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Journal of Biomedical Optics • Open Access

Load-dependent brain activation assessed by time-domain functional near-infrared spectroscopy during a working memory task with graded levels of difficulty
Author(s): Erika Molteni; Giuseppe Baselli; Sergio Cerutti; Anna Maria Bianchi; Davide Contini; Matteo Caffini; Rinaldo Cubeddu; Alessandro Torricelli; Lorenzo Spinelli

Paper Abstract

We evaluated frontal brain activation during a mixed attentional/working memory task with graded levels of difficulty in a group of 19 healthy subjects, by means of time-domain functional near-infrared spectroscopy (fNIRS). Brain activation was assessed, and load-related oxy- and deoxy-hemoglobin changes were studied. Generalized linear model (GLM) was applied to the data to explore the metabolic processes occurring during the mental effort and, possibly, their involvement in short-term memorization. GLM was applied to the data twice: for modeling the task as a whole and for specifically investigating brain activation at each cognitive load. This twofold employment of GLM allowed (1) the extraction and isolation of different information from the same signals, obtained through the modeling of different cognitive categories (sustained attention and working memory), and (2) the evaluation of model fitness, by inspection and comparison of residuals (i.e., unmodeled part of the signal) obtained in the two different cases. Results attest to the presence of a persistent attentional-related metabolic activity, superimposed to a task-related mnemonic contribution. Some hemispherical differences have also been highlighted frontally: deoxy-hemoglobin changes manifested a strong right lateralization, whereas modifications in oxy- and total hemoglobin showed a medial localization. The present work successfully explored the capability of fNIRS to detect the two neurophysiological categories under investigation and distinguish their activation patterns.

Paper Details

Date Published: 4 May 2012
PDF: 12 pages
J. Biomed. Opt. 17(5) 056005 doi: 10.1117/1.JBO.17.5.056005
Published in: Journal of Biomedical Optics Volume 17, Issue 5
Show Author Affiliations
Erika Molteni, Politecnico di Milano (Italy)
Giuseppe Baselli, Politecnico di Milano (Italy)
Sergio Cerutti, Politecnico di Milano (Italy)
Anna Maria Bianchi, Politecnico di Milano (Italy)
Davide Contini, Politecnico di Milano (Italy)
Matteo Caffini, Politecnico di Milano (Italy)
Rinaldo Cubeddu, Politecnico di Milano (Italy)
Alessandro Torricelli, Politecnico di Milano (Italy)
Lorenzo Spinelli, Istituto di Fotonica e Nanotecnologie (Italy)

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