Inability to Process Negative Emotions in Cerebellar Damage: a Functional Transcranial Doppler Sonographic Study

Recent studies have implicated the cerebellum as part of a circuitry that is necessary to modulate higher order and behaviorally relevant information in emotional domains. However, little is known about the relationship between the cerebellum and emotional processing. This study examined cerebellar function specifically in the processing of negative emotions. Transcranial Doppler ultrasonography was performed to detect selective changes in middle cerebral artery flow velocity during emotional stimulation in patients affected by focal or degenerative cerebellar lesions and in matched healthy subjects. Changes in flow velocity during non-emotional (motor and cognitive tasks) and emotional (relaxing and negative stimuli) conditions were recorded. In the present study, we found that during negative emotional task, the hemodynamic pattern of the cerebellar patients was significantly different to that of controls. Indeed, whereas relaxing stimuli did not elicit an increase in mean flow velocity in any group, negative stimuli increased the mean flow velocity in the right compared with left middle cerebral artery only in the control group. The patterns by which mean flow velocity increased during the motor and cognitive tasks were similar within patients and controls. These findings support that the cerebellum is part of a network that gives meaning to external stimuli, and this particular involvement in processing negative emotional stimuli corroborates earlier phylogenetic hypotheses, for which the cerebellum is part of an older circuit in which negative emotions are crucial for survival and prepare the organism for rapid defense.