From reversal to normal: Robust improvement in conflict adaptation through real-time functional near infrared spectroscopy-based neurofeedback training.

Conflict adaptation refers to the improved conflict control induced after experiencing conflict and is a prominent index of adaptive cognitive control. Reversal of conflict adaptation may be maladaptive and predictive of certain mental disorders. Here, we employed real-time functional near infrared spectroscopy-based neurofeedback training, with the left dorsolateral prefrontal cortex as the target brain area, to investigate whether reversal of conflict adaptation during a word-color Stroop task could be recovered to be normal. Healthy human individuals with reversal pattern of conflict adaptation in the pretest were randomly assigned into the experimental or control groups. Distributed training for 80 min led to greater improvements in the experimental group who received real neurofeedback compared to those in the control group who received sham neurofeedback. These results indicated causal evidence for understanding the generation of conflict adaptation and heighten the prospects of clinical application of neurofeedback training.

Alertness function of thalamus in conflict adaptation.

Conflict adaptation reflects the ability to improve current conflict resolution based on previously experienced conflict, which is crucial for our goal-directed behaviors. In recent years, the roles of alertness are attracting increasing attention when discussing the generation of conflict adaptation. However, due to the difficulty of manipulating alertness, very limited progress has been made in this line. Inspired by that color may affect alertness, we manipulated background color of experimental task and found that conflict adaptation significantly presented in gray and red backgrounds but did not in blue background. Furthermore, behavioral and functional magnetic resonance imaging results revealed that the modulation of color on conflict adaptation was implemented through changing alertness level. In particular, blue background eliminated conflict adaptation by damping the alertness regulating function of thalamus and the functional connectivity between thalamus and inferior frontal gyrus (IFG). In contrast, in gray and red backgrounds where alertness levels are typically high, the thalamus and the right IFG functioned normally and conflict adaptations were significant. Therefore, the alertness function of thalamus is determinant to conflict adaptation, and thalamus and right IFG are crucial nodes of the neural circuit subserving this ability. Present findings provide new insights into the neural mechanisms of conflict adaptation.

Feedback-related negativity effects vanished with false or monetary loss choice.

Feedback-related negativity (FRN) is sensitive to both monetary loss and evaluation of the correctness of a response. This study used a gambling task that required participants to choose between two cards that were unpredictably associated with monetary gains or losses. Feedback stimuli then indicated gain or loss, and the correctness of the participant's choice. Greater FRN amplitudes for loss versus gain conditions were observed when participants guessed correctly, as well as for incorrect versus correct conditions when they made gain choices. Conversely, FRN effects were absent after either false choices or those that led to losses. Therefore, FRN may reflect an interaction between guess correctness and the utilitarian value of feedback.

The effect of visual reliability on auditory-visual integration: an event-related potential study.

To investigate the neural mechanisms of auditory-visual integration, we recorded event-related potentials during a word-identification task, in which the stimulus was presented in the auditory (A), visual (V), and in the auditory-visual (AV) modalities. The reliability of the visual information varied at the high-reliability (VH) and low-reliability (VL) levels in both the V and AV presentations. The modulation of sensory integrations owing to the variation of cue reliability was revealed in the format of the double-difference waveform generated by subtracting the difference waveform AVL-(A+VL) from the difference waveform AVH-(A+VH). The results demonstrated (i) the early modulation of the activity in the auditory and visual cortex; (ii) subsequent spatial-temporal sequence of activities mostly occurred in multisensory areas; and (iii) the timing of final outputs of AV integration at around 370-410 ms poststimulus.

Detecting perceptual conflict by the feedback-related negativity in brain potentials.

The feedback-related negativity (FRN) in brain potentials is typically observed for the outcome evaluation concerning one's performance or monetary reward. Using a task in which the participant guesses whether the first stimulus (S1) would have the same color as the subsequently presented second stimulus (S2), this study demonstrates that the FRN to S2, which serves as feedback to the guessing, is also sensitive to the conflict between perceptual representations of S1 and S2 in working memory. The FRN effect for the feedback concerning the correctness of one's performance is modulated by the congruency between perceptual properties of the stimuli. The anterior cingulate cortex, which generates the FRN, is thus a general conflict-monitoring device detecting both response and perceptual conflicts.