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SUMMARY:Robust signal amplification and information integration via self-t
 uned proximity to bifurcation points - Isabella Graf (EMBL Heidelberg)
DTSTART:20250520T120000Z
DTEND:20250520T130000Z
UID:TALK231256@talks.cam.ac.uk
CONTACT:Sarah Loos
DESCRIPTION:In various biological systems information from many noisy mole
 cular receptors must be integrated into a collective response. A striking 
 example is the thermal imaging organ of pit vipers. Single nerve fibers in
  the organ reliably respond to mK temperature increases\, a thousand times
  more sensitive than their molecular sensors\, thermo-TRP ion channels. We
  propose a mechanism for the integration of this molecular channel informa
 tion. Amplification of the signal arises due to proximity to a dynamical b
 ifurcation\, separating a regime with frequent and regular firing of actio
 n potentials (APs)\, from a regime where AP firing is irregular and infreq
 uent. Near the transition\, AP frequency can have an extremely sharp depen
 dence on temperature\, naturally accounting for the thousand-fold amplific
 ation. Furthermore\, close to the bifurcation\, most of the information ab
 out temperature available in the TRP channels’ kinetics can be read out 
 from the times between consecutive APs even in the presence of extrinsic n
 oise. A key model prediction is that the coefficient of variation in the d
 istribution of interspike times decreases with AP frequency\, and quantita
 tive comparison with experiments suggests that nerve fibers of snakes are 
 indeed located very close to the bifurcation. While proximity to such bifu
 rcation points typically requires fine-tuning of parameters\, having feedb
 ack act from the order parameter (AP frequency) onto the control parameter
  robustly maintains the system in the vicinity of the bifurcation. This ro
 bustness suggests that similar feedback mechanisms might be found in other
  sensory systems which also need to detect tiny signals in a varying envir
 onment. To illustrate this idea\, I’ll also briefly mention other sensor
 y systems for which we hypothesize a similar amplification mechanism due t
 o self-tuned proximity to a critical point with diverging susceptibility.
LOCATION:Center for Mathematical Sciences\, Lecture room MR4
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