Recordings from the depth of the brain in Parkinson’s patients undergoing surgery reveal that a deep brain nucleus communicates with other brain areas at different frequencies.
Deep brain stimulation (DBS) is a form of surgery that is used to treat some of the symptoms of advanced Parkinson's disease. It involves the implantation of wires, with 4 electrodes at their tip to deep brain structures, most commonly an area called ‘the subthalamic nucleus’ (STN) in the two sides of the brain. Following the surgery for a short period of time the other end of the wire implanted in the brain is accessible for recording. For brain researchers this offers a unique opportunity to record invasively the activity of the areas in the human brain not easily accessible to non-invasive methods.
Our team was the first in the world to combine invasive recordings from wires implanted in the brain with non-invasive recordings using a state-of-the-art method called magnetoencephalography (MEG). This method is based on picking up very weak changes in magnetic field around the head caused by synchronized activity of neurons in the brain. By using a MEG scanner we could record the activity of many brain areas at the same time, critically without even touching the patient’s head. This was especially important as the patients in this study had fresh surgical wounds. The MEG scanner also made it possible to determine in which brain area a particular signal originates.
In our paper we present the results of analysis of data recorded at rest when the patients were just sitting quietly with their eyes open for 3 minutes. Using signal analysis techniques we were able to show that there are two distinct frequency bands in which the subthalamic nucleus communicates with the rest of the brain. Critically, each of these bands is allocated to communication with a specific subset of brain regions. This is similar to radio where different frequencies are used for instance by the police and by the airplanes.
In the future we hope to link the pattern of communication between STN and the rest of the brain seen in each patient to the patient’s symptoms and the optimal treatment strategy.
Vladimir Litvak,1,2,* Ashwani Jha,1,3,* Alexandre Eusebio,1 Robert Oostenveld,4 Tom Foltynie,1,5 Patricia Limousin,1,5 Ludvic Zrinzo,1,5 Marwan I. Hariz,1,5 Karl Friston2 and Peter Brown3
1 Sobell Department of Motor Neuroscience, UCL Institute of Neurology, London WC1N 3BG, UK
2 Wellcome Trust Centre for Neuroimaging, UCL Institute of Neurology, London WC1N 3BG, UK
3 Department of Clinical Neurology, University of Oxford, Oxford OX3 9DU, UK
4 Donders Institute of Brain, Cognition and Behaviour, Radbound University, Nijmegen, 6525 EN, Netherlands
5 Unit of Functional Neurosurgery, UCL Institute of Neurology, London WC1N 3BG, UK
*These authors contributed equally to this work.
Reference:
Resting oscillatory cortico-subthalamic connectivity in patients with Parkinson’s disease, Brain, 8 December 2010 doi:10.1093/brain/awq332