Seizures Reprogram Cerebellar Purkinje Neurons: A Multivariate Electrophysiological Classification Reveals Hidden Subtypes.

Purkinje neurons (PNs), the sole output neurons of the cerebellar cortex, control motor activity, cortical excitability, and seizure propagation. They regulate cerebello-thalamo-cortical circuits by inhibiting deep cerebellar nuclei, which are increasingly linked to epilepsy. While epilepsy-related alterations in cortical and hippocampal neurons are well documented, cerebellar PNs remain understudied. Disruption of PN-mediated inhibition may lead to a breakdown in network regulation and promote seizure activity. This study investigated whether prolonged epileptic activity alters both passive and active electrophysiological properties of PNs and whether multivariate analysis can reveal biophysical abnormalities associated with epilepsy. Additionally, we explored whether spectral EEG dynamics reflect or predict these cellular changes. Whole-cell patch-clamp recordings were obtained from Crus II PNs in amygdala-kindled rats to extract 12 intrinsic membrane properties. Multivariate analysis, utilizing principal component analysis (PCA) and K-means clustering, identified latent electrophysiological subtypes. Concurrent EEG signals from the hippocampus and amygdala were analyzed using Fast Fourier Transformation (FFT), PCA, and supervised classification to track seizure-related spectral dynamics. Results revealed that chronic seizures reduce PN excitability and induce a convergence toward specific biophysical states. EEG analysis uncovered latent spectral patterns associated with behavioral seizure severity. A Random Forest Classifier trained on spectral band power predicted Racine stages reasonably, highlighting Beta and Gamma bands being particularly influential. These findings demonstrate that chronic seizures drive coordinated changes in the properties of cerebellar neurons and EEG dynamics. This multiscale approach reveals consistent electrophysiological changes at cellular and network levels, underscoring the cerebellum’s role in epileptogenesis and supporting its potential as a therapeutic target.