritic spines in the molecular layer was reduced by about one third in adult mutants
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• the molecular layer was significantly reduced at P10 and this difference persisted until adulthood
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