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Research Papers

Investigation of the prefrontal cortex in response to duration-variable anagram tasks using functional near-infrared spectroscopy

[+] Author Affiliations
Fenghua Tian

The University of Pennsylvania, School of Medicine, Department of Biophysics and Biochemistry, Philadelphia, Pennsylvania 19104 and The University of Texas at Arlington, Department of Bioengineering, P.O. Box 19138, Arlington, Texas 76019

Britton Chance

The University of Pennsylvania, School of Medicine, Department of Biophysics and Biochemistry, Philadelphia, Pennsylvania 19104

Hanli Liu

The University of Texas at Arlington, Department of Bioengineering, P.O. Box 19138, Arlington, Texas 76019

J. Biomed. Opt. 14(5), 054016 (March 24, 2009July 03, 2009July 27, 2009October 07, 2009). doi:10.1117/1.3241984
History: Received March 24, 2009; Revised July 03, 2009; Accepted July 27, 2009; Published October 07, 2009
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We hypothesize that nonlinearity between short-term anagram tasks and corresponding hemodynamic responses can be observed by functional near-infrared spectroscopy (fNIRS) in the prefrontal cortex (PFC). The PFC of six human subjects in response to anagram tasks is investigated using multichannel fNIRS. Concentration changes of oxyhemoglobin and deoxyhemoglobin in the PFC are measured with variable anagram durations and at two difficulty levels (four- and six-letter anagrams). The durations to perform the selected anagram tasks range from several seconds to more than one minute. The dorsolateral PFC areas exhibit consistent and strong hemodynamic deactivation during and shortly after task execution. The superposition principle of a linear system is employed to investigate nonlinear hemodynamic features among three task duration subgroups: D1 = 2.0 sec, D2 = 4.0 sec, and D3 = 8.0 sec. Such analysis shows clear nonlinearity in hemodynamic responses on the PFC with task durations shorter than 4 sec. Our observation of significant deactivation in early hemodynamic responses in the PFC is consistent with multiple fNIRS studies and several reports given in the field of functional magnetic resonance imaging. A better understanding of nonlinearity in fNIRS signals will have potential for us to investigate brain adaptation and to extrapolate neuronal activities from hemodynamic signals.

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© 2009 Society of Photo-Optical Instrumentation Engineers

Citation

Fenghua Tian ; Britton Chance and Hanli Liu
"Investigation of the prefrontal cortex in response to duration-variable anagram tasks using functional near-infrared spectroscopy", J. Biomed. Opt. 14(5), 054016 (March 24, 2009July 03, 2009July 27, 2009October 07, 2009). ; http://dx.doi.org/10.1117/1.3241984


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