Functional anatomy of execution, mental simulation, observation, and verb generation of actions: A meta-analysis


  • The location of significant rCBF changes identified on PET images is expressed as 3D coordinates (x, y, z) in reference to the standardized coordinate system of Talairach and Tournoux [1988]. This system uses the AC-PC plane (anterior and posterior commissures) as the z origin and the VCA (vertical perpendicular to AC) as the y origin. SPM95 uses Talairach and Tournoux [1988] coordinates, SPM 96 and SPM 99 use a standard brain from the Montreal Neurological Institute (MNI). The problem introduced by the MNI standard brain is that its linear transformations do not completely match the brain into the Talairach space. The MNI brain is slightly larger than the Talairach brain. In order to make direct comparison across studies, we have chosen to translate the Talairach coordinates acquired before 1996 into MNI coordinates according to the following formula (given by Andreas Meyer-Lindenberg of Unit on PET, Clinical Brain Disorders Branch, National Institute of Mental Health on SPM mail list):


    1.36 X_talairach + 0.91


    1.03 Y_talairach + 3.42


    -0.06 Y_talairch+1.14 Z_talairach + 0.31.

    Even if this method has been used to reduce the variability between studies, it does not exclude methodological factor variability due to the analysis procedures—for example, intersubject averaging and spatial resolution.


There is a large body of psychological and neuroimaging experiments that have interpreted their findings in favor of a functional equivalence between action generation, action simulation, action verbalization, and perception of action. On the basis of these data, the concept of shared motor representations has been proposed. Indeed several authors have argued that our capacity to understand other people's behavior and to attribute intention or beliefs to others is rooted in a neural, most likely distributed, execution/observation mechanism. Recent neuroimaging studies have explored the neural network engaged during motor execution, simulation, verbalization, and observation. The focus of this meta-analysis is to evaluate in specific detail to what extent the activated foci elicited by these studies overlap. Hum. Brain Mapping 12:1–19, 2001. © 2001 Wiley-Liss, Inc.