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Singh SH, van Breugel F, Rao RPN, Brunton BW. Emergent behaviour and neural dynamics in artificial agents tracking odour plumes. NAT MACH INTELL 2023; 5:58-70. [PMID: 37886259 PMCID: PMC10601839 DOI: 10.1038/s42256-022-00599-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 12/01/2022] [Indexed: 01/26/2023]
Abstract
Tracking an odour plume to locate its source under variable wind and plume statistics is a complex task. Flying insects routinely accomplish such tracking, often over long distances, in pursuit of food or mates. Several aspects of this remarkable behaviour and its underlying neural circuitry have been studied experimentally. Here we take a complementary in silico approach to develop an integrated understanding of their behaviour and neural computations. Specifically, we train artificial recurrent neural network agents using deep reinforcement learning to locate the source of simulated odour plumes that mimic features of plumes in a turbulent flow. Interestingly, the agents' emergent behaviours resemble those of flying insects, and the recurrent neural networks learn to compute task-relevant variables with distinct dynamic structures in population activity. Our analyses put forward a testable behavioural hypothesis for tracking plumes in changing wind direction, and we provide key intuitions for memory requirements and neural dynamics in odour plume tracking.
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Yamada M, Ohashi H, Hosoda K, Kurabayashi D, Shigaki S. Multisensory-motor integration in olfactory navigation of silkmoth, Bombyx mori, using virtual reality system. eLife 2021; 10:72001. [PMID: 34822323 PMCID: PMC8629422 DOI: 10.7554/elife.72001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 11/10/2021] [Indexed: 12/04/2022] Open
Abstract
Most animals survive and thrive due to navigational behavior to reach their destinations. In order to navigate, it is important for animals to integrate information obtained from multisensory inputs and use that information to modulate their behavior. In this study, by using a virtual reality (VR) system for an insect, we investigated how the adult silkmoth integrates visual and wind direction information during female search behavior (olfactory behavior). According to the behavioral experiments using a VR system, the silkmoth had the highest navigational success rate when odor, vision, and wind information were correctly provided. However, the success rate of the search was reduced if the wind direction information provided was different from the direction actually detected. This indicates that it is important to acquire not only odor information but also wind direction information correctly. When the wind is received from the same direction as the odor, the silkmoth takes positive behavior; if the odor is detected but the wind direction is not in the same direction as the odor, the silkmoth behaves more carefully. This corresponds to a modulation of behavior according to the degree of complexity (turbulence) of the environment. We mathematically modeled the modulation of behavior using multisensory information and evaluated it using simulations. The mathematical model not only succeeded in reproducing the actual silkmoth search behavior but also improved the search success relative to the conventional odor-source search algorithm.
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Affiliation(s)
- Mayu Yamada
- Graduate School of Engineering Science, Osaka University, Osaka, Japan
| | - Hirono Ohashi
- Graduate School of Engineering Science, Osaka University, Osaka, Japan
| | - Koh Hosoda
- Graduate School of Engineering Science, Osaka University, Osaka, Japan
| | - Daisuke Kurabayashi
- Department of Systems and Control Engineering, Tokyo Institute of Technology, Tokyo, Japan
| | - Shunsuke Shigaki
- Graduate School of Engineering Science, Osaka University, Osaka, Japan
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Wang X, Guo S, Li Z, Luo Q, Dai Y, Zhang H, Ye Y, Gong Q, Luo K. Amphiphilic branched polymer-nitroxides conjugate as a nanoscale agent for potential magnetic resonance imaging of multiple objects in vivo. J Nanobiotechnology 2021; 19:205. [PMID: 34243760 PMCID: PMC8272293 DOI: 10.1186/s12951-021-00951-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 07/01/2021] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND In order to address the potential toxicity of metal-based magnetic resonance imaging (MRI) contrast agents (CAs), a concept of non-metallic MRI CAs has emerged. Currently, paramagnetic nitroxides (such as (2,2,5,5-tetramethylpyrrolidine-1-oxyl, PROXYL), (2,2,6,6-tetramethylpiperidine-1-oxide, TEMPO), etc.) are being extensively studied because their