MedicalResearch.com Interview with:
Dr. Casey Trimmer, PhD
Geneticist, was a post-doctoral fellow at the
Monell Center when the research was conducted
MedicalResearch.com: What is the background for this study?
Response: We detect odors using 400 different types of sensor proteins, called olfactory receptors, in our noses. An odor molecule activates a specific combination of these receptors, and this pattern of activation gives us information on what we’re smelling–whether its floral or smoky, intense or weak, and how much we like it. However, how the system translates receptor activation to these perceptual features is largely unknown. Here, we take advantage of the extensive genetic variation in the OR gene family to understand the contribution of individual ORs to odor perception. By studying cases where the function of a particular OR is lost, we can examine what kinds of perceptual alterations occur, allowing us to link receptor to odor and understand what kind of information the receptor is encoding.
Data linking genetic variation to perceptual changes exist for only 5 ORs. Here, we examined the perceived intensity and pleasantness of 68 odors in 332 participants. We used next-generation genome sequencing to identify variants in 418 OR genes and conducted a genetic association analysis to relate this variation to differences in odor perception. We then use a cell-based assay to examine receptor function and investigate the mechanisms underlying our associations. Finally, we examined the contribution of single OR genotype, genetic ancestry, age, and gender to variations in odor perception.
MedicalResearch.com Interview with:
Ben Gold, a PhD candidate
Lab of Robert Zatorre
The Neuro (Montreal Neurological Institute and Hospital)
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: Music is just sound in air, but it carries considerable power. It captivates our brain’s reward system, we devote an enormous amount of time and money to it, and we’re just beginning to tap its therapeutic potential. We wanted to explore how something so abstract could have such an impact, and since music is so well suited to establishing and manipulating patterns of sound as it unfolds, we focused on how it manipulates expectations.
Previous research has shown that surprises are often the most emotional and pleasurable moments in music listening, but whether and how this engaged the brain’s reward system was unclear. So we adapted an experimental protocol designed for studying learning and surprise about more concrete rewards like food or money, and applied it to a musical context during brain imaging. This protocol relies on participants making decisions from which we could infer their expectations, allowing us to estimate how surprised they were by each outcome whenever it occurred. In our case, we asked participants to make choices about colors and directions that were associated with different musical outcomes, but we didn’t tell them what those associations were so that they they started with no expectations and learned as they went.
We found that our participants could learn about music just like they would learn about how to find food or win money, and that the same neural process was involved. Specifically, we saw that the activity of the nucleus accumbens — a central hub of the reward system — reflected both how pleasant and how surprising each musical outcome was: a computation known as a reward prediction error. Across individuals, those who better represented these reward prediction errors in their nucleus accumbens also learned better about the music in the experiment, making more decisions over time to find the music they preferred. Continue reading