Paper Information

Title: 

PARAMETER ESTIMATION OF BALLOON MODEL IN FMRI USING STEEPEST DESCENT METHOD

Type: PAPER
Author(s): KARIMI MOHAMMAD MEHDI,HOSSEINZADEH GHOLAM ALI,SETAREHDAN SEYYED KAMALODDIN
 
 
 
Name of Seminar: IRANIAN CONFERENCE ON BIOMEDICAL ENGINEERING
Type of Seminar:  CONFERENCE
Sponsor:  ANJOMANE MOHANDESI PEZESHKI IRAN
Date:  2004Volume 11
 
 
Abstract: 

HEMODYNAMIC SYSTEM, AS AN INTERMEDIATE PROCESS BETWEEN NEURAL ACTIVITY AND MEASURED FMRI SIGNAL, IS RECENTLY MODELED WITH NONLINEAR APPROACHES. AMONG FEW MODELS INTRODUCED SO FAR, THE BALLOON IS THE MOST COMPLETE MODEL, WHICH ALSO HAS SOME PHYSIOLOGICAL INTERPRETATIONS. IN SPITE OF ITS CAPABILITIES, THE BALLOON MODEL NEEDS A NONLINEAR SYSTEM IDENTIFICATION PROCEDURE FOR ESTIMATING ITS PARAMETERS. AFTER THIS STEP, THE ANALYST WILL BE ABLE TO INTERPRET THE PARAMETERS, OR USE THE IDENTIFIED MODEL FOR ACTIVATION DETECTION.
IN THIS PAPER, WE INTRODUCED A METHODOLOGY FOR ESTIMATING THE PARAMETERS OF THIS MODEL BASED ON STEEPEST DESCENT ALGORITHM. WE FIRST USED A SIMPLE STRATEGY (BASED ON CORRELATION) TO IDENTIFY THE ACTIVE VOXELS. THEN USING THE STEEPEST DESCENT ALGORITHM WE FIND THE BEST SET OF PARAMETERS (IN THE MODEL) THAT FIT TO THE MEASURED FMRI DATA (TIME SERIES OF EACH ACTIVATED VOXEL). ESTIMATED PARAMETERS ARE CONSISTENT WITH PREVIOUS STUDIES THAT USED OTHER COMPLEX SYSTEM IDENTIFICATION APPROACHES. THIS METHOD AND ESTIMATED PARAMETERS CAN BE USED IN FUTURE STUDIES OF FMRI.

 
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