title: Striatal and thalamic GABA level concentrations play differential roles for the modulation of response selection processes by proprioceptive information.
abstract: The selection of appropriate responses is a complex endeavor requiring the integration of many different sources of information in fronto-striatal-thalamic circuits. An often neglected but relevant piece of information is provided by proprioceptive inputs about the current position of our limbs. This study examines the importance of striatal and thalamic GABA levels in these processes using GABA-edited magnetic resonance spectroscopy (GABA-MRS) and a Simon task featuring proprioception-induced interference in healthy subjects. As a possible model of deficits in the processing of proprioceptive information, we also included Parkinson's disease (PD) patients in this study. The results show that proprioceptive information about unusual postures complicates response selection processes in controls, but not in PD patients. The well-known deficits of PD patients in processing proprioceptive information can turn into a benefit when altered proprioceptive information would normally complicate response selection processes. Striatal and thalamic GABA levels play dissociable roles in the modulation of response selection processes by proprioceptive information: Striatal GABA levels seem to be important for the general speed of responding, most likely because striatal GABA promotes response selection. In contrast, the modulation of response conflict by proprioceptive information is closely related to thalamic GABA concentrations with higher concentration being related to a smaller response conflict effect. The most likely explanation for this finding is that the thalamus is involved in the integration of sensorimotor, attentional, and cognitive information for the purpose of response formation. Yet, this effect in the thalamus vanishes when controls and PD patients were analyzed separately.
authors.affiliation: School of Health Sciences, Purdue University, West Lafayette, IN, USA; Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: Shalmali
authors.initials: S
authors.lastname: Dharmadhikari
authors.affiliation: School of Health Sciences, Purdue University, West Lafayette, IN, USA; Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: Ruoyun
authors.initials: R
authors.lastname: Ma
authors.affiliation: School of Health Sciences, Purdue University, West Lafayette, IN, USA; Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: Chien-Lin
authors.initials: CL
authors.lastname: Yeh
authors.affiliation: Cognitive Neurophysiology, Department of Child and Adolescent Psychiatry, Faculty of Medicine of the TU Dresden, Germany.
authors.forename: Ann-Kathrin
authors.initials: AK
authors.lastname: Stock
authors.affiliation: School of Health Sciences, Purdue University, West Lafayette, IN, USA.
authors.forename: Sandy
authors.initials: S
authors.lastname: Snyder
authors.affiliation: Department of Neurology, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: S Elizabeth
authors.initials: SE
authors.lastname: Zauber
authors.affiliation: School of Health Sciences, Purdue University, West Lafayette, IN, USA; Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, IN, USA. Electronic address: udydak@purdue.edu.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Dydak
authors.affiliation: Cognitive Neurophysiology, Department of Child and Adolescent Psychiatry, Faculty of Medicine of the TU Dresden, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Beste
mesh_terms: D000368:Aged; D001288:Attention / Q000502:physiology*; D003220:Conflict, Psychological; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D017072:Neostriatum / Q000378:metabolism*; D010300:Parkinson Disease / Q000503:physiopathology*; D011187:Posture; D011434:Proprioception / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D013788:Thalamus / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D005680:gamma-Aminobutyric Acid
keywords: GABA; Parkinson's disease; Proprioception; Response selection; Sensorimotor integration; Striatum; Thalamus