Natividad Ybarra

My name is Natividad Ybarra and I am a third year doctoral student in Dr. Brenda Claiborne’s laboratory.  My research interests reside in the neural architecture of hippocampal CA1 pyramidal neurons in aged transgenic male mice expressing GFP.  With these animals I am able to obtain the spine densities (indicators of excitatory synaptic input) in all three laminae of the cornu ammonis (stratum lacunosum-moleculare, stratum radiatum, and stratum oriens) as well as the total dendritic lengths of these cells. Recently I have found that spine densities of CA1 pyramidal neurons decrease significantly with age in a laminar specific manner.  My preliminary data suggest that the spine densities on dendrites with afferents from the CA3 Shaffer collaterals (distal basal dendrites within the stratum oriens and secondary apical dendrites of the stratum radiatum) decrease by approximately 10% at 24 months of age as compared to 6, 12, and 18 months of age.  In contrast, my preliminary data also suggest that spine densities on distal apical dendrites in the stratum lacunosum-moleculare (afferents from the entorhinal cortex) significantly decrease by 17% at 18 and 24 months of age as compared to 6 and 12 month age groups.  Currently I am in the process of reconstructing the dendritic trees of the same neurons at each age group.  Below are examples of the cells I have reconstructed for 6 and 24-month-old male mice (scale bar = 100µm).


6 month

24 month