STN DBS in PD: Effect of Associative vs. Sensorimotor Stimulation On Executive Function Kalyn Horst, B.S.*, Laura Manning, M.S. , Edward Golob, Ph.D. , and Erich Richter, M.D.* *Department of Neurosurgery, LSU Health Sciences Center, New Orleans, LA Department of Psychology, Tulane University, New Orleans, LA Background DBS of the STN is a common treatment for intermediate stage Parkinson’s disease patients Effective for motor symptoms Tremor Rigidity Bradykinesia May impair cognition, particularly executive function1 Rationale for Current Study Hamani, et al. The subthalamic nucleus in the context of movement disorders. Brain, 2004. 127: p. 4-20. Hypothesis: cognitive deficits appearing after DBS are due to the stimulation of the ventral region of the STN Methodology: Patient Population & Measure Design Two auditory conflict tasks5,6 using E-Prime software Seven subjects (male=6, female=1, aged 46-74) and four controls (male=2, female=2, aged 21-30) have participated to date Methodology: Tasks Used Stimulus Response Compatibility (SRC) Simon Effect (SE) Stimulus information Spatial arrangement only Spatial arrangement, amplitude modulation Response(s) Two types of response: Ipsilateral and contralateral One type of response only (amplitude modulation) Measures Motor function Cognitive function Preliminary Results Motor Function Task: Baseline Performance 1200 Control (Contra) Study (Ipsi) 1100 Median Reaction Time (ms) Control (Ipsi) Study (Contra) 1000 900 800 700 600 500 400 Far Left Left Right Stimulus Location Far Right Median Reaction Time (ms) Median Reaction Time (ms) 1200 1200 Motor Function Task: Task: Motor Motor Function Function Task: BaselineBaseline vs. Ventral Dorsal Region Region Stimulation Stimulation 1100 1100 1000 1000 Ventral(Ipsi) Dorsal (Ipsi) Baseline (Ipsi) Dorsal (Contra) Ventral (Contra) 900900 Baseline (Ipsi) Baseline (Contra) Baseline (Contra) 800800 700700 600600 500500 400400 Left FarFar Left Left Left Right Right Stimulus Location Stimulus Location Right FarFar Right Motor Function Task Trends PD population has greater reaction times as compared to a healthy population Stimulation of dorsal region did not yield substantially different SRC task performances Stimulation of ventral region did not yield substantially different SRC task performances Cognitive Function Task: Baseline Performance 1200 Control (Left) Control (Right) Study (Left) Median Reaction Time (ms) 1100 Study (Right) 1000 900 800 700 600 500 Far Left Left Right Stimulus Location Far Right Cognitive Function Task: Task: Cognitive Function Cognitive FunctionTask: Dorsal Region BaselineBaseline vs. Ventral Region Stimulation Stimulation Median Reaction Time (ms) 1200 Dorsal (Left) Ventral (Left) Baseline (Left) 1100 Dorsal (Right) Ventral (Right) 1000 Baseline (Left) (Left) Baseline Baseline (Right) Baseline (Right) (Right) Baseline 900 800 700 600 500 400 Far Left Left Right Stimulus Location Far Right Cognitive Function Task Trends PD population has greater reaction times as compared to a healthy population Stimulation of dorsal region yielded improved reaction times Stimulation of ventral region worsened reaction times when compared to baseline Preliminary Results Summarized Performances on the motor conflict task were not substantially affected by stimulation in either the dorsal or ventral region Performances on the cognitive conflict task improved with stimulation of dorsal region but worsened with ventral region stimulation Discussion Cognitive decline, particularly in executive function, is often observed following STN DBS in PD patients. For this target type of DBS, both dorsal and ventral regions are stimulated. Hypothesis: cognitive decline results from the ventral region stimulation Thus far, data suggest dorsal stimulation of the STN is beneficial to patients’ PD symptoms whereas ventral stimulation actually impairs executive function Limitations & Future Directions A larger patient population is needed to gain statistical power Development of visual and tactile complementary tasks References 1. 2. 3. 4. 5. 6. Smeding, H.M., et al., Neuropsychological effects of bilateral STN stimulation in Parkinson disease: a controlled study. Neurology, 2006. 66(12): p. 1830-6. Yelnik, J., Modeling the organization of the basal ganglia. Rev Neurol (Paris), 2008. 164: 969-976 Obeso, J.A., et al., The origin of motor fluctuations in Parkinson's disease: importance of dopaminergic innervation and basal ganglia circuits. Neurology, 2004. 62(1 Suppl 1): p. S17-30. Amick, M.M. and J. 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