good stability and imaging mechanism are similar to metal-based contrast agents (such as Gd3+ chelate-based clinical CAs). However, a lower relaxivity and rapid in vivo metabolism of nitroxides remain to be addressed. Previous studies have demonstrated that the construction of macromolecular nitroxides contrast agents (mORCAs) is a promising solution through macromolecularization of nitroxides (i.e., use of large molecules to carry nitroxides). Macromolecular effects not only increase the stability of nitroxides by limiting their exposure to reductive substances in the body, but also improve the overall 1H water relaxation by increasing the concentration of nitroxides and slowing the molecular rotation speed. RESULTS Branched pDHPMA-mPEG-Ppa-PROXYL with a high molecular weight (MW = 160 kDa) and a nitroxides content (0.059 mmol/g) can form a nanoscale (~ 28 nm) self-assembled aggregate in a water environment and hydrophobic PROXYL can be protected by a hydrophilic outer layer to obtain strong reduction resistance in vivo. Compared with a small molecular CA (3-Carboxy-PROXYL (3-CP)), Branched pDHPMA-mPEG-Ppa-PROXYL displays three prominent features: (1) its longitudinal relaxivity (0.50 mM- 1 s- 1) is about three times that of 3-CP (0.17 mM- 1 s- 1); (2) the blood retention time of nitroxides is significantly increased from a few minutes of 3-CP to 6 h; (3) it provides long-term and significant enhancement in MR imaging of the tumor, liver, kidney and cardiovascular system (heart and aortaventralis), and this is the first report on nitroxides-based MRI CAs for imaging the cardiovascular system. CONCLUSIONS As a safe and efficient candidate metal-free magnetic resonance contrast agent, Branched pDHPMA-mPEG-Ppa-PROXYL is expected to be used not only in imaging the tumor, liver and kidney, but also the cardiovascular system, which expands the application scope of these CAs.
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Affiliation(s)
- Xiaoming Wang
- Huaxi MR Research Center (HMRRC), Department of Radiology, National Clinical Research Center for Geriatrics, Frontiers Science Center for Disease-Related Molecular Network, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, 610041, Chengdu, China
- Department of Radiology, Chongqing General Hospital, University of Chinese Academy of Sciences (UCAS), No. 104 Pipashan Main Street, Yuzhong District, 400014, Chongqing, China
| | - Shiwei Guo
- Department of Pharmacy of the Affiliated Hospital of Southwest Medical University, Southwest Medical University, Sichuan Province, 646000, Luzhou, People's Republic of China
- Nuclear Medicine and Molecular Imaging Key Laboratory of Sichuan Province, 646000, Luzhou, People's Republic of China
| | - Zhiqian Li
- Huaxi MR Research Center (HMRRC), Department of Radiology, National Clinical Research Center for Geriatrics, Frontiers Science Center for Disease-Related Molecular Network, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, 610041, Chengdu, China
| | - Qiang Luo
- Huaxi MR Research Center (HMRRC), Department of Radiology, National Clinical Research Center for Geriatrics, Frontiers Science Center for Disease-Related Molecular Network, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, 610041, Chengdu, China
| | - Yan Dai
- Department of Pharmacy of the Affiliated Hospital of Southwest Medical University, Southwest Medical University, Sichuan Province, 646000, Luzhou, People's Republic of China
- Nuclear Medicine and Molecular Imaging Key Laboratory of Sichuan Province, 646000, Luzhou, People's Republic of China
| | - Hu Zhang
- Amgen Bioprocessing Centre, Keck Graduate Institute Claremont, 91711, Claremont, CA, USA
| | - Yun Ye
- Department of Pharmacy of the Affiliated Hospital of Southwest Medical University, Southwest Medical University, Sichuan Province, 646000, Luzhou, People's Republic of China
| | - Qiyong Gong
- Huaxi MR Research Center (HMRRC), Department of Radiology, National Clinical Research Center for Geriatrics, Frontiers Science Center for Disease-Related Molecular Network, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, 610041, Chengdu, China
- Functional and Molecular Imaging Key Laboratory of Sichuan Province, Research Unit of Psychoradiology, Chinese Academy of Medical Sciences, 610041, Chengdu, China
| | - Kui Luo
- Huaxi MR Research Center (HMRRC), Department of Radiology, National Clinical Research Center for Geriatrics, Frontiers Science Center for Disease-Related Molecular Network, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, 610041, Chengdu, China.
- Functional and Molecular Imaging Key Laboratory of Sichuan Province, Research Unit of Psychoradiology, Chinese Academy of Medical Sciences, 610041, Chengdu, China.
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