Answer: The Talairach coordinate system is a way to target specific regions of the brain in three dimensional space.
From https://www.umm.uni-heidelberg.de/inst/cbtm/ckm/research/fmri/hmeyer/fmri_basics/grid.html
In 1967, neurosurgeons Jean Talairach and Gabor Szikla developed a system for identifying small regions of the brain during epilepsy surgery. They developed the system using a 3D grid of the brain, and could therefore point to parts of the brain precisely. The Talairach system depends on zeroing the coordinates around the anterior commissure, the posterior commissure, and six other points in the brain - the extreme ends in each of the three axes (dorsoventral, anteroposterior, lateromedial). Talairach coordinates are often used in the analysis of a magnetic resonance image scan (MRI) to ensure that blood oxygenation signals in the subject match with some normalized brain.
In the Talairach coordinate system, brain regions are labeled by their Brodmann numbers.
A major caveat of using the Talairach coordinate system is that the coordinates were based off a single, post-mortem case study rather than an average of multiple brains.
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