title: Local vs. volume conductance activity of field potentials in the human subthalamic nucleus.
abstract: Subthalamic nucleus field potentials have attracted growing research and clinical interest over the last few decades. However, it is unclear whether subthalamic field potentials represent locally generated neuronal subthreshold activity or volume conductance of the organized neuronal activity generated in the cortex. This study aimed at understanding of the physiological origin of subthalamic field potentials and determining the most accurate method for recording them. We compared different methods of recordings in the human subthalamic nucleus: spikes (300-9,000 Hz) and field potentials (3-100 Hz) recorded by monopolar micro- and macroelectrodes, as well as by differential-bipolar macroelectrodes. The recordings were done outside and inside the subthalamic nucleus during electrophysiological navigation for deep brain stimulation procedures (150 electrode trajectories) in 41 Parkinson's disease patients. We modeled the signal and estimated the contribution of nearby/independent vs. remote/common activity in each recording configuration and area. Monopolar micro- and macroelectrode recordings detect field potentials that are considerably affected by common (probably cortical) activity. However, bipolar macroelectrode recordings inside the subthalamic nucleus can detect locally generated potentials. These results are confirmed by high correspondence between the model predictions and actual correlation of neuronal activity recorded by electrode pairs. Differential bipolar macroelectrode subthalamic field potentials can overcome volume conductance effects and reflect locally generated neuronal activity. Bipolar macroelectrode local field potential recordings might be used as a biological marker of normal and pathological brain functions for future electrophysiological studies and navigation systems as well as for closed-loop deep brain stimulation paradigms.NEW & NOTEWORTHYOur results integrate a new method for human subthalamic recordings with a development of an advanced mathematical model. We found that while monopolar microelectrode and macroelectrode recordings detect field potentials that are considerably affected by common (probably cortical) activity, bipolar macroelectrode recordings inside the subthalamic nucleus (STN) detect locally generated potentials that are significantly different than those recorded outside the STN. Differential bipolar subthalamic field potentials can be used in navigation and closed-loop deep brain stimulation paradigms.
authors.affiliation: Department of Medical Neurobiology (Physiology), Institute of Medical Research, Israel-Canada, the Hebrew University-Hadassah Medical School, Jerusalem, Israel.
authors.forename: Odeya
authors.initials: O
authors.lastname: Marmor
authors.affiliation: Department of Medical Neurobiology (Physiology), Institute of Medical Research, Israel-Canada, the Hebrew University-Hadassah Medical School, Jerusalem, Israel.|The Edmond and Lily Safra Center for Brain Research, the Hebrew University, Jerusalem, Israel.
authors.forename: Dan
authors.initials: D
authors.lastname: Valsky
authors.affiliation: Department of Medical Neurobiology (Physiology), Institute of Medical Research, Israel-Canada, the Hebrew University-Hadassah Medical School, Jerusalem, Israel.|The Edmond and Lily Safra Center for Brain Research, the Hebrew University, Jerusalem, Israel.
authors.forename: Mati
authors.initials: M
authors.lastname: Joshua
authors.affiliation: Department of Medical Neurobiology (Physiology), Institute of Medical Research, Israel-Canada, the Hebrew University-Hadassah Medical School, Jerusalem, Israel.|The Brain Division, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.
authors.forename: Atira S
authors.initials: AS
authors.lastname: Bick
authors.affiliation: The Brain Division, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.
authors.forename: David
authors.initials: D
authors.lastname: Arkadir
authors.affiliation: The Brain Division, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.|The Center for Functional and Restorative Neurosurgery, Hadassah-Hebrew University Medical Center, Jerusalem, Israel; and.
authors.forename: Idit
authors.initials: I
authors.lastname: Tamir
authors.affiliation: Department of Medical Neurobiology (Physiology), Institute of Medical Research, Israel-Canada, the Hebrew University-Hadassah Medical School, Jerusalem, Israel.|The Edmond and Lily Safra Center for Brain Research, the Hebrew University, Jerusalem, Israel.
authors.forename: Hagai
authors.initials: H
authors.lastname: Bergman
authors.affiliation: The Brain Division, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.|The Center for Functional and Restorative Neurosurgery, Hadassah-Hebrew University Medical Center, Jerusalem, Israel; and.
authors.forename: Zvi
authors.initials: Z
authors.lastname: Israel
authors.affiliation: Department of Medical Neurobiology (Physiology), Institute of Medical Research, Israel-Canada, the Hebrew University-Hadassah Medical School, Jerusalem, Israel; reitan@partners.org.|The Brain Division, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.|Functional Neuroimaging Laboratory, Brigham and Women's Hospital, Department of Psychiatry, Harvard Medical School, Boston, Massachusetts.
authors.forename: Renana
authors.initials: R
authors.lastname: Eitan
mesh_terms: D000200:Action Potentials; D046690:Deep Brain Stimulation; D004566:Electrodes; D005260:Female; D006801:Humans; D008297:Male; D008959:Models, Neurological; D009434:Neural Pathways / Q000502:physiology / Q000503:physiopathology; D010300:Parkinson Disease / Q000503:physiopathology / Q000628:therapy; D010507:Periodicity; D020531:Subthalamic Nucleus / Q000502:physiology* / Q000503:physiopathology
keywords: bipolar recordings; deep brain stimulation; macroelectrode recordings; microelectrode recordings; neurophysiological navigation