Frontal activation as a key for deciphering context congruity and valence during visual perception: An electrical neuroimaging study.

The object-context associations and the valence are two important stimulus attributes that influence visual perception. The current study investigates the neural sources associated with schema congruent and incongruent object-context associations within positive, negative, and neutral valence during an intermittent binocular rivalry task with simultaneous high-density EEG recording. Cortical sourceswere calculated using the sLORETA algorithm in 150 ms after stimulus onset (Stim + 150) and 400 ms before response (Resp-400) time windows. No significant difference in source activity was found between congruent and incongruent associations in any of the valence categories in the Stim + 150 ms window indicating that immediately after stimulus presentation the basic visual processing remains the same for both. In the Resp-400 ms window, different frontal regions showed higher activity for incongruent associations with different valence such as the superior frontal gyrus showed significantly higher activations for negative while the middle and medial frontal gyrus showed higher activations for neutral and finally, the inferior frontal gyrus showed higher activations for positive valence. Besides replicating the previous knowledge of frontal activations in response to context congruity, the current study provides further evidence for the sensitivity of the frontal lobe to the valence associated with the incongruent stimuli.

Altered functional connectivity: A possible reason for reduced performance during visual cognition involving scene incongruence and negative affect.

Object-context associations and valence are two unavoidable stimulus characteristics when it comes to the processing of natural visual scenes. In line with our previous studies exploring the parallel processing of context-congruity and valence, in the current study, we investigated the valence-specific differences in functional connectivity between congruent-incongruent picture pairs during binocular rivalry using high-density EEG. The functional connectivity measure was calculated using sLORETA during the perceptual dominance of congruent and incongruent stimuli in a time window of 400 ms before the response and compared within and between positive, negative, and neutral valence categories (84 Brodmann's areas across 7 frequency bands) using t-tests. A significant difference in functional connectivity between congruent-incongruent picture pairs was seen only when associated with negative valence and a maximum number of area pairs showed differences in lower alpha 1 (7.1-9 Hz), upper alpha (11.1-13 Hz), and beta (13.1-30 Hz) frequency bands. The functional connectivity was significantly lower during incongruent perception between the area pairs which process mainly emotion, attention, memory, and semantic relations compared to their corresponding congruent stimuli. Similarly, negative incongruent percepts were found to have significantly lower connectivity between areas processing attention, emotion, and incongruence in the lower alpha 2 (9.1 -11 Hz) band when compared to positive incongruent percepts. Together, these results suggest that the perception of negative incongruence is associated with lower functional connectivity and this could be a possible reason for the increased error rates when faced with incongruity and negative affect during visual tasks.