News Release

An AI technology to reveal the characteristics of animal behavior only from the trajectory

STEFTR: A hybrid versatile method for state estimation and feature extraction from the trajectory of

Peer-Reviewed Publication

Osaka University

AI Analysis

image: This is AI analysis of movement. Conceptual drawing of 'AI analysis of movement'. view more 

Credit: © Kotaro Kimura

Recording the movements of people and animals (including birds and insects) has become very easy because of the development of small and inexpensive GPS devices and video cameras. However, it is still difficult to infer what triggers such movements (for example, external stimuli and/or their mental processes) from the behavioral records.

In this study, Shuhei Yamazaki and colleagues have developed an artificial intelligence (AI) technology, first, to estimate an animal's behavioral state, such as "resting", "feeding", or "traveling", without human classification, and, next, to explore the characteristics of each behavioral state by comparing responses under different conditions, such as before and after experiencing a certain stimulus.

This method, termed STEFTR (state estimation and feature extraction of animal behavior), enabled the researchers to estimate the behavioral states of roundworms and penguins that move approximately 1 cm in 10 min in a petri dish and several kilometers in 1 day or more in the Antarctic Ocean, respectively, by analyzing them in exactly the same way. Notably, they achieved > 90% accuracy using only tens of animal trajectories, although traditionally researchers used prior knowledge of specialists about the animal's movement and/or millions of video images of animal behavior to train AI.

In the feature extraction, Yamazaki et al. revealed experience-dependent (i.e., "learning"-dependent) changes in specific behavioral aspects in worms and bats, and sexual pheromone-dependent changes in fruit flies. Moreover, they revealed changes in nerve activity that is linked to behavioral change in worms.

In conclusion, the STEFTR method may make it easy to infer "important places" for animal behavior, such as nests and feeding places that are usually difficult to find, using only trajectory data of wild animals. In addition, it may help discover important brain activities related to animal behavior, thereby contributing to the progress of basic brain science.


The article "STEFTR: A hybrid versatile method for state estimation and feature extraction from the trajectory of animal behavior" was published in the journal of Frontiers in Neuroscience at

About Osaka University

Osaka University was founded in 1931 as one of the seven imperial universities of Japan and now has expanded to one of Japan's leading comprehensive universities. The University has now embarked on open research revolution from a position as Japan's most innovative university and among the most innovative institutions in the world according to Reuters 2015 Top 100 Innovative Universities and the Nature Index Innovation 2017. The university's ability to innovate from the stage of fundamental research through the creation of useful technology with economic impact stems from its broad disciplinary spectrum.


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