fNIRS-based investigation of the Stroop task after TBI

Abstract

To evaluate neural changes during a Stroop task among individuals with TBI using functional near-infrared spectroscopy (fNIRS). Thirteen healthy controls and 14 patients with moderate to severe TBI were included in this study. Oxygenated hemoglobin (HbO) was recorded every tenth of a second using a 52-channel fNIRS unit. Data were acquired using a block design during a Stroop task (i.e., Condition A = Dot Color Naming, Condition B = Incongruent Condition). Visual stimuli were presented on a computer monitor. Behaviorally, response accuracy was similar between groups for condition A, but the TBI group made more errors than the control group during condition B. During condition A, the patient group demonstrated significant increases in HbO within bilateral frontal regions compared to controls (p < 0.01). When examining the Stroop interference effect (B-A), controls showed increased HbO in bilateral frontal lobes and left inferior parietal region suggesting increased neural response to increased cognitive demand, whereas no differences were detected among the TBI group (p < 0.05). No between group differences in latency of HbO response was observed during either condition. While the TBI group performed as accurately as controls on the simpler dot color naming condition of the Stroop task, neural activity was greater within the frontal lobes during this relatively simple task among the TBI group suggesting neural inefficiency. Furthermore, the spatial distribution of neural activity related to the interference effect was not different among patients, suggesting the neural demand for the simpler task was comparable to that of the more cognitive demanding task among the TBI sample. The results suggest that fNIRS can identify frontal lobe inefficiency in TBI commonly observed with fMRI.

Neurobiological Basis of Brain Blood Oxygenation Responses Correlated with Cognitive Stroop Task Performance Before and After an Acute Bout of Aerobic Exercise

“…The light frequencies at infrared and near-infrared wavelengths are used to differentiate the relative levels of oxy-Hb and deoxy-Hb in the cortical tissue (Plenger et al, 2016; Tam & Zouridakis 2014; Yamada et al, 2012). In this technique, light is directed into the brain tissue by fibre-optic bundles called optodes (emitters).…”

“…The modified Beer-Lambert law is used to calculate the optical density or absorption changes based on light scattering through the brain tissue, after filtering the raw data for cardiac oscillations (Scholkmann et al, 2014; Schytz, et al, 2009; Butti et al et al, 2007; Delpy et al, 1988). fNIRS gives insight into the metabolic rate of the cortical pyramidal neuronal and glial responses, through the brain blood oxygenation changes in the prefrontal or motor cortices (Plenger et al, 2016; Tam & Zouridakis 2014; Yamada et al, 2012; Merzagora et al, 2009). Brain activation using the fNIRS technique is deduced from an increase in oxy-Hb and a simultaneous decrease in deoxy-Hb during an excitatory cognitive task (Vazquez et al, 2010; Schecklmann et al, 2008).…”

“…fNIRS technology has been widely used for quantifying Stroop task response in the brain (Plenger et al, 2016; Lambrick et al, 2016; Tam & Zouridakis 2014; Byun et al, 2014). Usually non-parametric correlations are used to correlate the non-normally distributed Stroop task performance data with normally distributed brain blood oxygenation data (Yanagisawa et al, 2010).…”

Sensory source for stroop effects in persons after TBI: support from fNIRS-based investigation

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We recently read the interesting and informative paper BfNIRS-based investigation of performance on a Stroop task after TBI^ (Plenger et al 2015). The authors were careful not to interpret the behavioral data as supporting a deficit in selective-attention in TBI, but rather that the BTBI group had significantly more difficulty performing the incongruent task.^We would like to further suggest that the compelling and novel imaging data provided in that study provides support for a sensory source for the increase in Stroop interference after TBI Schneider 2009, 2010;Ben-David et al 2011, 2014.

The color word Stroop test is the most commonly used tool to assess selective-attention in TBI.

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“…The classic Stroop test includes at least two tasks: (1) Naming the font color of a stimulus unrelated to color (dot color naming condition in Plenger et al 2015; baseline condition); and (2) Naming the font color of a color-word, where the semantic content is mismatched with the print color -e.g., the word RED printed in blue (incongruent condition in Plenger et al 2015). The latency difference between the two tasks is referred to as the Stroop Interference (SI).…”