Functional near‐infrared spectroscopy for the assessment of overt reading

Abstract

Functional near-infrared spectroscopy (fNIRS) has become increasingly established as a promising technique for monitoring functional brain activity. To our knowledge, no study has yet used fNIRS to investigate overt reading of irregular words and nonwords with a full coverage of the cerebral regions involved in reading processes. The aim of our study was to design and validate a protocol using fNIRS for the assessment of overt reading. Twelve healthy French-speaking adults underwent one session of fNIRS recording while performing an overt reading of 13 blocks of irregular words and nonwords. Reading blocks were separated by baseline periods during which participants were instructed to fixate a cross. Sources (n = 55) and detectors (n = 16) were placed bilaterally over frontal, temporal, parietal, and occipital regions. Two wavelengths were used: 690 nm, more sensitive to deoxyhemoglobin (HbR) concentration changes, and 830 nm, more sensitive to oxyhemoglobin (HbO) concentration changes. For all participants, total hemoglobin (HbT) concentrations (HbO + HbR) were significantly higher than baseline for both irregular word and nonword reading in the inferior frontal gyri, the middle and superior temporal gyri, and the occipital cortices bilaterally. In the temporal gyri, although the difference was not significant, [HbT] values were higher in the left hemisphere. In the bilateral inferior frontal gyri, higher [HbT] values were found in nonword than in irregular word reading. This activation could be related to the grapheme-to-phoneme conversion characterizing the phonological pathway of reading. Our findings confirm that fNIRS is an appropriate technique to assess the neural correlates of overt reading.

Processing Printed Words in Literary Arabic and Spoken Arabic: An fNIRS Study

“…The neurocognitive outcomes of the present study indicate, as in previous studies (Safi et al, 2012), that fNIRS technology might be useful tool to investigate reading processes and understanding the differences that might be reflected in the brain activity. As expected, high activation was observed in the left hemisphere, in regions classically involved in reading processes.…”

Recruitment of the left precentral gyrus in reading epilepsy: A multimodal neuroimaging study

“…The patient read French irregular words (e.g., coefficient) (lexical reading pathway) and nonwords (e.g., nomus) (phonological reading pathway) presented on a computer screen in a block-design paradigm during MEG, fNIRS, and fMRI–EEG recordings. Nonwords were matched to irregular words for length (number of letters) and phonological complexity (syllabic structure, number of phonemes and syllables) (see [11] for details on stimuli's characteristics). Reading blocks (20 s) were separated by a baseline condition (between 5 and 35 s.) during which the patient had to fix a cross presented in the center of the screen.…”

Concurrent anodal transcranial direct-current stimulation and motor task to influence sensorimotor cortex activation

“…The fNIRS values retained for statistical analysis were changes in the averaged O 2 Hb and HHb computed over the 10 task blocks using the integral between 5 to 25 seconds out of the 30 seconds of the task. This integral analytic approach allows quantifying the concentration changes over time while being sensitive to task-related changes on O 2 Hb and HHb regardless of the shape of the hemodynamic response profile (Näsi et al, 2010;Safi et al, 2012). An index of hemoglobin differential (Hb diff = O 2 Hb -HHb) was also used to evaluate the level of cortical activation (Lu et al, 2015).…”