# Usage of a Sensory-Motor Intervention System for Understanding the Adaptive Behavior of Insets
## 3 Insect On-Board System
(**A**) Appearance of the system used in the experiments. (**B**) Method for adjusting spatial resolution in odor detection. (**C**) Coupling condition of sensory and motor output. (**D**) Localization success rate under each condition. The horizontal and vertical axes indicate elapsed time and localization success rate, respectively. The N-N condition shows the fastest and highest success rate of localization to the odor source, regardless of the spatial odor detection resolution. We performed the steel’s test on the success rate (*: \(p<0.05\), **: \(p<0.01\), ***: \(p<0.001\)). All data are licensed under CC-BY. For details of the discussion, we recommend reading the original paper [61]; however, the direction of movement was determined by estimating the local odor gradient using a bilateral odor input. Therefore, reversing the direction of olfactory input increased the likelihood of moving in the direction of low concentration, resulting in a larger proportion of exploratory behavior manifested by rotational movement than by straight-line movement. This may have reduced odor-tracking performance. On the other hand, the reversal of motion output not only causes the silk moth to move in an unintended direction, but also acts as positive visual feedback. This may further cause directional disorientation and decrease the success rate of localization. Recently, [PERSON] and [PERSON] extended the insect on-board system and investigated the performance of odor plume tracking when a delay occurred in the timing of sensory stimuli presented to silkworm moths [62]. The extended insect on-board system is almost the same as that of [PERSON] et al. However, the extended system is equipped with odor sensors and provides pheromone stimuli to a silk moth at the time of detection of the odor sensor. In other words, the silk moth can grasp the odor distribution in the environment through an odor sensor. We found that the odor-tracking performance decreased as the time between the reaction of the odor sensor and the presentation of the pheromone to the silk moth increased. The fact that motor manipulations can be compensated for by enabling a comparison of expected and actual motions, as represented by corollary discharge [63], whereas sensory manipulations cannot, may explain this. Corollary discharge is a means of distinguishing sensory input from own movement from sensory input from the outside world. Previous research focusing on crickets has revealed corollary discharge at the neural circuit level [64]. All animals need a means by which to distinguish sensory inputs caused by their own movements from sensory inputs that are due to sources in the outside world. After detecting an odor, the silk moth shortens its distance from the odor source by moving in a straight line. Hence, this straight-line behavior is an important element of efficiency; however, its behavioral threshold is not constant and has been reported to fluctuate according to serotonin levels in the brain [65]. Furthermore, it has been suggested that a projection neuron from the antennal lobe, the primary olfactory center where information received at the antennae is first transmitted, may be able to interpret the odor distribution in space by differential quantities and not by the absolute concentration of pheromones [66]. Based on these findings, the 60% localization success rate, even with the manipulation of  
Figure 3: Schematic diagram of the tethered behavior measurement system. sensory input and motor output, suggests that adaptive behavior is emergent through simple reflex behavior and constant modulation of the threshold for behavioral decision making.