Non-extensive entropy and the extraction of BOLD spatial information in event-related functional MRI

Author(s)

Sturzbecher, M. J. ^[1] ; Tedeschi, W. ^[2] ; Cabella, B. C. T. ^[3] ; Baffa, O. ^[4] ; Neves, U. P. C. ^[5] ; de Araujo, D. B. ^[6]

Affiliation

^[1] Univ Sao Paulo. FFCLRP

^[2] Univ Sao Paulo. FFCLRP

^[3] Univ Sao Paulo. FFCLRP

^[4] Univ Sao Paulo. FFCLRP

^[5] Univ Sao Paulo. FFCLRP

^[6] Univ Sao Paulo. FFCLRP

• Document type: Journal article
• Source: Physics in Medicine and Biology; v. 54, n. 1, p. 161-174, JAN 7 2009.
• Web of Science Citations: 10

Abstract

Functional magnetic resonance imaging (fMRI) data analysis has been carried out recently in the framework of information theory, by means of the Shannon entropy. As a natural extension, a method based on the generalized Tsallis entropy was developed to the analysis event-related (ER-fMRI), where a brief stimulus is presented, followed by a long period of rest. The new technique aims for spatial localization neuronal activity due to a specific task. This method does not require a priori hypothesis of the hemodynamic response function (HRF) shape and the linear relation between BOLD responses with the presented task. Numerical simulations were performed so as to determine the optimal values of the Tsallis q parameter and the number of levels, L. In order to avoid undesirable divergences of the Tsallis entropy, only positive q values were studied. Results from simulated data (with L = 3) indicated that, for q = 0.8, the active brain areas are detected with the highest performance. Moreover, the method was tested for an in vivo experiment and demonstrated the ability to discriminate active brain regions that selectively responded to a bilateral motor task. (AU)

• FAPESP's process: 05/03225-7 - Hemodynamic response function of functional magnetic resonance imaging and its application to epilepsy and carotid stenosis
• Grantee: Draulio Barros de Araujo
• Support Opportunities: Research Grants - Young Investigators Grants