Biology subjects

Nakazono, T.

Publications and source records attributed to Nakazono, T..

3 recordsLinked to original sources

bioRxiv2025

Deletion of the 5-HT3A receptor reduces behavioral persistence and enhances flexibility

The 5-HT3A receptor is the only ionotropic serotonin receptor and has been implicated in cognitive functions, yet its specific role remains unclear. To investigate the contribution of the 5-HT3A subtype, we trained wild-type (C57BL/6J) and 5-HT3A receptor knockout (Htr3a-/-) mice across a series of operant conditioning tasks and compared their behavioral performance. Following nose-poke training, both groups underwent a rule-switching task, extinction tests under fixed ratio (FR) and variable ratio (VR) reinforcement schedules, and a progressive ratio (PR) task to assess persistence. We found that 5-HT3A receptor knockout mice exhibited reduced responding during the extinction and PR tasks, suggesting diminished behavioral persistence. Notably, however, knockout mice acquired the new rule in the switching task significantly faster than wild-type controls, indicating enhanced cognitive flexibility. These findings suggest that the 5-HT3A receptor plays a role in regulating the balance between behavioral persistence and flexibility, normally biasing this balance toward persistence under normal physiological conditions. This mechanism may underlie the therapeutic effect of 5-HT3A receptor antagonists in treatment-resistant obsessive-compulsive disorder (OCD). HighlightsO_LICognitive abilities of 5-HT3A receptor-deficient (Htr3a-/-) mice were examined using an operant conditioning paradigm. C_LIO_LI5-HT3A receptor knockout mice exhibited reduced responding during extinction and progressive ratio (PR) tasks, indicating diminished behavioral persistence. C_LIO_LI5-HT3A receptor knockout mice showed more rapid acquisition in a rule-switching task compared to wild-type mice, suggesting enhanced flexibility. C_LIO_LIThe 5-HT3A receptor contributes to the balance between behavioral persistence and flexibility. C_LIO_LIThis function may underlie the therapeutic effects of 5-HT3A receptor antagonists in treatment-resistant obsessive-compulsive disorder (OCD). C_LI

neuroscience↗

bioRxiv2025

Observation of tandem running behavior in mating pairs of Asian dampwood termite, Hodotermopsis sjostedti

As a social insect, termite colonies can grow to a group of millions of individuals, yet all colonies start from a single mating pair. Recent studies indicate that the pair formation process shows a large diversity among species, especially in basal lineages. Thus, comparative information is integral to estimating the ancestral state of this essential stage of the termite life cycle. The Asian dampwood termite, Hodotermopsis sjostedti, has been well-studied as a model basal termite of caste differentiation processes. Yet, their pair formation remains undocumented. In this study, we found that mating pairs of H. sjostedti show clear tandem running behavior. Both females and males played a leading role, with females showing more leader roles, and they switched their leading roles even within the same pair. We also found that dish size affected tandem movement coordination; pairs showed faster and more stable tandem running in a larger dish. We provide a tracking dataset of 17 body parts, including antennal and leg movements during tandem runs, which can be utilized in future comparative studies. This study supports the idea that tandem running existed in the early ancestors of termites and sheds light on the origin of termite mate pairing.

animal behavior and cognition↗

bioRxiv2024

Fight, Retreat, Repeat: Field observation of male-male agonistic behavior in the wood-feeding cockroach, Panesthia angustipennis spadica (Dictyoptera: Blattodea: Blaberidae)

Conflict is one of the most critical factors affecting the behavior of animals related to their reproduction and survival, with aggressive interactions being central to acquiring resources or mating partners. This phenomenon is more common among males than females, impacting reproduction strategy and beginning of biparental care. Investigating such interactions in species closely related to social species can be illuminating, offering valuable insights into the factors that influence the emergence and maintenance of more complex social behaviors. In this context, we present a field study of male-male agonistic behavior in the wood-feeding cockroach, Panesthia angustipennis. Panesthia is the closest genus to the subsocial genus Salganea, which is known for its biparental care. Our field observations reveal a characteristic behavior where one male pushes a rival away from a female. The victorious male repeatedly returns to a specific site near the female, suggesting a strategy to minimize unnecessary conflict or protect the female. This behavior provides insights into the potential evolutionary strategies that may have evolved in the common ancestor shared by Salganea and Panesthia. Notably, the displaced males persistently reengage, highlighting the high resource value attributed to females and the consequential intensity of male competition. This study not only sheds light on the aggressive and pacifist tendencies in P. angustipennis but also contributes to understanding the evolutionary development of social structures in Salganea. Further experimental investigations into the aggressive behaviors of P. angustipennis will enhance our comprehension of the factors shaping the evolution of sociality in these species.

animal behavior and cognition↗