Location-probability profiles for the mouth region of human primary motor-sensory cortex: Model and validation

The month representation of the human, primary motor cortex (M1) is not rel iably identified by surface anatomy but may be reliably localized by means of spatial coordinates. For this report, three quantitative metanalyses wer e performed which jointly described the mean location, location variability and location-probability profiles of the human M1-mouth representation. Fi rst, a literature metanalysis of intersubject functional-area variability w as performed using eleven, per-subject studies, each of which reported a co ordinate-referenced measure of intersubject variability for one or more bra in areas. From these data, a weighted-mean value for intersubject variabili ty was computed, which proved to be small (5.6 mm, standard deviation), con sistent across coordinate axes (x, y, z), and consistent across brain areas . Second, a literature metanalysis of the location of M1-mouth was performe d using seven, coordinate-referenced, group-mean studies (71 subjects in al l), each of which reported a grand-average location for MI-mouth. From this , a weighted-mean location and weighted values for total variability (inter laboratory plus interindividual) were determined. Using these two literatur e metanalyses as input data, location-probability profiles were computed fo r the cardinal axes (x, y, and z) of the reference space, using the functio nal volumes modeling (FVM) statistical model. Third, an original-data metan alysis was performed on in-house PET data from 30 normal subjects performin g overt-speech tasks. MI-mouths mean location, location variability, and lo cation-probability profiles were consistent with those conjointly modeled b y FVM from the two literature metanalyses. Collectively, these observations provide a detailed, consensus probabilistic description of the location of the human M1-mouth representation in standardized coordinates. (C) 2001 Ac ademic Press.