Predicting affective valence using cortical hemodynamic signals

Figure 1. Distribution of classification accuracy values for negative vs. neutral (y-axes) and positive vs. neutral (x-axes) comparisons in the passive (a) and active (b) elicitation conditions. The diameter of the circle is proportional to the number of participants for which that level of performance was observed.

Figure 2. Weights assigned to the deoxyhemoglobin concentration of each channel by the linear discriminant analysis (LDA) classifier for passive elicitation decoding in positive vs. neutral (a) and negative vs. neutral (b) comparisons. Hotter colors are indicative of positive weights, while cooler colors are indicative of negative weights. Channels circled in red represent those with the highest absolute weights, while white letters indicate the corresponding subfigure that includes the block average for channels over the (c) left lateral orbitofrontal cortex (lOFC), (d) right lateral orbitofrontal cortex (lOFC), (e) dorsomedial prefrontal cortex (dmPFC), and (f) left dorsomedial prefrontal cortex (dmPFC). The continuous line represents the mean, while the shaded area represents the standard deviation, for positive (green), negative (red), and neutral (blue) affective experiences.

Figure 3. Weights assigned to the deoxyhemoglobin concentration of each channel by the linear discriminant analysis (LDA) classifier for active elicitation decoding in positive vs. neutral (a) and negative vs. neutral (b) comparisons. Hotter colors are indicative of positive weights, while cooler colors are indicative of negative weights. Channels circled in red represent those with the highest absolute weights, while white letters indicate the corresponding subfigure that includes the block average for channels over the (c) right medial orbitofrontal cortex (mOFC), (d) right lateral orbitofrontal cortex (lOFC), (e) right ventrolateral prefrontal cortex (vlPFC), and (f) left dorsomedial prefrontal cortex (dmPFC). The continuous line represents the mean, while the shaded area represents the standard deviation, for positive (green), negative (red), and neutral (blue) affective experiences.

Figure 4. Experimental design. Visual stimuli in passive elicitation condition (0–2 s: baseline; 2–37 s: target recording). Visual stimuli in active elicitation condition (0–2 s: baseline; 2–4 s: instruction; 4–34 s: target recording). Trial order was randomized across participants, with a neutral affective experience between negative and positive affective experiences.

Figure 5. Real, anatomical, and schematic representations of channel configuration in three different perspectives. Red circles represent sources, while blue circles represent detectors. Dotted lines represent channels. The remaining colors represent the regions of interest for each channel: yellow for the lateral orbitofrontal cortex (lOFC), green for the medial orbitofrontal cortex (mOFC), blue for the ventrolateral prefrontal cortex (vlOFC), pink for the dorsomedial prefrontal cortex (dmPFC), purple for the occipital/striatal cortex, and orange for the occipital/primary visual cortex. The participant in this figure provided written informed consent for the publication of his photo in an online open-access publication.