Research Project
10194940
The higher order dorsolateral prefrontal cortex (LPFC) and the limbic anterior cingulate cortex (ACC) are key areas in the frontal neural network that mediates executive cognitive functions, which often decline during normal aging. There is strong evidence that layer 3 (L3) pyramidal cells in these higher-order areas are selectively vulnerable during normal aging in the primate, especially compared to those in sensory cortices such as the primary visual cortex (V1). Indeed, extensive morphologic, electrophysiological and structural age-related changes are present in LPFC but not V1 L3 pyramidal cells in the rhesus monkey. However, the mechanisms underlying these area-specific vulnerabilities, and whether LPFC and ACC exhibit similar vulnerability to aging, is not known. The overall hypothesis of this proposal is that LPFC and ACC L3 pyramidal cells share transcriptomic and phenotypic profiles that are highly distinct from V1 neurons, and that underlie selective vulnerability of these frontal areas to age-related synaptic dysfunction and hyperexcitability. The cognitive status of young and aged rhesus monkeys will be assessed on a battery of behavioral as part of other projects. Single-cell Patch-Seq transcriptomic assessment of physiologically characterized L3 pyramidal cells in acute slices of LPFC, ACC and V1 prepared from these monkeys will then be performed. Transcriptomic findings will be validated with RNAscope in situ hybridization and immunohistochemical assessment of proteins on/in biocytin filled, morphologically characterized neurons. This project has two aims: 1) assessment of the transcriptomic profiles of physiologically-characterized pyramidal cells in young vs. aged LPFC, ACC and V1. We will use whole-cell patch-clamp recordings to quantify over 30 physiological variables in L3 pyramidal cells and then harvest these cells for Patch-Seq to determine their transcriptomic profiles. 2) assessment of the morphology and protein expression of pyramidal cells in young vs. aged LPFC, ACC and V1. We will characterize protein expression on a separate subset of non-harvested but biocytin-filled morphologically characterized cells and thus validate Aim 1 gene expression findings. Data on specific age-related genetic changes in expression of ion channels and synaptic markers in individual L3 neurons will be related to age-related changes in genes for oxidative stress, inflammation, and neurodegeneration such as caspase 3 and TNF?. The project will reveal mechanisms underlying differential age-related neuronal dysfunction and mechanisms that can compensate for changes to restore cellular function, and thus has broad implications for therapeutic strategies to reduce cognitive decline during normal aging. This study will form the basis of future studies to investigate relationships and co-dependence of age-related cellular changes in a variety of cell types, laminae and cortical areas during aging that can be correlated with cognitive performance in rhesus monkeys.
