This research project aims to directly register within the thalamus, globus pallidus interna (Gpi) and subthalamic nucleus (STN) to what extent these nuclei are involved in grammatical comprehension. Thirty right- handed Deep Brain Stimulation (DBS) patients, divided into three groups (DBS thalamus, GPi and STN) will be included in the study. During EEG registration, the subjects will be asked to judge word-class information, subject-verb agreement, word order and thematic role assignment. Source and coherence analyses of the event related potentials will enhance our fundamental insight in cortico-subcortical grammatical interaction. The results will allow to construct a neurolinguistic model on the subcortical organization of grammatical comprehension.