SLIDE 1
Continuous attractors as unreliable estimators
Arvind Murugan
- Dept. of Physics
Regression using attractors
Regression Attractor dynamics High dim config space
Continuous attractors as unreliable estimators Arvind Murugan - - PowerPoint PPT Presentation
Continuous attractors as unreliable estimators Arvind Murugan - - PowerPoint PPT Presentation
Continuous attractors as unreliable estimators Arvind Murugan Dept. of Physics Regression using attractors High dim config space Regression Attractor dynamics Circadian clocks as phase estimators External signal (Day-night cycle of light)
SLIDE 2
SLIDE 3
Circadian clocks as phase estimators
Cyanobacteria Synechococcus Elongatus Justin Chew, Rust lab
Gorbunov 2001 External signal (Day-night cycle of light) Time -> Phase estimate (clock state) Time -> clock state clock state Time ->
SLIDE 4
Circadian team
Zhiyue Lu Wee Pittayakanchit Michael Rust Justin Chew Theory Experiment
SLIDE 5
The best estimator?
SLIDE 6
The best estimator?
Internal unreliability
SLIDE 7
Two kinds of bugs Two kinds of estimators
Equally good in noiseless cycling conditions + Internal noise Really bad Bad Good Bad Atmospheric noise Synechococcus Elongatus Procholorococus Marinus Continuous attractor (limit cycle) Point attractor
SLIDE 8
Limit cycle clocks
Synechococcus Elongatus Continuous attractor (limit cycle)
Leypunskiy et al. (eLife 2017) (Rust lab)
SLIDE 9
Point attractor clocks
Synechococcus Elongatus Continuous attractor (limit cycle) Procholorococus Marinus Point attractor
SLIDE 10
Weather fluctuations
External noise
SLIDE 11
Continuous attractors limit dark pulse delays
2.5 hr dark pulse during the day Continuous attractor Point attractor Delay: Delay:
SLIDE 12
Internal noise
Molecules are discrete Particle Diffusion constant Distribution Prochlorococcus Marinus (~ 0.5 um) ~ 400 copies of KaiC Synechococcus Elongatus(~ 3 um) ~ 10000 copies of KaiC Justin Chew, Rust lab ~ 0 copies of KaiC
SLIDE 13
Internal noise
Diffusion (internal noise) No external noise
SLIDE 14
Flatness encourages diffusion Curvature discourages diffusion
Flat Curved
SLIDE 15
External + Internal noise
Gillespie simulation of KaiABC molecular model
Internal noise Fixed External noise
Prochlorococcus Marinus Synechococcus Elongatus
Circadian clocks
SLIDE 16
Different strokes for different folks
SLIDE 17
~ 40000 copies ~ 2500 copies
Experiments by Justin Chew, Rust lab
- S. Elongatus