The significant differences were observed only in the suprapyramidal blade, but not in the infrapyramidal blade. In the dentate gyrus (DG), the NDs of granule cells were significantly higher at the dorsal level (916.7 × 103/mm3) than at the ventral level (788.9 × 103/mm3). In the CA3 region, there were no significant differences in the NDs along the dorsoventral and transverse axes (dorsal, 165.2 × 103/mm3 ventral, 172.4 × 103/mm3). An EF‐hand calcium‐binding protein, calbindin D28K, was expressed in ∼45% of CA1 pyramidal neurons both at the dorsal and ventral level. In the CA1 region, the NDs of CA1 pyramidal neurons were almost three times higher at the dorsal level (447.5 × 103/mm3) than at the ventral level (180.5 × 103/mm3) meanwhile, along the transverse axis, the NDs were significantly higher in the proximal portion than in the distal portion both at the dorsal and ventral levels. Here, we stereologically estimated the numerical densities (NDs) of glutamatergic principal neurons in the mouse hippocampus and encountered the significant differences along the dorsoventral axis.
A rigorous quantitative analysis concerning lamellar cytoarchitecture would be important for promoting further research on the regional differentiation of the hippocampus. Recent studies have emphasized functional dissociations between dorsal and ventral hippocampus in learning, emotion, and affect. Our results demonstrate that processes of aging impact brain structures and associated behaviors differentially, with cerebellum showing earlier senescence than hippocampus.Stereological estimation of numerical densities of glutamatergic principal neurons in the mouse hippocampus Stereological estimation of numerical densities of glutamatergic principal neurons in the mouse. Slice electrophysiology recorded from an additional 48 CBA mice indicated significant deficits in LTD appearing in cerebellum between 4 and 8 months, whereas 4- to 12-month mice demonstrated similar hippocampal LTD and LTP values. Stereology indicated significant loss of Purkinje neurons in the 18- and 24-month groups, whereas pyramidal neuron numbers were stable across age. These same CBA mice showed no significant differences in contextual or cued fear conditioning. Forty-four CBA mice tested at one of five ages (4, 8, 12, 18, or 24 months) demonstrated statistically significant age differences in cerebellum-dependent delay eyeblink conditioning, with 24-month mice showing impairment in comparison with younger mice. Several forms of synaptic plasticity were assessed at different ages in CBA mice: long-term depression (LTD) in both cerebellum and hippocampus and NMDA-mediated long-term potentiation (LTP) and voltage-dependent calcium channel LTP in hippocampus. In a subset of the behaviorally tested mice, we used unbiased stereology to estimate the total number of Purkinje neurons in cerebellar cortex and pyramidal neurons in the hippocampus.
Our aim was to compare cerebellum-dependent delay eyeblink classical conditioning and hippocampus-dependent contextual fear conditioning in the same animals using the same conditioned and unconditioned stimuli for eyeblink and fear conditioning.
We examined learning over the adult life span in CBA mice, along with morphological and electrophysiological substrates. Cognitive functions show many alternative outcomes and great individual variation during normal aging.
0 kommentar(er)
