A comparative analysis of animal behavior (e.g., male vs. female groups) has been widely used to elucidate behavior specific to one group since pre-Darwinian times. However, big data generated by new sensing technologies, e.g., GPS, makes it difficult for them to contrast group differences manually. This study introduces DeepHL, a deep learning-assisted platform for the comparative analysis of animal movement data, i.e., trajectories. This software uses a deep neural network based on an attention mechanism to automatically detect segments in trajectories that are characteristic of one group. It then highlights these segments in visualized trajectories, enabling biologists to focus on these segments, and helps them reveal the underlying meaning of the highlighted segments to facilitate formulating new hypotheses. We tested the platform on a variety of trajectories of worms, insects, mice, bears, and seabirds across a scale from millimeters to hundreds of kilometers, revealing new movement features of these animals.

To survive a predator’s attack successfully, animals choose appropriate actions from multiple escape responses. The motor performance of escape response governs successful survival, which implies that the action selection in escape behaviour is based on the trade-off between competing behavioural benefits. Thus, quantitative assessment of motor performance will shed light on the biological basis of decision-making. To explore the trade-off underlying the action selection, we focused on two distinct wind-elicited escape responses of crickets, running and jumping. We first hypothesized a trade-off between speed and directional accuracy. This hypothesis was rejected because crickets could control the escape direction in jumping as precisely as in running; further, jumping had advantages with regard to escape speed. Next, we assumed behavioural flexibility, including responsiveness to additional predator’s attacks, as a benefit of running. The double stimulus experiment revealed that crickets running in the first response could respond more frequently to a second stimulus and control the movement direction more precisely compared to when they chose jumping for the first response. These data suggest that not only the motor performance but also the future adaptability of subsequent behaviours are considered as behavioural benefits, which may be used for choosing appropriate escape reactions.

Cyclic guanosine monophosphate (cGMP) plays a crucial role as a second messenger in the regulation of sensory signal transduction in many organisms. In AWC olfactory sensory neurons of , cGMP also has essential and distinctive functions in olfactory sensation and adaptation. According to molecular genetic studies, when nematodes are exposed to odorants, a decrease in cGMP regulates cGMP-gated channels for olfactory sensation. Conversely, for olfactory adaptation, an increase in cGMP activates protein kinase G to modulate cellular physiological functions. Although these opposing cGMP responses in single neurons may occur at the same time, it is unclear how cGMP actually behaves in AWC sensory neurons. A hypothetical explanation for opposing cGMP responses is region-specific behaviors in AWC: for odor sensation, cGMP levels in cilia could decrease, whereas odor adaptation is mediated by increased cGMP levels in soma. Therefore, we visualized intracellular cGMP in AWC with a genetically encoded cGMP indicator, cGi500, and examined spatiotemporal cGMP responses in AWC neurons. The cGMP imaging showed that, after odor exposure, cGMP levels in AWC cilia decreased transiently, whereas levels in dendrites and soma gradually increased. These region-specific responses indicated that the cGMP responses in AWC neurons are explicitly compartmentalized. In addition, we performed Ca imaging to examine the relationship between cGMP and Ca These results suggested that AWC sensory neurons are in fact analogous to vertebrate photoreceptor neurons. Cyclic guanosine monophosphate (cGMP) plays crucial roles in the regulation of sensory signal transduction in many animals. In AWC olfactory sensory neurons of , cGMP also has essential and distinctive functions involving olfactory sensation and adaptation. Here, we visualized intracellular cGMP in AWC neurons with a genetically encoded cGMP indicator and examined how these different functions could be regulated by the same second messenger in single neurons. cGMP imaging showed that, after odor application, cGMP levels in cilia decreased transiently, whereas levels in dendrites and soma gradually increased. These region-specific responses indicated that the responses in AWC neurons are explicitly compartmentalized. In addition, by combining cGMP and Ca imaging, we observed that AWC neurons are analogous to vertebrate photoreceptor neurons.

No abstract

No abstract