Biology subjects

Kazawa, T.

Publications and source records attributed to Kazawa, T..

3 recordsLinked to original sources

bioRxiv2024

Adaptive decision-making by ants in response to past, imminent, and predicted adversity

Many animals exhibit innate behaviours, which are often interpreted as hard-wired, reflex-like responses, particularly in insects. Among these behaviours, beacon-aiming--an approach towards dark areas or objects--is observed in many animals; however, its functional significance remains unclear, and some ant species do not exhibit it. Here we show that in one such species, Camponotus japonicus, the behaviour was triggered only under adverse substrate conditions, such as during the crossing of liquid-covered surfaces, regardless of the locomotor patterns like walking or swimming, or the mere presence of water, or when walking upside-down. Once initiated, beacon-aiming persists even under normal substrate conditions, as demonstrated by ants transitioning from water-covered to dry substrates suitable for comfortable walking. This behavioural flexibility indicates that the innate behaviour is not hard-wired but modulated by internal states. Furthermore, changes in internal states may serve adaptive decision-making, potentially allowing ants to prepare for future adverse conditions. The isolated ants on a water-surrounded platform gradually established an attraction to the direction of the beacon before ultimately swimming towards it. These findings suggest that beacon-aiming is regulated by internal states, especially anxiety-like states formed in response to past, imminent, and predicted adverse substrate conditions in ants.

animal behavior and cognition↗

bioRxiv2022

High performance, large-scale multi-compartment Hodgkin-Huxley simulation of Drosophila's whole-brain neural circuit model

A major challenge in neurosciences is the elucidation of neural mechanisms in brains that are crucial for the processing of sensory information and the generation of adaptive behavior. In conjunction with the ever-growing body of experimental data, computational simulations have become crucial in integrating information and testing hypotheses, requiring fast large-scale simulators. We constructed a whole-brain neural circuit model of the fly Drosophila with biophysically detailed multi-compartment Hodgkin-Huxley models based on the morphologies of individual neurons published in open databases. Performance tuning of the simulator enabled near real-time simulation of the resting state of the Drosophila whole-brain model in the large-scale computational environment of the supercomputer Fugaku, for which we achieved in excess of 630 TFLOPS using 480k cores. In our whole-brain model, neural circuit dynamics related to a standard insect learning paradigm, the association of taste rewards with odors could be simulated.

neuroscience↗

bioRxiv2021

Ambiguous Body Ownership Experience Caused by Feeling-judgement Conflict: Evidence from Subjective Measurement in Rubber Hand Illusion using Integrated Information Theory

AO_SCPLOWBSTRACTC_SCPLOWHuman body awareness is malleable and adaptive to changing contexts. The illusory sense of body-ownership has been studied since the publication of the rubber hand illusion, where ambiguous body ownership feeling, expressed as "the dummy hand is my hand even though that is not true", was first defined. Phenomenologically, the ambiguous body ownership is attributed to a conflict between feeling and judgement; in other words, it characterises a discrepancy between first-person (i.e. bottom-up) and third-person (i.e. top-down) processes. Although Bayesian inference can explain this malleability of body image sufficiently, the theory does not provide a good illustration of why we have different experiences to the same stimuli - the difficulty lies in the uncertainty regarding the concept of judgement in their theory. This study attempts to explain subjective experience during rubber hand illusions using integrated information theory (IIT). The integrated information {Phi} in IIT measures the difference between the entire system and its subsystems. This concept agrees with the phenomenological interpretation - that is, there is conflict between judgement and feeling. By analysing the seven nodes of a small body- brain system, we demonstrate that the integrity of the entire system during the illusion decreases with increasing integrity of its subsystems. These general tendencies agree well with many brain-image analyses and subjective reports; furthermore, we found that subjective ratings were associated with the {Phi}s. Our result suggests that IIT can explain the general tendency of the sense of ownership illusions and individual differences in subjective experience during the illusions.

animal behavior and cognition↗