| NSF Org: |
IOS Division Of Integrative Organismal Systems |
| Recipient: |
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| Initial Amendment Date: | June 24, 2016 |
| Latest Amendment Date: | June 24, 2016 |
| Award Number: | 1557610 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Patrick Abbot
dabbot@nsf.gov (703)292-0000 IOS Division Of Integrative Organismal Systems BIO Directorate for Biological Sciences |
| Start Date: | July 1, 2016 |
| End Date: | March 31, 2020 (Estimated) |
| Total Intended Award Amount: | $339,998.00 |
| Total Awarded Amount to Date: | $339,998.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
323 DR MARTIN LUTHER KING JR BLVD NEWARK NJ US 07102-1824 (973)596-5275 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
323 DOCTOR MARTIN LUTHER KING NEWARK NJ US 07102-1982 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | Animal Behavior |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.074 |
ABSTRACT
Most of life is brainless and the vast majority of organisms on Earth lack neurons altogether. These organisms include plants, fungi, and bacteria (both non-pathogenic and disease-causing types), who all must cope with the same problem as humans - make the best choices in an ever changing world or risk dying - but without the help of a brain or even a simple nervous system. This project will explore the decision-making abilities of one of these neuron-less organisms, the slime mold Physarum polycephalum. Of particular interest is (1) how P. polycephalum integrates noisy and sometimes contradictory information when selecting a food source; and (2) the role of its past experiences (e.g. the resources it has previously visited) on the outcome of its future choices. Because P. polycephalum is a macroscopic unicellular organism, it can be easily manipulated and observed, while retaining similar characteristics to other neuron-less, microscopic creatures. It is therefore a perfect model system to understand how most living beings integrate complex and dynamical information. The project will train 2 graduate students and at least 15 undergraduate and high school students in integrative research at one of the most diverse campuses in the US (Rutgers-Newark and NJIT, both located in Newark, NJ) and at a collaborating lab in Sydney, Australia. "Hands-on", open sourced demonstration kits for K-12 classes to experiment with slime mold locomotion and decision-making will be developed to encourage the study of cognitive processes in neuron-less organisms and other non-traditional model organisms.
The proposed project will set up a comprehensive experimental and theoretical framework that can be used beyond the scope of this project to study decision-making in other neuron-less organisms and to establish comparisons with brained animals, thereby advancing our comprehension of the emergence of cognitive processes in biological systems. Cell micromanipulation and calcium imaging combined with analytical tools from neurophysiology and statistical physics will be used to first investigate the role of contractile oscillations of P. polycephalum's cellular plasma membrane in its decision-making process. In particular, the transfer and integration of information from different stimuli will be examined. The efficiency of the slime mold decision-making mechanism when the available information is noisy or contradictory will also be tested. Finally, whether the slime mold's natural positive geotaxis (motion in the direction of gravity) can be conditioned (i.e., reversed here) if food is always present uphill will be determined. This would indicate that the slime mold is capable of spatial associative learning (a first in the slime mold), and that its decision-making process is capable of adapting to the characteristics of the environment through which it moves. All methods, results and software developed during this project will be made freely available on a repository hosted by the Open Science Framework.
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
Most of life is brainless and the vast majority of organisms on Earth lack neurons altogether. These organisms include plants, fungi, and bacteria (both non-pathogenic and disease-causing types), who all must cope with the same problem as humans - make the best choices in an ever changing world or risk dying - but without the help of a brain or even a simple nervous system. This project explored the decision-making abilities of one of these neuron-less organisms, the slime mold Physarum polycephalum. P. polycephalum is a macroscopic unicellular organism capable of solving complex problems, such as finding the shortest path in a maze, selecting the best of multiple options, and forming robust and efficient transportation networks. Recently, researchers have even demonstrated that P. polycephalum was capable of habituation, a basic form of memory. Because it can be easily observed and manipulated, it is, therefore, a perfect model system to understand how non-neuronal organisms integrate complex and dynamical information.
In this project, we studied two specific questions: (1) how does P. polycephalum integrates noisy and sometimes contradictory information when selecting a food source? And (2), what is the role of its past experiences (e.g. the resources it has previously visited) on the outcome of its future choices? For (1), we showed that the decision-making behavior of P. polycephalum is not driven by the part of its body in contact with a positive stimuli but by the parts that are away from it. This counterintuitive result can be explained by the fact that the contractile activity and rigidity of the cell membrane decreases where it is in contact with food while remaining higher everywhere else. This effectively creates a pressure differential that generate a net flow of cytoplasm (the solution that contains all of the material within the cell) from the rest of the cell towards the part that touches the food. This result illustrates how simple physical properties can be exploited to solve problems, suggesting that primitive cognition does not require neurons and can be achieved using biophysical processes instead.
For (2), we showed that the exploration behavior of P. polycephalum changes as a function of the spatial distribution of food sources it has previously been exposed to and as a function of its nutritional state (fed vs starved). In particular, P. polycephalum appears to be building smaller, denser exploration networks when fed and when it was previously exposed to a dense distribution of food sources than when it is starved or was exposed to sparsely distributed food sources. These results confirm that unicellular organisms behave differently depending on their life history and that, therefore, there exists a form of cellular memory. Understanding the molecular basis of that memory would allow for answering fundamental questions on the evolution of cognition and behavior, and for advances in regenerative medicine.
The experimental work performed during this project led to the creation of a mathematical model. This model will be instrumental in generating future testable predictions regarding the integration of multiple sources of information and contradicting stimuli during the decision making process of P. polycephalum. It will also allow us to explore more complex decision making scenarios that may not be experimentally tractable. Moreover, this model may lead to advances in machine learning and artificial intelligence by proposing a new paradigm for decision making that is not based on the traditional neurocentric model that is the bedrock of artificial neural networks.
Finally, this project provided hands-on training in research methodology, lab techniques, data acquisition and processing, and/or mathematical modeling to 2 graduate students, 11 undergraduate students, and 5 high school students (9 female students and 9 male students overall). It also led to the creation of "Peek@bug", an affordable automated tabletop behavioral observation chamber targeted at schools and young (and less young) science enthusiasts, which specifications and code will be made publicly available. The project also generated high-profile coverage in the press, with several mentions in popular science outlets such as The Verge, Science Friday, and Quanta Magazine, and its results were presented at several high-profile popular science events such as Pioneer Works' pop-up events, Secret Science Club, and the World Science Festival.
Last Modified: 12/14/2020
Modified by: Simon Garnier
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