Indian Journal of Radiology and Imaging Indian Journal of Radiology and Imaging

NEURORADIOLOGY
Year
: 2010  |  Volume : 20  |  Issue : 3  |  Page : 182--187

Functional mapping of language networks in the normal brain using a word-association task


Shantanu Ghosh1, Amrita Basu2, Senthil S Kumaran3, Subash Khushu4 
1 Behavioral and Cognitive Science Lab, Department of Humanities and Social Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110 016, India
2 Center for Linguistics, Jawaharlal Nehru University, New Delhi 110 067, *Now at Center for Cognitive Science, Jadavpur University, Kolkata 700 032, India
3 Department of NMR, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110 029, India
4 NMR Research Center, Institute of Nuclear Medicine and Allied Sciences, Timarpur, Delhi 110 054, India

Correspondence Address:
Shantanu Ghosh
Behavioral and Cognitive Science Lab, Department of Humanities and Social Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110 016
India

Background: Language functions are known to be affected in diverse neurological conditions, including ischemic stroke, traumatic brain injury, and brain tumors. Because language networks are extensive, interpretation of functional data depends on the task completed during evaluation. Aim: The aim was to map the hemodynamic consequences of word association using functional magnetic resonance imaging (fMRI) in normal human subjects. Materials and Methods: Ten healthy subjects underwent fMRI scanning with a postlexical access semantic association task vs lexical processing task. The fMRI protocol involved a T2*-weighted gradient-echo echo-planar imaging (GE-EPI) sequence (TR 4523 ms, TE 64 ms, flip angle 90º) with alternate baseline and activation blocks. A total of 78 scans were taken (interscan interval = 3 s) with a total imaging time of 587 s. Functional data were processed in Statistical Parametric Mapping software (SPM2) with 8-mm Gaussian kernel by convolving the blood oxygenation level-dependent (BOLD) signal with an hemodynamic response function estimated by general linear method to generate SPM{t} and SPM{F} maps. Results: Single subject analysis of the functional data (FWE-corrected, P≤0.001) revealed extensive activation in the frontal lobes, with overlaps among middle frontal gyrus (MFG), superior, and inferior frontal gyri. BOLD activity was also found in the medial frontal gyrus, middle occipital gyrus (MOG), anterior fusiform gyrus, superior and inferior parietal lobules, and to a smaller extent, the thalamus and right anterior cerebellum. Group analysis (FWE-corrected, P≤0.001) revealed neural recruitment of bilateral lingual gyri, left MFG, bilateral MOG, left superior occipital gyrus, left fusiform gyrus, bilateral thalami, and right cerebellar areas. Conclusions: Group data analysis revealed a cerebellar-occipital-fusiform-thalamic network centered around bilateral lingual gyri for word association, thereby indicating how these areas facilitate language comprehension by activating a semantic association network of words processed postlexical access. This finding is important when assessing the extent of cognitive damage and/or recovery and can be used for presurgical planning after optimization.


How to cite this article:
Ghosh S, Basu A, Kumaran SS, Khushu S. Functional mapping of language networks in the normal brain using a word-association task.Indian J Radiol Imaging 2010;20:182-187


How to cite this URL:
Ghosh S, Basu A, Kumaran SS, Khushu S. Functional mapping of language networks in the normal brain using a word-association task. Indian J Radiol Imaging [serial online] 2010 [cited 2020 Jun 6 ];20:182-187
Available from: http://www.ijri.org/article.asp?issn=0971-3026;year=2010;volume=20;issue=3;spage=182;epage=187;aulast=Ghosh;type=0