Facial Expression Response Genotype-Phenotype Correlations in a Hands-On and Cross-Field Laboratory Experiment

Interdisciplinary research can simultaneously broaden student interest and improve creative thinking abilities. We designed a cross-field (Biology/Genetics, Psychology) laboratory-based teaching module running across two, 2&ndash;3-hour laboratory periods, that incorporates diverse molecular techniques and a novel phenotype assessment, as well as basic statistics and bioinformatics. Our module focuses on the human <em>CNR1</em> gene. Expression of <em>CNR1</em> in the brain and nervous system is one of many factors that may impact mood and cognition. <em>CNR1</em> variants have previously been correlated to striatal and visual response to images of happy faces. Using this work as a basis, we developed a relatively low-cost genotyping protocol for a common <em>CNR1</em> intron variant, including DNA extraction, PCR amplification, restriction enzyme digest, and gel electrophoresis. To assess students&rsquo; facial-recognition phenotypes, we developed a digital assessment to measure student response times to images of happy and angry faces. Compiling (anonymized) class data allows for the introduction of statistical testing, and basic bioinformatic investigation is applied to introduce students to NIH dbSNP, PCR primer design, and NCBI BLAST. Facial images in our phenotype assessment are drawn from the NimStim Database and are adjustable using this or similar resources or freely available artificial intelligence (AI)-based image generators, to reflect student ethnic/age/gender composition in individual school settings or to introduce students to additional diversity. This module has been run across four semesters of a junior-/senior-level undergraduate genetics laboratory course (average <em>ca.</em> 14 students/section), with consistent genotyping success. Included are student and teacher instructions for laboratory exercises, and online phenotype assessment resources. <em>Primary Image:</em> The human <em>CNR1 </em>locus carries a variant site (rs6454674) previously associated with neural response to images of happy faces. Two primary variants at this site can be distinguished by digestion with the <em>Tsp45I</em> restriction enzyme and subsequently tested for correlation to response times to happy and angry (against neutral) facial expressions.