Transient inhibition of the cerebellum impairs change-detection processes: Cerebellar contributions to sensorimotor integration

Patients with cerebellar lesions have shown altered responses to unpredictable stimuli. This finding has led to the belief that the cerebellum is involved in comparing incoming stimuli with previously experienced stimuli in order to predict and coordinate responses. The role of the cerebellum is thought to extend beyond motor control to higher-order executive functions, which allow for the evaluation of stimuli that influence our personal reactions, emotions, and thoughts. This current study tested the role of the cerebellum on cognitive function by examining incoming sensory stimuli being unattended by the participant. Median and ulnar nerve somatosensory evoked potentials (SEPs) were elicited by electrical stimulation via surface electrodes. Nerve stimulation was presented in an oddball fashion where median and ulnar stimulation were presented as frequent and deviant stimuli, respectively. Electroencephalography (EEG) was used to measure participants' cortical responses both before and after either continuous theta burst stimulation (cTBS) used to transiently inhibit cerebellar activity, or a sham condition. The N140 was shown to be modulated in response to deviant stimuli, resulting in a large negativity pre-cTBS, referred to as the mismatch-negativity (MMN). Following cTBS, the MMN was reduced, resulting in similar waveform patterns in response to both the frequent and deviant stimuli. The mechanisms that are thought to modulate this change within the N140 in response to deviant stimuli are believed to be different from those that govern its response to frequent stimuli. The cerebellum may be involved in attentive change-detection processes that are critical for a wide-range of everyday processes.