Oliver Gronz

Advanced Methods for Target Navigation using Microelectrode Recordings in Stereotactic Neurosurgery for Deep Brain Stimulation

This study describes novel methods for navigating and placing of electrodes into specific structures in the basal ganglia for deep brain stimulation (DBS), as it is common in the treatment of Parkinsons disease. Critical to these procedures in neurosurgery is the localization and identification of different target structures such as subthalamic nucleus (STN) along the electrodes trajectory and finding the best position for the stimulating electrode. Typically, microelectrode recordings (MER) of local neural activity along up to five parallel trajectories are used by neurosurgeons for detecting the target region and creating the anatomic positions of the electrodes by imagination. We developed a method for automatic classification of the MER signals, which provides an electrode model with patient specific borders of the STN. In addition, a method is provided for finding the best matching of the electrode model with a 3D model of the STN. As a result, a 2.5D visualization of the target region is produced with the most probable positions of the electrodes and their intersections.

Fuzzy logic-based rainfall-runoff modelling using soil moisture measurements to represent system state

Abstract Initial catchment state, such as soil moisture, strongly controls rainfall—runoff transformation processes. However, due to the high spatial and temporal variability of soil moisture, point measurements may not always be suitable to represent the actual system state of a whole catchment as required in distributed catchment modelling. In this study a fuzzy rule-based system (FRBS) using the Takagi-Sugeno-Kang approach has been developed using soil moisture and rainfall as input variables to predict the actual discharge at the catchment outlet. Four soil moisture probes from the hydrological test site Dürreych (Black Forest, southwest Germany) were selected, each of them representing a particular runoff generation process (saturation excess flow, infiltration excess flow, slow and fast interflow, return flow). After manual calibration, the simulated peak discharges were very similar to the measured values. Furthermore, the pattern of rule activation in the FRBS reflected the complex, highly nonlinear behaviour of the catchment. Thus, in the FRBS framework, the measurements of soil moisture at representative locations could be used as representation for the actual system state, allowing for an entirely data-driven prediction of the runoff response using rainfall.