Neuroplasticity of emotional processing in cerebellar lesions as evidenced by event-related potentials

Background: Recent neuroimaging studies provided consistent evidence for an engagement of cerebellar modules in affective and attentional processes instead of being exclusively higher supratentorial functions. Here, we report on a sixty-three year old man suffering from a cardioembolic infarction of the right-hemispheric cerebellum. Beyond a hemiataxia he presented with severe cognitive deficits and affective symptoms (lowered personal distance, diminished impulsive control). Visual event-related potential (ERP) results from this patient initially indicated disturbances of attention-dependent early processing within the temporooccipital cortex as well as higher-order processing within the parietocentral cortex, thus pointing to altered selective encoding. These stages are probably related to top-down-controlling systems of frontal structures. We studied the patient again after two years in order to investigate the neuronal plasticity of functional cerebro-cerebellar structures. We expected a shift of the peak amplitudes of the late positive potentials (LPPs) to centroparietal topografies.

Methods: During the electroencephalography (EEG) session we presented pictures of the International Affective Picture System (IAPS) having a different affective valence and inducing a different arousal. For evaluation of the Early Posterior Negativity (EPN) over temporooccipital areas we conducted three trials, each containing 702 images of the IAPS (displayed continuously; 3Hz/image) during one implicit (primary emotional task) or two explicit (secondary cognitive task) task instructions, respectively. For capturing the LPPs, 699 images of the IAPS were presented (1Hz/image).

Results: Pictures with a highly affective content were associated with augmented ERPs in all trials. In all trials, we observed a temporooccipital EPN as well as a parietal LPP. The significant lowering of the EPN in the visual explicit condition improved between the two measurements. Comparing the initial measurement and the measurement after two years the LPP yielded a maximum over centroparietal sites in opposite to frontocentral areas.

Conclusions: In two ERP-components post-stroke changes that are possibly due to neuroplasticity were revealed. Our results may confirm the cerebellar involvement in supratentorial networks of affective modulation and encourage conducting further research on this topic. ERPs are a promising way to investigate cerebellar components and its neuroplasticity.