Abstract
The discrimination learning of multiple odors, in which multi-odor can be associated with different responses, is important for responding quickly and accurately to changes in the external environment. However, very few studies have been done on multi-odor discrimination by animal sniffing. Herein, we report a novel multi-odor discrimination system by detection rats based on the combination of 2-Choice and Go/No-Go (GNG) tasks into a single paradigm, in which the Go response of GNG was replaced by 2-Choice, for detection of toluene and acetone, which are odor indicators of lung cancer and diabetes, respectively. Three of six trained rats reached performance criterion, in 12 consecutive successful tests within a given set or over 12 sets with a success rate of over 90%. Through a total of 1300 tests, the trained animals (N = 3) showed multi-odor sensing performance with 88% accuracy, 87% sensitivity and 90% specificity. In addition, a dependence of behavior response time on odor concentrations under given concentration conditions was observed, suggesting that the system could be used for quantitative measurements. Furthermore, the animals’ multi-odor sensing performance has lasted for 45 days, indicating long-term stability of the learned multi-odor discrimination. These findings demonstrate that multi-odor discrimination can be achieved by rat sniffing, potentially providing insight into the rapid, accurate and cost-effective multi-odor monitoring in the lung cancer and diabetes.
Highlights
Animals instinctively detect situations that threaten them
All animals were maintained under normal conditions with a 12-h light-dark cycle and were individually housed in transparent plastic cages with temperature and humidity adjusted to 25 ◦ C and 40% relative humidity (RH)
Multi-Odor Discrimination Device Based on the Combined 2-Choice/No-Go Paradigm
Summary
Animals instinctively detect situations that threaten them. Rodents, for example, use their strong sense of olfaction to recognize and avoid predators they have never seen before [1]. Some animals (i.e., dogs, rats, etc.) have superior olfactory discrimination abilities compared to humans. Such animals’ innate ability for odor detection and associative learning is the basis for animal nose biosensors [2,3]. Understanding for odor recognition has not yet been fully clarified at the molecular level, animals conditioned with odor stimuli can quickly and accurately recognize VOCs (volatile organic compounds) and exhibit alerting behaviors as specific signaling behaviors [4]. Animal nose sensors, which utilize animal’s olfactory ability to detect specific odors, are gaining increasing interest in the fields of forensics and homeland security due to their cost efficiency and excellent detection performance [5,6], and has been mainly applied to drug detection [7,8]
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