Navigating a diversity of turbulent plumes is enhanced by sensing complementary temporal features of odor signals

We and others have shown that during odor plume navigation, walking Drosophila melanogaster bias their motion upwind in response to both the frequency of their encounters with the odor (Demir et al., 2020), and the intermittency of the odor signal, i.e. the fraction of time the signal is above a detection threshold (Alvarez-Salvado et al., 2018). Here we combine and simplify previous mathematical models that recapitulated these data to investigate the benefits of sensing both of these temporal features, and how these benefits depend on the spatiotemporal statistics of the odor plume. Through agent-based simulations, we find that navigators that only use frequency or intermittency perform well in some environments – achieving maximal performance when gains are near those inferred from experiment – but fail in others. Robust performance across diverse environments requires both temporal modalities. However, we also find a steep tradeoff when using both sensors simultaneously, suggesting a strong benefit to modulating how much each sensor is weighted, rather than using both in a fixed combination across plumes.

Odor habituation can modulate very early olfactory event-related potential

Odor habituation is a phenomenon that after repeated exposure to an odor, is characterized by decreased responses to it. The central nervous system is involved in odor habituation. To study odor habituation in humans, measurement of event-related potentials (ERPs) has been widely used in the olfactory system and other sensory systems, because of their high temporal resolution. Most previous odor habituation studies have measured the olfactory ERPs of (200–800) ms. However, several studies have shown that the odor signal is processed in the central nervous system earlier than at 200 ms. For these reasons, we studied whether when odors were habituated, olfactory ERP within 200 ms of odors could change. To this end, we performed an odor habituation behavior test and electroencephalogram experiments. In the behavior test, under habituation conditions, odor intensity was significantly decreased. We found significant differences in the negative and positive potentials within 200 ms across the conditions, which correlated significantly with the results of the behavior test. We also observed that ERP latency depended on the conditions. Our study suggests that odor habituation can involve the olfactory ERP of odors within 200 ms in the brain.

Interpreting the Spatial-Temporal Structure of Turbulent Chemical Plumes Utilized in Odor Tracking by Lobsters

Olfactory systems in animals play a major role in finding food and mates, avoiding predators, and communication. Chemical tracking in odorant plumes has typically been considered a spatial information problem where individuals navigate towards higher concentration. Recent research involving chemosensory neurons in the spiny lobster, Panulirus argus, show they possess rhythmically active or ‘bursting’ olfactory receptor neurons that respond to the intermittency in the odor signal. This suggests a possible, previously unexplored olfactory search strategy that enables lobsters to utilize the temporal variability within a turbulent plume to track the source. This study utilized computational fluid dynamics to simulate the turbulent dispersal of odorants and assess a number of search strategies thought to aid lobsters. These strategies include quantification of concentration magnitude using chemosensory antennules and leg chemosensors, simultaneous sampling of water velocities using antennule mechanosensors, and utilization of antennules to quantify intermittency of the odorant plume. Results show that lobsters can utilize intermittency in the odorant signal to track an odorant plume faster and with greater success in finding the source than utilizing concentration alone. However, the additional use of lobster leg chemosensors reduced search time compared to both antennule intermittency and concentration strategies alone by providing spatially separated odorant sensors along the body.

Kompleksitas Obyek dan Running-Wheel Mempengaruhi Novel Object Recognition Test pada Mencit (Mus musculus)

This research aimed to confirm the tendency of mice to novel object, effect of exercise (in running-wheel) toward memory of mice and to test tendency of mice in avoiding predator signal in novel object. Novel object recognition test (NORT) used to test the memory the day after acquisition phase (NORT I) and memory one week after exercise was given (running-wheel) (NORT II). The result showed that there was no tendency of mice in exploring toward novel object in both NORT I and NORT II. This might happen because the complexity of familiar object higher than novel object, so the familiar object could accommodate more activities. Exercise using running-wheel in mice had an effect on memory, it could be seen in decreasing duration of object exploration time from NORT I to NORT II. There was no tendency in avoiding predator’s signal on novel object which was attached by urine addition (odor signal).

Coordinated Plasticity between Barrel Cortical Glutamatergic and GABAergic Neurons during Associative Memory

Neural plasticity is associated with memory formation. The coordinated refinement and interaction between cortical glutamatergic and GABAergic neurons remain elusive in associative memory, which we examine in a mouse model of associative learning. In the mice that show odorant-induced whisker motion after pairing whisker and odor stimulations, the barrel cortical glutamatergic and GABAergic neurons are recruited to encode the newly learnt odor signal alongside the innate whisker signal. These glutamatergic neurons are functionally upregulated, and GABAergic neurons are refined in a homeostatic manner. The mutual innervations between these glutamatergic and GABAergic neurons are upregulated. The analyses by high throughput sequencing show that certain microRNAs related to regulating synapses and neurons are involved in this cross-modal reflex. Thus, the coactivation of the sensory cortices through epigenetic processes recruits their glutamatergic and GABAergic neurons to be the associative memory cells as well as drive their coordinated refinements toward the optimal state for the storage of the associated signals.

Design of a Bionic Olfactory, Tactile Integrated System and its Application in Chicken Meat Quality Inspection

This study is aiming at the practical problem of meat freshness evaluation. Since meat putrefaction is a complex process that is influenced by many factors, it is necessary to have a comprehensive investigation of the various indicators to determine the freshness of meat. This research integrated information from a multisensory system to reduce uncertainty of evaluation. According to the odor mechanism model of rotten chicken, six types of sensors were chosen, which were combined as array for olfactory experiments. WDW-20 electronic universal testing machine (UTM) was adopted as tactile sensing device. As a bionic tactile test part, the UTM head is to obtain pressure characteristic curves of the meat. According to the odor model and elastic mechanics parameters of the chicken, the mechanical parameters were analyzed under the condition of cold storage, as well as time-varying results of fingerprint odor signal and salt base nitrogen volatile signal. Then, established the meat odor, elastic mechanics and freshness parameters, which were integrated into a fusion system and combined with the data through the experimental test. Eventually, established the mathematical model among meat odor, elastic mechanics parameters and meat freshness. This study provides theory reference for the evaluation of meat freshness, and delivers new thought and method for the design of multiphase bionic intelligent electrical measuring equipment.