Fig. 5.

Heterogenous firing patterns of Purkinje cells that had or had not fused with BM-derived cells in EAE mice. a–c Different spontaneous firing patterns recorded from three Purkinje cells that had not fused with BM-derived cells, identified by lack of EGFP-expression. Extracellular recordings were made from Purkinje cells located in cerebellar slices ex vivo. Dissimilar patterns of firing were recognized according to criteria established for Purkinje cells from control animals (see Online Resource 1; Fig. S1). a Tonic firing in a regular pattern; IF frequency is constant (left upper) during a 40 s period of extracellular recording (left lower). The regular firing is visible in the expanded 1 s fragment of the current trace (middle, indicated by filled circle) and the narrow histogram (CV) of ISI with a single peak (right, the distribution was derived from 6 min of recording). b Trimodal firing; three firing modes (quiet, tonic and bursting) are evident in the plot of IF against time (left upper) and the continuous extracellular recording (left lower). Tonic and burst firing is evident in the expanded 1 s fragments of current traces (middle) and the multiple components and relatively high CV of the ISI histogram (right, generated for a single firing episode). c Irregular firing; in this cell, episodes of firing are separated by distinct quiet periods. IF fluctuates widely (left), the expanded current trace reveals the occurrence of spikes in clusters (middle) and the histogram of ISI during a firing episode (right) reveals extremely short and longer ISI within and between clusters of spikes. d–f Different spontaneous firing patterns recorded in three Purkinje cells that had fused with BM-derived cells, identified by EGFP-fluorescence. The images show a fluorescent cell identified with an epifluorescence microscope in an unfixed cerebellar slice (left) prior to recording from the soma with an extracellular recording pipette (right). Examples of cells firing d tonically, e trimodally and f irregularly, identified by the same criteria applied to EGFP-negative cells and cells from control animals