Prefrontal cortex activity during binocular color fusion and rivalry: an fNIRS study

Xiang Liu ^1,2,3 Xuesong Jin ^2,3 Lijun Yun ^2,3 Zaiqing Chen ^1,2,3,4*

• ¹ Yunnan Key Laboratory of Optoelectronic Information Technology, Kunming, Yunnan Province, China
• ² Yuxi Key Laboratory of Mental Health Examination, Yuxi, China
• ³ Engineering Research Center of Computer Vision and Intelligent Control Technology, Department of Education of Yunnan Province, Kunming, Yunnan Province, China
• ⁴ School of Information Science and Technology, Yunnan Normal University, Kunming, China

Understanding how the brain processes color information from both the left and right eyes is a significant topic in neuroscience. Binocular color fusion and rivalry, which involve advanced cognitive functions in the prefrontal cortex (PFC), provide a unique perspective for exploring brain activity. This study used functional near-infrared spectroscopy (fNIRS) to examine PFC activity during binocular color fusion and rivalry conditions. The study included two fNIRS experiments: Experiment 1 employed longduration (90 seconds) stimulation to assess brain functional connectivity, while Experiment 2 used short-duration (10 seconds) repeated stimulation (8 trials), analyzed with a generalized linear model to evaluate brain activation levels. Statistical tests were then conducted to compare the differences in brain functional connectivity strength and activation levels. The results indicated that functional connectivity strength was significantly higher during the color fusion condition than the color rivalry condition, and the color rivalry condition was stronger than the Mid-Gray field condition. Additionally, brain activation levels during binocular color fusion were significantly greater, with significant differences concentrated in channel (CH) 12, CH13, and CH14. CH12 is located in the dorsolateral prefrontal cortex, while CH13 and CH14 are in the frontal eye fields, areas associated with higher cognitive functions and visual attention. These findings suggest that binocular color fusion requires stronger brain integration and higher brain activation levels. Overall, this study demonstrates that color fusion is more cognitively challenging than color rivalry, engaging more attention and executive functions. These results provide theoretical support for the development of color-based brain-computer interfaces and offer new insights into future research on the brain's color-visual information processing mechanisms.