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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
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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 impaircognition, 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
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 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 • 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. Grace, Deep brain stimulation surgery for Parkinson's disease: the role of neuropsychological assessment. Med Health R I, 2006. 89(4): p. 130-3. • De Jong, R., C.C. Liang, and E. Lauber, Conditional and unconditional automaticity: a dual-process model of effects of spatial stimulus-response correspondence. J Exp Psychol Hum Percept Perform, 1994. 20(4): p. 731-50. • Kornblum, S., T. Hasbroucq, and A. Osman, Dimensional overlap: cognitive basis for stimulus-response compatibility--a model and taxonomy. Psychol Rev, 1990. 97(2): p. 253-70.