Introduction The impact of Deep Brain Stimulation (DBS) on cognitive and language abilities of individuals with Parkinson’s disease (PD) is not established. Moreover, the research that has been conducted so far on language abilities in PD has focused primarily on English. There have been claims in the literature (Hochstadt 2009) that performance on center embedded relative clauses, if falling behind in PD, is a result of impaired executive functions and, in particular, of set shifting (rather than of impaired grammatical knowledge). Such a claim needs confirmation. PD individuals subject to DBS provide a good opportunity to do so, on the basis of the direction of change on language and cognitive performance after the operation. Another area of grammar that has been found impaired in PD is past Tense formation of regular verbs, a result of impaired grammatical rule application (Ullman et al et seq.). Research on this topic has been mainly conducted on English, a morphologically Impoverished language. In a study of Greek-speaking PD individuals, Terzi et al. (2005) found that they performed 90% accurately. The effects of DBS in such a morphologically rich language are not known, by contrast to English, for which it was recently found that DBS affects negatively past Tense formation of regular verbs (Phillips et al. 2012). Against the above background, this study investigates the following interrelated issues: 1. the impact of DBS on cognitive and linguistic abilities of PD individuals; 2. whether comprehension of relative clauses is related to executive functions; 3. whether past Tense formation is affected by DBS. This is the first report on an ongoing study of the linguistic and cognitive abilities of Greek- speaking PD individuals, before and after DBS. The effect of Deep Brain Stimulation on language and cognitive abilities of Greek-speaking individuals with Parkinson's disease 1 A. Terzi, 2 V. Fyndanis, 1 E. Barampati, 3 C. Constantoyannis, 3 I. Ellul 1 Technological Educational Institute of W. Greece, Patras, 2 Univ. of Potsdam, 3 Univ. of Patras P1’s % correct performance P2’s % correct performance Methodology Participants Three PD individuals have taken part in the study so far (all male, age range: 60-66). Participants were tested a) during the two days preceding the operation, and b) three months after the operation, on the tasks below. Tasks Cognitive tasks 1. Digit forward span task (verbal short-term memory) 2. Digit ordering task (verbal working memory) 3. Plus-minus task (set-shifting) 4. Stroop task (inhibition) Language tasks 1. Sentence-picture matching task (comprehension of relative clauses) 96 relative clauses––power point presentation––each sentence was accompanied by a slide with 4 pictures from which the participant had to choose the one matching the sentence they heard. Four types of relative clauses: a. right-branching active (N=24) The cook follows the sailor who is tall. b. center-embedded active (N=24) The cook who follows the sailor is tall. c. right-branching passive (N=24) The cook is followed by the sailor who is tall. d. center-embedded passive (N=24) The cook who is followed by the tailor is tall. 2. Sentence completion task (production of past-reference verb forms). 18 sentences/real regular verbs Participants heard a sentence that contained a verb and were instructed to complete a following sentence with the same verb in the past tense, e.g.: The boy opens the window. > Yesterday, suddenly, the boy ___ the window. (Target): opened References 1. Hochstadt, J. (2009) Set-shifting and the on-line processing of relative clauses in Parkinson’s disease: Results from a novel eye-tracking method. Cortex 45: Phillips, L., K. Litcofsky, M. Pelster, M. Gelfald, M.T. Ullman, & P.D. Charles (2012) Subthalamic Nuvleus Deep Brain Stimulation Impacts Language in Early Parkinson’s Disease. PloS One 7: e Terzi, A, S. Papapetropoulos, & E. D. Kouvelas (2005) Past tense formation and comprehension of passives sentences in Parkinson’s disease: Evidence from Greek. Brain and Language 94: Ullman, M., S. Corkin, M. Coppola, G. Hickok, J.H. Growdon, W. Koroshetz, & S. Pinker (1997) A neural dissociation within language: Evidence that the mental dictionary is part of declarative memory, and that grammatical rules are processed by the procedural system. Journal of Cognitive Neuroscience 9: Results This research has been co-financed by the European Union (European Social Fund - ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program: ARCHIMEDES III. Investing in knowledge society through the European Social Fund. P3’s % correct performance Summary of results & Discussion After DBS, all three PD participants performed significantly better on the stroop task (which tapped inhibition). The impact of DBS on short-term memory and set-shifting is not clear, as results are mixed. After DBS, working memory was improved in all three participants, but the difference was not significant. Only one of the three PD participants, P3, benefited from DBS on relative clauses, with statistically significant improvement on the passive right-branching. DBS seems to enhance PD individuals’ inhibition and WM capacity, which may lead to improvement in language performance when the linguistic task involves syntactic complexity (of the type involved in the relative clauses). Past Tense formation remained invariant (contrary to Phillips et al. 2012, for English). These preliminary results suggest that DBS does not affect cognitive functions and language abilities in opposite directions, neither does it affect rule application negatively in a morphologically rich language such as Greek. RB act: Right-branching relative clauses CE act: Center-embedded relative clauses RB pas: Right-branching passive clauses CE pas: Center-embedded passive clauses Past T: Past Tense STM: Short Term Memory WM: (verbal) Working Memory SS: Set-Shifting Inhib: Inhibition Note: In SS & Inhib, the lower the percentage the higher the performance Contact Info: