Functional magnetic resonance imaging (fMRI) has been used to unveil how consumption of certain foods and other basic rewards are processed within the human brain, but traditional fMRI has not been widely used to investigate neural stimulation of consuming solid foods, because of potential safety hazards and poor imaging quality. Novel scanning methods could alleviate this.
Resting state fMRI scans allow for administration of a stimulus before scanning, and literature has shown resting state networks reflect functional connectivity between brain regions. Resting state scans show functional connectivity by correlating active neurons across the brain.
Similar to processing other rewards, we believe that hedonic circuits in the consumers’ brain will be activated while eating steak. Traditional sensory evaluation allows researchers to evaluate attributes that affect preferences of products as well as purchase decisions, incorporation of neuroimaging could show a neural perspective of why certain stimuli are processed in that manner.
The objective of this experiment was to evaluate functional connectivity to various structures in the brain after consuming high and low qualities of steak. Resting state scans of trained participants (n=8) were taken before, directly after and after an extended time (25 to 30 minutes) of receiving samples. High-quality steaks were Prime grade and aged for 35 days. Low-quality steaks were not aged and were previously rated lowest by consumers evaluating overall liking. Resting state scans showed connectivity to the left and right amygdala as well as the left and right anterior insula. These regions were selected a priori due to their integral nature in processing flavor. Participants were re-scanned on a separate day when eating the opposite quality steak. Blood oxygen level dependant imaging displayed hemodynamic fluctuation through the brain during fMRI procedures. Initial images were taken in the scanner before consumption. Participants left the scanning room to eat their sample, and marked a 6 in anchored visual analog scale (VAS) as a subjective evaluation of tenderness, juiciness, flavor and overall liking. The VAS was anchored as terrible, very poor, poor, fair, good, very good and excellent, at 0, 1, 2, 3, 4, 5 and 6 in, respectively. After re-entry scans were taken as soon as possible and participants cleansed their palates in a separate room before undergoing a final resting state scan.
Imaging data showed high-quality steak resulted in significantly greater functional connectivity between the left and right anterior insula as well as the left and right amygdala to the striatum, medial orbitofrontal cortex and insular cortex directly after consumption. There was also significantly greater functional connectivity between the left and right anterior insula as well as the left and right amygdala to the striatum, orbitofrontal cortex and hippocampus an extended time after consumption. High-quality steak was perceived superior for each palatability trait, having mean VAS measurements of 5.53, 5.29, 5.62 and 5.48 in for tenderness, juiciness, flavor and overall liking, respectively. Low-quality steak had mean VAS measurements of 1.94, 1.95, 1.93 and 2.07 in for tenderness, juiciness, flavor and overall liking, respectively. Together, these results suggest resting state fMRI may be useful for evaluating neural processes consumption of steak.
This novel technique has potential to bring new methods of sensory evaluation of meat products that incorporate neuroimaging. In recent years there have been numerous advances in neural topography, and this research adds knowledge and understanding about neural responses to hedonic stimuli. Other neuroimaging techniques may also be useful to better understand how consumers process information about meat that is consumed. We plan to continue mapping responses of consumers with additional neuroimaging studies. NP
