FIGURE 1.

(A) We used two-photon microscopy to examine Ca²⁺ influx induced by action potentials (APs) in layer II cortical pyramidal neurons (CPNs) from R6/2 model mice. (A1) A CPN was patched and filled with a Ca²⁺ indicator (OGB-1). (A2) Action potentials (APs) evoked by 50 ms depolarizing current steps from the resting membrane potential. Accompanying Ca²⁺ transients are shown above the APs. (A3) The amplitude of somatic Ca²⁺ transients was reduced in R6/2 mice compared to controls. This reduction was compensated by increased decay times, which could lead to reduced Ca²⁺ buffering capacity [modified from Oikonomou et al. (2021)]. (B) A miniscope and a video camera above a cylindrical arena were used to visualize Ca²⁺ transient activity and behavior of WT and R6/2 mice. (B1) Movement tracking during 5 min behavior video recording. Notice the sparsity of movement in the symptomatic R6/2 mouse. (B2) Images of fluorescent CPNs in layer V of the same WT and symptomatic R6/2 mice. (B3) Ca²⁺ transients from three selected CPNs shown in B2. *p < 0.05, **p < 0.01, and black diamonds are outliers for the box and whisker plots.