Changes in activity in brain regions one week and one year after surgery.

<p>The table shows the mean amplitudes (and their variances) and source powers in different range of frequencies in DBS ON and OFF conditions (A) one week after surgery and (B) one year after surgery.</p

Application of the null-beamformer.

<p>The figure shows the estimated power of the sources in the mid-sagittal (top) and mid-coronal (bottom) view following the use of A) conventional beamformer and B) null-beamformer. The threshold value is 70% of the peak of the power spectrum. As can be seen, the null-beamformer has successfully removed the interference outside of the brain. Please note that in order to best depict the sources of brain activity, the null location is approximate and its actual location is in other anatomical planes (not shown).</p

Comparison of the accuracy of using null and conventional beamformers for the localization of known locations of DBS electrodes.

<p>A) We used the null beamformer to localize the DBS electrodes when the stimulator was ON at 130 Hz. The coronal view of the lowest electrodes as localised on the patient’s MRI (red markers) compared with the overlay of contours of the estimated power using the null-beamformer. Two sagittal slices through lower left electrode and sagittal view of the lower right electrode. The fit is especially good on the left side. B) Similar localization using the conventional beamformer method shows a less good fit. In particular the method is unable to localize both electrodes.</p