All of us read other people’s faces and we all depend on it particularly to identify them and to understand how they feel. A new study shows that how we look at each others’ faces may be controlled by our genetic makeup, especially the cannabinoid receptor (CNR1) gene. The study was conducted by Dr. Chakrabarti and Professor Simon Baron-Cohen at the University of Reading and the University of Cambridge respectively and has recently been published in BioMed Central’s open-access journal Molecular Autism.

This new research may be of value in understanding the atypical gaze in people suffering from autism spectrum conditions (ASC). ASC is a spectrum of psychological conditions characterized by widespread abnormalities of social interactions and communication, as well as restricted interests and repetitive behavior. The results of this study show that variations of the cannabinoid receptor (CNR1) gene (a gene that modulates striatal responses to happy faces) can alter the amount of time people spend looking at happy faces.

Previous research conducted by the authors had demonstrated that mutations that occur naturally in the CNR1 gene were linked to a modified activity in the region of the brain involved in emotion and reward behavior in response to happy faces.

In the new research the authors selected 28 adult volunteers and collected DNA samples for analyses. A ‘gaze tracker’ was used to test the duration for which the volunteers looked at eyes and mouths of faces in video clips shown to them. All faces had different emotions. The scientists found that variations within two of the four naturally occurring mutations in CNR1 gene corresponded to longer gaze at happy faces but not with faces that were repulsive. Both these areas in the CNR1 gene involved for happy faces were found to be within a portion of the DNA that may be responsible for regulating the production of protein.

Dr Chakrabarti stated:

“This is the first study to have shown that how much we gaze at faces is influenced by our genetic make-up. If replicated it has profound implications for our understanding of the drive to socialize, and in turn, the atypical use of gaze in autism”.

Conclusions

In this study the researchers tested the modulations in gaze duration towards happy faces with respect to variations in CNR1 gene and found that two SNPs were considerably linked with gaze duration for happy faces. The results were found to be consistent with that of the fMRI study conducted by the same researchers previously.

The allelic groups associated with strongest striatal response in the fMRI study were associated with the longest gaze duration for happy faces in the current study sample. These results conclude that CNR1 gene plays a role in social reward processing and may be significant for clinical conditions such as ASC which are marked by atypical responses to facial expressions of emotion.

Abbreviations – CNR1 – cannabinoid receptor 1; mRNA, messenger RNA; SNP, single-nucleotide polymorphism.

“Variation in the human cannabinoid receptor CNR1 gene modulates gaze duration for happy faces”
Bhismadev Chakrabarti and Simon Baron-Cohen
Molecular Autism Written by Barry Windsor