Impact of non-brain anatomy and coil orientation on inter- and intra-subject variability in TMS at midline
Date
Authors
Major Professor
Advisor
Committee Member
Journal Title
Journal ISSN
Volume Title
Publisher
Authors
Research Projects
Organizational Units
Ames National Laboratory is a government-owned, contractor-operated national laboratory of the U.S. Department of Energy (DOE), operated by and located on the campus of Iowa State University in Ames, Iowa.
For more than 70 years, the Ames National Laboratory has successfully partnered with Iowa State University, and is unique among the 17 DOE laboratories in that it is physically located on the campus of a major research university. Many of the scientists and administrators at the Laboratory also hold faculty positions at the University and the Laboratory has access to both undergraduate and graduate student talent.
The Department of Electrical and Computer Engineering (ECpE) contains two focuses. The focus on Electrical Engineering teaches students in the fields of control systems, electromagnetics and non-destructive evaluation, microelectronics, electric power & energy systems, and the like. The Computer Engineering focus teaches in the fields of software systems, embedded systems, networking, information security, computer architecture, etc.
History
The Department of Electrical Engineering was formed in 1909 from the division of the Department of Physics and Electrical Engineering. In 1985 its name changed to Department of Electrical Engineering and Computer Engineering. In 1995 it became the Department of Electrical and Computer Engineering.
Dates of Existence
1909-present
Historical Names
- Department of Electrical Engineering (1909-1985)
- Department of Electrical Engineering and Computer Engineering (1985-1995)
Related Units
- College of Engineering (parent college)
- Department of Physics and Electrical Engineering (predecessor)
Journal Issue
Is Version Of
Versions
Series
Department
Abstract
Objective: To investigate inter-subject variability with respect to cerebrospinal fluid thickness and brain-scalp distance, and to investigate intra-subject variability with different coil orientations.
Methods: Simulations of the induced electric field (E-Field) using a figure-8 coil over the vertex were conducted on 50 unique head models, and varying orientations on 25 models. Metrics exploring stimulation intensity, spread, and localization were used to describe inter-subject variability and effects of non-brain anatomy.
Results: Both brain-scalp distance and CSF thickness were correlated with weaker stimulation intensity, and greater spread. Coil rotations show that for the dorsal portion of the stimulated brain, E-Field intensities are highest when the anterior-posterior axis of the coil is perpendicular to the longitudinal fissure, but highest for the medial portion of the stimulated brain when the coil is oriented parallel to the longitudinal fissure.
Conclusions: Normal anatomical variation in healthy individuals leads to significant differences in the site of TMS, the intensity and the spread. These variables are generally neglected but could explain significant variability in basic and clinical studies.
Significance: This is the first work to show how brain-scalp distance and cerebrospinal fluid thickness influence focality, and to show the disassociation between dorsal and medial TMS.
Comments
This is a manuscript of an article published as Lee, Erik G., P. Rastogi, R. L. Hadimani, D. C. Jiles, and Joan A. Camprodon. "Impact of non-brain anatomy and coil orientation on inter-and intra-subject variability in TMS at midline." Clinical Neurophysiology (2018). DOI: 10.1016/j.clinph.2018.04.749. Posted with permission.