Our theoretical and computational effort is motivated and inspired by biology. We use physics and machine learning to understand how organisms interact with their environment to support a variety of behaviors. We work closely with a number of longstanding collaborators to design (and also sometimes perform!) experiments which nurture and are nurtured by theory. Here are the creatures and behaviors we currently observe and model with ongoing collaborators:
(1) Fungal growth, spore discharge and dispersal, with A Pringle, Univ Wisconsin Madison; V Norros, Helsinki; A Mazzino, University of Genoa; C Raufaste, F Celestini, R Arkowitz, University of Nice.
(2) Olfactory navigation in mice with D Gire University of Washington.
(3) Olfactory navigation in octopus with D Gire University of Washington and N Bellono Harvard University.
(4) Sensory biology in the sea robin with N Bellono Harvard University.
(5) Collective behavior in the piranhas with N Bellono, Harvard University.
(6) Bacterial biofilms with P Thomen and C Claudet, Université de Nice.
Fungal spore discharge and dispersal
Fungi are the worst threats to animals and plants but also a crucial component of many ecosystems. They lack legs and wings for locomotion, but they are able to translocate even across oceans by dispersing a myriad of microscopic spores in the atmosphere. We started our journey in fungal biology by showing that the physics of spore forcible discharge is highly optimized in a variety of ways. But spore dispersal ultimately is dictated by stochastic transport in the atmosphere. How does microscopic optimization reconcile with large scale uncertainty? Collaboration with: Anne Pringle, University of Wisconsin Madison; Michael Brenner, Harvard University; Marcus Roper, UCLA; Veera Norros, Helsinki.
Anne Pringle - University of Wisconsin Madison
Andrea Mazzino - UNIGE
Annalisa Barla - UNIGE
Veera Norros - Finnish Environmental Institute
[Christophe Raufaste, Franck Celestini, Mederic Argentina, Robert Arkowitz] University Cote d’Azur
Mice Olfactory navigation
The sense of smell is essential to locate food and mates and avoid predators. Technology to record neural activity in mice is extremely well developed. But despite an ever increasing wealth of data, what are the computational principles that allow mice to sense realistic odor plumes and navigate to reach a target remains unknown. We first demonstrated that mice are able to use airborne odor plumes to locate their source, and that within typical experimental arenas, simple algorithms are sufficient for navigation. By exposing awake animals to realistic odor plumes, we demonstrated that the neural activity depends not only on odor intensity but also on its sparsity, suggesting mice may be adapted to turbulence.
Olfactory navigation in octopus
The neural architecture that processes odor is widely conserved in the animal kingdom. Octopuses are a facinating exception, organised in entirely different ways. Their brain is distributed across the arms, with only a small fraction contained in the central brain. They sense odors and mechanical signals with sensors located within the suckers, distributed along their body. Their brain only has an approximate perception about the arms' position in space. How are local vs central decisions negociated? (How) is information shared?
Sensory biology of sea robins
Sea robins are voracious fishes that evolved specialized sensory legs, used to dig prey hidden in sand. We are exploring the sensory biology of this animal and how it is connected to the computational principles that underlie behavior. What specific features of the sensory legs are needed to support behavior? Do all sensory legs comply with these requirements? (How) are computations shaped by the fluid niche where sea robins live?
Our collaborators have just started to run experiments on piranhas as well! This is a brand new project, and we are now thinking about collective prey hunting. We look forward to meet the newly arrived creatures soon.
Nicholas Bellono - Harvard University
Bacteria have long been studied in isolation, but it is now clear since few decades that they mostly live in colonies that resemble multicellular organisms in many ways. We have shown with experiments and theory that this multicellular organisation can lead bacterial biofilms to osmotic expansion on surfaces and that they behave as complex fluids. We are currently investigating experimentally whether collective translocation can emerge from differentiation.
[Philippe Thomen and Cyrille Claudet] University Cote d’Azur