Published in Chemical Sensors, Hao Jia, O. Pustovyy, G. Deshpande, and colleagues investigated whether zinc nanoparticles can amplify odor-evoked brain activity in dogs. Canine olfaction is already highly sensitive, yet improving detection at extremely low concentrations remains a key goal for applications such as explosives and contraband detection.
Using noninvasive in vivo functional magnetic resonance imaging (fMRI), the researchers examined brain responses to odorants presented alone and mixed with zinc nanoparticles. To image fully conscious and unrestrained dogs, the team combined behavioral training with optical motion tracking to minimize head-motion artifacts, enabling reliable neural measurements without anesthesia.
Brain activation maps were obtained from dogs in both anesthetized and fully conscious states. The results demonstrated that the enhancement effect of zinc nanoparticles was markedly stronger in conscious dogs, with increased activation not only in primary olfactory regions but also in higher-order brain areas.
In conscious dogs, significantly greater activity was observed in the olfactory bulb and hippocampus when odorants were mixed with zinc nanoparticles compared with pure odorants, odorants mixed with gold nanoparticles, or zinc nanoparticles alone. These regions have been implicated in odor intensity processing in other species, including humans.
The comparison with anesthetized dogs highlighted that anesthesia substantially dampens higher-order neural responses, underscoring the importance of studying awake canine brains to understand real-world sensory processing.
The authors conclude that if these in vivo neural enhancement effects are confirmed by future behavioral studies, zinc nanoparticles may offer a method for increasing canine olfactory sensitivity. Such an approach could improve the performance of detection dogs by enabling recognition of target substances at concentrations that would otherwise go undetected.
Jia, H., Pustovyy, O., Deshpande, G., et al. (2016). Enhancement of Odor-Induced Activity in the Canine Brain by Zinc Nanoparticles: A Functional MRI Study in Fully Unrestrained Conscious Dogs. Chemical Sensors, published 2016.
