Genetic Analyses of Perceptual Rivlary



What do you see in this picture? A vase or two faces?

After a period of time, you will find that sometimes you see a white vase in the middle and sometimes you see two black faces on the sides. The image you see will switch spontaneously between the vase and the faces, but at any given moment, you can only see one of them.

This switching is neither due to changes of the image, nor due to changes in your eyes because the physical stimuli received by the retina is constant.

How does this switching happen? The simple answer is that it is your brain: it is the perception by the brain that switches.

This interesting visual cognition phenomenon is called bistable visual perception. In addition to the face-vase switch, other well-known examples of bistable perception include the Necker cube (the middle image below): the cube can be seen as facing towards the upper-left (the left image below) or towards the lower-right (the right image below) due to lack of depth information.



When each of our eyes was presented with a different visual stimulus, our brain's perception will stay at one eye's image for a few seconds and then be replaced by the image of the other eye, and keep switching back and forth thereafter. Both eyes strive to make the image stimulus it receives dominate the perception in the brain. This phenomenon is vividly called " binocular rivalry".




Bistable visual perception was scientifically and systematically described by the researcher Necker in 1832, taking the Necker cube as an example(1). In 1838, Charles Wheatstone, another researcher, made the first systematic study of binocular rivalry, another branch of visual perception rivalry, using a self-made stereoscope(2).

Perceptual rivalry can be voluntarily modulated by the brain's top-down control(3,4). There are huge individual differences in human perceptual switching rate and voluntary modulation strength. Some patients with psychiatric disorders (such as bipolar disorder and autism) show different rivalry patterns(5-9) from normal people, in terms of perceptual switching rate and duration in each perceptual state. Therefore, investigating the biological basis of perceptual rivalry may help us to find biomarkers for certain psychological disorders(10). Cognitive science research on human visual perceptual rivalry and its voluntary modulation has long been relying on psychological behavioral experiments and brain imaging including electroencephalography, magnetoencephalography, and brain magnetic resonance imaging (MRI)(11-13), whereas genetic studies have been rare.


Recently, Biqing Chen, Zijian Zhu, Ren Na and others from the laboratories of Drs. Yi Rao and Fang Fang at Peking University, have performed a systematic study on perceptual switching behavior and voluntary control in nearly 3400 Chinese Han college students. They chose two experimental paradigms of visual perception rivalry: the classic Necker cube rivalry and the binocular rivalry based on red-blue stereoscope, and they explored the top-down influence by the brain on the perceptual switching rate of Necker cube rivalry. By analyzing the behavioral and genomic data of these subjects, they found that human spontaneous perceptual switching rate has a heritability of about 25%, providing a genetic basis for using perceptual switching rate as a potential biomarker of mental disorders. They then carried out a genome-wide association study (GWAS) at multiple levels in a large sample of 2441 and replicated the results in another cohort of 943 subjects. They discovered that PRMT1, OR11A1, OR1L6 and other genes were associated with spontaneous perceptual switching rate, while single nucleotide polymorphisms including rs184765639, rs7559941, and genes such as MIR1178 were related to voluntary modulation strength(14). Further brain structural MRI experiments revealed genotypic difference of rs184765639 in the surface area of the left caudal-middle frontal cortex. Interestingly, although there are a small number of associated genes and pathways shared by binocular rivalry and Necker cube rivalry, the correlation between the two different perception rivalry paradigms was not high (the correlation coefficient is less than 0.3), indicating different perceptual rivalry paradigms might have distinct biological mechanisms.

Their paper titled “Genomic analyses of visual cognition: perceptual rivalry and top-down control” was published online in the Journal of Neuroscience on September 21th, 2018. The Rao and Fang laboratories cooperated in exploring the biological basis of human visual cognitive behaviors using genomic research methods. This is their first collaborative paper, combining expertise in genetic analyses expertise of Rao lab with that in the visual cognitive research expertise of Fang lab. Chongqing Medical University participated in this collaborative project.

The Rao lab has recently studied molecular basis of human cognition. The latest genome-wide association study of visual perceptual rivalry is their fourth published study on human cognition and their third paper on genetic analysis of human cognition. Their first article was published in the journal Cognition in 2016 by Zijian Zhu and others on human memory interference and reconsolidation mechanism(15), with Dr.s Yi Rao and Yanhong Wu from the Department of Psychology as co-corresponding authors. The second paper is a GWAS on human social conformity published in 2018 in the Journal of Human Genetics by Biqing Chen et al(16), with Yi Rao as the corresponding author; the third paper was published in the European Journal of Human Genetics by Zijian Zhu, Biqing Chen and others in 2018, studying the genetics of human memory using GWAS approach(17), and doctoral graduates Zijian Zhu and Biqing Chen of the Rao lab were the corresponding authors. The corresponding authors of the latest Journal of Neuroscience paper were Professors Yi Rao and Fang Fang from the PKU-IDG/McGovern Brain Research Institute, with Drs. Biqing Chen and Zijian Zhu from the Rao lab, and Dr. Ren Na from the Fang lab as the co-first authors.




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15. Chen BQ, Zhu ZJ, WangYY, DingXH, GuoXB, He MG, FangW, ZhouSB, ZhouQ, HuangAL, ChenTM, NiDS, GuYP, LiuJN, Lei H, RaoY (2018). Nature vs. nurture in human sociality: multi-level genomic analyses of social conformity. J Hum Genet 63:605-619.
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