The Parkinson's Appeal for Deep Brain Stimulation


Principal Investigators:
Professor Marwan Hariz (MH)
Professor Marjan Jahanshahi (MJ)
Dr Patricia Limousin (PL)

The Functional Neurosurgery Unit (FNU), Institute of Neurology, Queen Square, London, UK was established in October 2002. It provides a clinical service for Deep Brain Stimulation (DBS) for Parkinson's Disease and other movement disorders. In addition, it has a major role in developing research into DBS: the overall objective is a better understanding of DBS so that it can be applied more effectively and to a wider range of neurological disorders, including pain and headache.

Research in the FNU is currently directed at improving the accuracy and efficacy of DBS, including the development of better imaging and other techniques to allow more precise location of the DBS electrodes. A major thrust of the research concerns the effect of DBS on cognitive function and mood: this has very important clinical consequences because we must ensure that improvement in motor function is not compromised by any unwanted cognitive or emotional side-effects. The Unit is also taking advantage of the unique possibility of investigating the physiology of the motor system in patients with Movement Disorders. This is made possible because in the short period (2-3 days) between electrode implant and connections to the pacemaker, it is necessary to record and stimulate through the electrodes to optimise the stimulation parameters for each patient. Thus we can learn about the activity underlying movement disorders with direct recordings from the responsible brain structures. Finally, the Unit is playing a key role in the MRC-funded PDSURG clinical trial, which is making a systematic comparison of the different treatments for Parkinson's disease.

The techniques used in this research include MR-based brain imaging and electrophysiology (recording of brain local field potentials, evoked potentials and EEG), combined with sophisticated signal analysis of these recordings. Motor function, including gait analysis and skilled hand function, will be monitored using as variety of video-based motion analysis techniques. Research on cognition and mood relies on the use of neuropsychological test apparatus and batteries of standard and custom-made tests. Quality of life questionnaires are used with patients, their carers and families.

I. Research Work in Progress
The following research projects are in progress in the FNU. The leading PI is identified in parentheses


  • Accuracy of non-microelectrode-guided functional neurosurgery using MRI directed targeting and the Leksell frame (MH)
  • Value and pitfalls of DBS as a surgical technique: 10 years of experience (MH)

Cognitive function and mood:

  • Effect of surgery for DBS on cognitive executive function (MJ)
  • Word fluency with DBS on versus off (MJ)
  • DBS and visual conditional associative learning (MJ)
  • Impact of surgery for DBS on motivation, mood and quality of life (MJ)
  • Field potentials from the basal ganglia during processing of emotional stimuli (MH)

Physiology/Motor function:

  • Effect of DBS on the EEG (PL)
  • Use of evoked potentials for functional localization of the electrode contacts (PL)
  • Response initiation and suppression in a go no go RT task with and without DBS (MJ)


  • The mechanisms and time course of clinical improvement in dystonia following DBS (PL)
  • PDSURG trial- Clinical outcome study of DBS (PL, MH, MJ)
  • The Assessment of changes in brain activation patterns in response to Deep Brain Stimulation in patients with Parkinson's Disease, using Functional Magnetic Resonance Imaging

II. Sources of Research Funding

1. Current research funding:

  • Five year grant from the National Institute of Neurological Disorders, National Institute of Health , USA (full funding for MJ)
  • Supplementary Grant from the National Institute of Neurological Disorders, National Institute of Health , USA (MJ)
  • PhD Studentship from the Parkinson's Disease Society (MJ)
  • Collaborator on grant from the National Institute of Neurological Disorders, National Institute of Health, USA to Dr Corcos (PL)
  • MRC Programme grants to Professor Rothwell and Dr Brown (part-funding PL)
  • PhD studentship from the Brain Research Trust (PL)
  • Wellcome Travelling Fellowship (Dr Serge Pinto, PL, MJ)
  • Grant From Fondation pour la Recherche Medical (Dr Stephane Thobois, PL, MJ)

2. Future grant applications:

  • PhD Studentship or grant funding for Mr Zrinzo (MH)
  • Proposal on recording of activity from implanted electrodes during performance of cognitive and motor tasks which is to be submitted to the Wellcome Trust. (MJ)
  • Medical Research Council or Brain Research Trust PhD studentship for work on cognitive and affective aspects of DBS (MJ)

Please also refer to Bibliography for details of papers, lectures and presentations by FNU staff >>



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