On the effects of spatial filtering - A comparative fMRI study of episodic memory encoding at high and low resolution

被引:31
作者
Fransson, P [1 ]
Merboldt, KD
Petersson, KM
Ingvar, M
Frahm, J
机构
[1] Karolinska Inst, Karolinska Hosp, MR Res Ctr, S-10401 Stockholm, Sweden
[2] Karolinska Inst, Karolinska Hosp, Dept Clin Neurosci, Cognit Neurophysiol Res Grp, S-10401 Stockholm, Sweden
[3] Biomed NMR Forsch GmbH, Max Planck Inst Biophys Chem, D-37070 Gottingen, Germany
关键词
D O I
10.1006/nimg.2002.1079
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
The effects of spatial filtering in functional magnetic resonance imaging were investigated by reevaluating the data of a previous study of episodic memory encoding at 2 X 2 X 4-mm(3) resolution with use of a SPM99 analysis involving a Gaussian kernel of 8-mm full width at half maximum. In addition, a multisubject analysis of activated regions was performed by normalizing the functional images to an approximate Talairach brain atlas. In individual subjects, spatial filtering merged activations in anatomically separated brain regions. Moreover, small foci of activated pixels which originated from veins became blurred and hence indistinguishable from parenchymal responses. The multisubject analysis resulted in activation of the hippocampus proper, a finding which could not be confirmed by the activation maps obtained at high resolution. It is concluded that the validity of multisubject fMRI analyses can be considerably improved by first analyzing individual data sets at optimum resolution to assess the effects of spatial filtering and minimize the risk of signal contamination by macroscopically visible vessels. (C) 2002 Elsevier Science (USA).
引用
收藏
页码:977 / 984
页数:8
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