Early Taste Experiences Drive Neural Responsiveness and Plasticity in Gustatory Cortex Circuits

Vignesh Subramanian ’24

Figure 1: A mouse drinking from a sipper tube. 

An individual’s taste preference strongly influences their food choice, impacting their diet and, in turn, their health. Taste preference is defined as an individual’s partiality towards a particular food based on their sensory perception of its taste modalities (sweet, sour, salty, bitter, etc.), flavor, texture, and a host of other factors, and is in part guided by early experiences that identify foods as pleasurable or metabolically useful to consume. Taste preference is modulated by the gustatory portion of the insular cortex of the human brain, which processes input from taste buds on the tongue by ascribing both hedonic and utility-based value to the given food. However, the nature of how gustatory experiences influence the rewiring of cortical circuits to establish distinct taste preferences has not been previously examined. Researchers at Stony Brook University led by Dr. Schiff thus worked to characterize the relationship between gustatory experience and the function of these circuits. 

The researchers first developed a taste exposure paradigm to assess taste experience, giving trained weanling mice access to four different solutions on an eight-day schedule: one sweet (sucrose), one sour (citric acid), one salty (salt), and another that was sweet but less so than sucrose (Ensure supplement). These solutions collectively simulated an “early exposure” (EE) setting in which the young mice could begin differentiating between solution tastes. The researchers then conducted a brief access test to determine the relationship between EE and sweet preference and swapped out specific tastants for others of identical taste modalities to see if the preferences held. Finally, two-photon imaging, patch clamping, and slice preparations were derived from both naive (control group) and EE mice to compare their baseline neural activity with sweet taste-evoked responses in gustatory cortex (GC) neurons. 

The researchers found that, overall, “early exposure” taste experience establishes a distinct sweet preference in adult mice and strongly modulates postnatal GC circuit development. A significant degree of chemosensation (the convergence of sensory and ingestive signals creating an organism’s perception of a substance’s nutritional content and palatability) was found to determine the rate at which such preferences were established. Furthermore, increased activity of parvalbumin-expressing (PV+) neurons and reduced activity in pyramidal (PYR) neurons (the excitatory neuron)— both located in the GC— were found to regulate the EE mice’s particular responsiveness to sucrose. Collectively, these findings demonstrate the extensive, long-term interplay between experience-dependent changes in preference and GC circuit plasticity. 

Works Cited:
[1] H. Schiff, et al., Experience-dependent plasticity of gustatory insular cortex circuits and taste preferences. Science Advances 9, 1-19 (2023). doi: 10.1126/sciadv.ade6561

[2] Image retrieved from: https://www.peakpx.com/606682/mouse-drinking-water


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