Delayed auditory encoding and variable representation of stimulus regularity in cerebellar lesion patients

The dynamic and fleeting nature of sound necessitates the rapid encoding and use of information distributed over time. Here we investigated cerebellar contributions to these abilities. We measured EEG from cerebellar patients and healthy controls while they listened to "oddball" sound sequences consisting of infrequent pitch-deviant and frequent standard tones. Inter-stimulus-intervals were temporally regular (600 ms) or irregular (200-1000 ms). This allowed probing early event-related potentials (ERP; P50, N100) that reflect repetitive and changing stimulus characteristics in temporally regular or less (irregular) predictable sequences. Further, time-frequency data provided an index of temporal processing variability at the stimulation frequencies. We expected that cerebellar lesions lead to aberrant encoding and use of auditory information, reflected in the ERP morphology of peak amplitudes, latencies and typical suppression effects linked to stimulus predictability. Results confirm longer P50 peak latencies in patients and variable processing at stimulation frequencies covarying with the location of cerebellar damage. These findings further support the idea that the cerebellum might play a generalizable role in the encoding of auditory stimulation over time.