gms | German Medical Science

62nd Annual Meeting of the German Society of Neurosurgery (DGNC)
Joint Meeting with the Polish Society of Neurosurgeons (PNCH)

German Society of Neurosurgery (DGNC)

7 - 11 May 2011, Hamburg

Impact of the deep brain stimulation of the subthalamic nucleus on decision-making in human – overcoming default bias

Meeting Abstract

  • I. Galazki - Klinik für Neurologie, Otto-v.-Guericke Universität Magdeburg, Deutschland
  • S.M. Fleming - Wellcome Trust Centre for Neuroimaging, University College London, United Kingdom
  • T. Zaehle - Klinik für Neurologie, Otto-v.-Guericke Universität Magdeburg, Deutschland; Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE) Magdeburg, Deutschland
  • R.J. Dolan - Wellcome Trust Centre for Neuroimaging, University College London, United Kingdom
  • H.J. Heinze - Klinik für Neurologie, Otto-v.-Guericke Universität Magdeburg, Deutschland
  • J. Voges - Klinik für Stereotaktische Neurochirurgie, Otto-v.-Guericke Universität Magdeburg, Deutschland

Deutsche Gesellschaft für Neurochirurgie. Polnische Gesellschaft für Neurochirurgen. 62. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit der Polnischen Gesellschaft für Neurochirurgen (PNCH). Hamburg, 07.-11.05.2011. Düsseldorf: German Medical Science GMS Publishing House; 2011. DocP 101

DOI: 10.3205/11dgnc322, URN: urn:nbn:de:0183-11dgnc3226

Published: April 28, 2011

© 2011 Galazki et al.
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Outline

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Objective: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) has become an effective treatment for severe Parkinson's disease (PD). However, evidence is accumulating that DBS of the STN can result in unintended cognitive effects that lie beyond motor control. To deepen our understanding of the role of the STN in human decision-making, in the present study we investigated the impact of DBS of the STN in 8 patients suffering from Parkinson’s disease. Based on recent neurobiological data we hypothesized: if the dominant function of the STN is to inhibit action (Frank 2006, Frank et al., 2009), disruption of its function by DBS in a highly conflicting decision-making paradigm should result in a tendency of the patients to respond. Alternatively, if a prominent role of the STN is to initiate controlled responding (Isoda & Hikosaka 2008, Fleming et al., 2010), disruption of STN functioning should result in a decreased tendency to respond.

Methods: We administered a computerized status quo bias paradigm (Fleming et al., 2010) to 8 patients with Parkinson's disease. Patients were tested in two consecutive sessions: on and off DBS of the bilateral STN. Within each trial, patients’ responses consisted of a go/no-go decision to reject or accept a default, respectively. For analysis, a status quo bias was calculated as the percentage of default acceptance greater than 50% separately for high- and low-difficulty trials.

Results: As expected, patients performed the task faster and made fewer errors for a low difficulty as compared to a high difficulty condition. Furthermore, they performed better under DBS compared to without DBS of the STN. Without DBS there was a greater tendency to accept the default under a high difficulty compared to a low difficulty condition. Thus, similar to healthy subjects, patients exhibited a bias toward accepting the default, resulting in suboptimal decision-making behavior. Importantly, under DBS of the STN, the status quo bias was diminished in that the patients' tendency to accept the default was entirely eliminated. [* paired t-test: P =.05).

Conclusions: Under DBS patients showed an increased tendency to respond and, consequently, decreased default acceptance behavior. This data are in line with recent demonstrations that STN disruption causes impulsive responding in human decision-making (Frank et al., 2009). Consequently, we conclude that a dominant function of the STN is to enable subjects to adaptively "hold your horses", buying more time to settle on the best decision.