a-c, Whole-cell recording from reprogrammed MSNs from three independent longitudinal groups (individual I (a); II (b); III (c)) co-cultured with human astrocytes showing the inward/outward currents and multiple action potentials (APs). d, RT-qPCR analysis of DARPP-32 expression in longitudinally aged MSNs (n = 6, ****p < 0.0001, The sample size (n) corresponds to the number of biologically independent samples). Statistical significance was determined using two-tailed unpaired t-test and mean±s.e.m. e and f, Heatmap of Differentially Expressed Genes (DEGs) in fibroblasts (e) and MSNs (f) (FDR < 0.05, | FC | ≥ 1.5). g, Venn diagram of the genes enriched in calcium signaling pathway from old HD-MSNs.