Intersubject variability in functional neuroanatomy of silent verb generation: Assessment by a new activation detection algorithm based on amplitude and size information
NeuroImage. 1995-12-01; 2(4): 253-263
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1. Neuroimage. 1995 Dec;2(4):253-63.
Intersubject variability in functional neuroanatomy of silent verb generation:
assessment by a new activation detection algorithm based on amplitude and size
Crivello F(1), Tzourio N, Poline JB, Woods RP, Mazziotta JC, Mazoyer B.
(1)Groupe d’Imagerie Neurofonctionnelle, Service Hospitalier Frédéric Joliot,
CEA-DRM, Orsay, France.
We present an experimental evaluation of a new algorithm for the detection of
activated areas in brain functional maps. The new algorithm, named HMSD, is based
on a hierarchical multiscale description of the difference image in terms of
connected objects. Size and magnitude of each object are simultaneously tested
with respect to a bidimensional frequency distribution derived using Monte-Carlo
simulations under the null hypothesis. In the present work. HMSD was applied to
the analysis of a silent verb generation PET activation protocol conducted in six
right-handed subjects. Applied to single-subject data. HMSD reveals activation
located in the left inferior frontal gyrus in three subjects (two in the pars
opercularis, one in the pars triangularis), and in the pars opercularis of the
right inferior frontal gyrus in one case, the latter being combined to a crossed
cerebellar activation. Overall, single-case results were consistent with the
analyses of stereotactically averaged data. Despite a 2D implentation. HMSD
detection performances of averaged data were better than that obtained with the
2D version of statistical parametric mapping (SPM) and comparable to that of the
3D version of SPM.
PMID: 9343610 [Indexed for MEDLINE]