Prefrontal Cortex Activity During the N-Back Tasks in High and Low Sensitivity Groups: An fNIRS Study

• In Event: Environmental Sensitivity in School Children: Understanding Cognitive Empathy, Memory and Behavior of Highly Sensitive Children

Abstract

Introduction: The theoretical basis for this research is the concept of Environmental Sensitivity, a meta-framework for theories explaining individual differences in the ability to perceive and process environmental stimuli. One of them is the concept of Sensory Processing Sensitivity (SPS) which assumes that temperamental traits play a key role in these differences. Genetic factors involved in SPS, and temperament traits in general, interact with environmental factors to determine developmental trajectories that organize the brain and lead to individual differences in socio-emotional, behavioral, and cognitive adaptation. Research also shows that SPS is associated with differences in controlled and automatic attention neural processes that have implications for other aspects of cognition (e.g.memory, creativity), with some being beneficial and some not. Accordingly, to address the question about prefrontal cortex activity while performing cognitive tasks, we use an n-back task (n ∈ {1, 2}) to induce different levels of cognitive load, asking students to continuously remember the last one (1-back), or two (2-back) of rapidly changing letters. In this study, we used functional Near-Infrared Spectroscopy (fNIRS) to measure hemodynamic responses in the brain cortex.
Sample: A total of 27 students aged 11-13 (M=12; SD=0,82) with different sensitivity levels were included in the study. The tool used to evaluate their sensitivity was the Highly Sensitive Child Scale. Extreme groups of low (n=12, 8 girls, 4 boys) and high sensitivity (n=15; 10,5) were selected. The following factors were analyzed in an ANOVA: Chromophore (oxy vs. dexy-Hb), N-back (N1 vs. N2), Channel (16 fNIRS channels), and Group (low vs. high sensitivity).
Hypothesis: It was hypothesized that high- and low-sensitivity children would have different levels of oxy-Hb and deoxy-HB during n-back tasks indicating their different reactions to cognitive load.
Results: The results indicate a significant interaction of the factors Group * Chromphore * Channel F (1.15) = 1.756; p = 0.04; ηp 2= 0.07. The channels in the central areas (midline frontal gyrus, MFG) and those on the right and left sides (dorsal lateral prefrontal cortex, DLPFC) were subsequently checked with contrasts. Children from the low sensitivity group (LSC) had significantly higher levels of oxy-Hb than children from the high sensitivity (HSC) group in the "DLFPC" areas (in channels 3, 4, 13). Moreover, children in group LSC also had significantly higher Hb deoxy levels in channel 8, located in the central part ('MFG'). The obtained results may support the assumption that the HSC were more overwhelmed by the task and less focused than the low-sensitive children. On the other hand, they put less cognitive effort into the task itself and were distracted faster. However, this may also mean that they had no great difficulty in completing the task. It was easier for LSC to focus on the task and to engage them attentively. The results require further analysis in terms of the effects on task performance.

Authors

• Monika Baryła-Matejczuk, WSEI University
  Presenting Author

• Dariusz Zapała, The John Paul II Catholic University of Lublin

• Robert Porzak, WSEI University

• Pawel Augustynowicz, The John Paul II Catholic University of Lublin