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Recent Advances in Taste and Smell Research
- The body uses chemosensory transduction mechanisms—processes that enable the conversion of detection into an electrical signal—throughout the oral and nasal cavities. These transduction mechanisms play a major role in the regulation of food intake and the protection of the airways. Scientists have discovered new families of chemosensory receptors (trace amine-associated receptors, formyl peptide receptors) that could detect chemical cues used for communication of odors that signal disease.120
- Scientists have discovered new chemosensory receptors and transduction mechanisms in the gustatory (taste)121-126 and olfactory systems.127, 128
- Scientists are using novel single cell techniques to make numerous copies of the DNA expressed in a single cell as it progresses through early development to explore how olfactory receptor cells choose which receptor to express.129
- Bacteria release quorum signaling molecules to coordinate behaviors such as biofilm formation, virulence, and antibiotic resistance, based on the local density of the bacterial population. Taste receptors expressed in solitary chemosensory cells and ciliated cells of the respiratory epithelium detect irritants and quorum signaling molecules of pathogenic bacteria, evoking protective airway reflexes and inflammatory responses to rid the airways of infection.130, 131
- The use of novel methods132 is rapidly expanding our identification of the ions or molecules (ligands) that bind to a receptor for the diverse set of identified chemosensory receptors.133-136
How Genes and Environment Affect Food Preference
- Experience, internal state, and genetic variation in taste and smell receptor genes affect chemosensory likes and dislikes.137-143 Thus, the chemical senses play key roles in the regulation of food intake that underlies major health issues such as obesity and diabetes.144-146
- The discovery that children and adults experience chemical senses differently has broad implications for the role of flavor in diet selection and health across the lifespan as well as for basic research into the organization and maintenance of chemosensory pathways.147
Chemical Senses and Disease
- Some heritable diseases (e.g., channelopathies and ciliopathies)148-150 as well as neurodegenerative diseases (e.g., Alzheimer’s disease)151-153 have a correlated chemosensory dysfunction that scientists may use to help diagnose diseases or gauge the effectiveness of treatment.
- Individuals who inherit genes that code for one particular version of a bitter taste receptor (a genetic polymorphism) are more susceptible to chronic rhinosinusitis.154 New genetic models of this condition may lead to novel therapeutic interventions for the associated olfactory deficits.155
- Radiation, chemotherapy and traumatic head injuries severely disrupt chemosensory function. Basic research into signaling pathways and transcription factors that regulate development and turnover of chemosensory cells provides a potential basis for restoring chemosensory function.156-161
- Understanding invertebrate chemoreceptor mechanisms and sensitivities162-164 has opened avenues for control and prevention of critical insect-borne diseases such as malaria, dengue fever, encephalitis, and Zika.
- By understanding how taste and smell signaling is set up during normal development, we have a better chance of figuring out how to repair this signaling process if it is damaged. Information about how taste and smell are interpreted in the brain and influence behavior may also be useful for helping us understand why certain tastes and smells make us behave in certain ways, and could help us develop ways to improve mood and modify behavior by modifying this response. Scientists have learned a lot about the cortical circuits that process taste and smell, including:
- Scientists better understand the divisions of function in cortical structures that interpret chemical senses information165-171 and how these circuits fail in pathology.135, 172
- They are learning how cortical circuits create and read odor patterns and the basic circuitry and physiology of these circuits.173-176
- They are using artificial neural networks and optical imaging to define and dissect the circuitry and coding in the chemical senses.177-181
- They have figured out how adult-born neurons can be functionally and synaptically integrated into neural circuits.182
- They have better insight into how activity within these neural circuits translates to chemosensory perception and stimulus identification171, 183-188 and guide such behaviors as emotional response189 and parenting behavior.190
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