Glossary🔗
The Glossary provides short definitions of vocabulary specific to the neuromodulation and general neuroimaging concepts.
- anatomical landmark🔗
- anatomical landmarks🔗
- fiducial🔗
- fiducial point🔗
- fiducial points🔗
Fiducials are objects placed in the field of view of an imaging system to act as known spatial references that are easy to localize. In neuroimaging, fiducials are often placed on anatomical landmarks such as the nasion (NAS) or left/right preauricular points (LPA and RPA).
These known reference locations are used to define a coordinate system for localizing sensors (hence NAS, LPA and RPA are often called “cardinal points” because they define the cardinal directions of the head coordinate system). The cardinal points are also useful when co-registering measurements in different coordinate systems.
Due to the common neuroimaging practice of placing fiducial objects on anatomical landmarks, the terms “fiducial”, “anatomical landmark”, and “cardinal point” are often (erroneously) used interchangeably.
- antenna🔗
- coil🔗
- magnetic coil🔗
- TMS antenna🔗
- TMS coil🔗
The coil, or antenna, is the part of the TMS system that emits the magnetic field. The coil is an electrical conductor in the shape of a coil, in which an electrical current is passed through to generate a magnetic field.
- motor threshold🔗
The motor threshold is defined as the minimum single pulse TMS energy needed to observe an Abductor Pollicis Brevis contraction (APB or muscle in the hand that functions as an abductor of the thumb).
The motor threshold is measured as a percentage of the maximum stimulator output and is determined by discharging a magnetic coil over the motor cortex. The motor cortex area on the brain is used as an indicator because it’s one of few areas in the brain where TMS is associated with easily observable phenomena.