Lesion of the Fastigial Nucleus in Juvenile Rats Deteriorates Rat Behavior in Adulthood, Accompanied by Altered Neuronal Activity in the Medial Prefrontal Cortex.

The cerebellar cognitive affective syndrome may result from various cerebellar injuries. Although it is not exactly known which anatomical structures are involved, the fastigial nucleus has been thought to play a pivotal role according to recent studies. Here we investigate whether bilateral fastigial nucleus lesions in juvenile rats affect cognitive-associative and limbic related functions in adulthood. Furthermore, potential effects on the neuronal activity in the medial prefrontal cortex (mPFC) and local field coherence with the sensorimotor cortex (SMCtx) were evaluated. The fastigial nucleus was lesioned bilaterally by thermocoagulation via stereotaxically inserted electrodes in 23-day old male Sprague Dawley rats. Naïve and sham-lesioned rats (electrodes inserted above the nucleus and no electrical current applied) served as controls. As adults, all groups were tested for cognitive-associative function, social behavior, and anxiety. Thereafter, electrophysiological recordings were obtained under urethane anesthesia. Finally, lesions and recording sites were histologically verified. Spatial learning in a radial maze test and learning in an operant learning paradigm was disturbed in rats with fastigial lesions. Furthermore, in the elevated plus maze anxiety was enhanced, whereas social behavior was not affected. Electrophysiological recordings showed enhanced local field coherence between mPFC and SMCtx across all frequency bands. Impaired cognitive and affective functions together with enhanced coherence between mPFC and SMCtx after bilateral fastigial nucleus lesions indicate that the fastigial nucleus contribute to the development of the cerebellar cognitive affective syndrome and associated motor behavior.