Webcast of Mike Paulin's seminar on 'The Origin of Inference'

Mike Paulin (Department of Zoology, University of Otago, New Zealand) visited Northwestern University to deliver a seminar entitled 'The origin of inference: Ediacaran ecology and the evolution of spiking neurons.'  This symposium was the first to be cosponsored by the Department of Neurobiology (Wienberg College of Arts and Sciences) and the Neuroscience and Robotics Lab (McCormick School of Engineering).  

The webcast of the seminar can be found here.

Abstract: Suspension feeding and grazing animals with no nervous systems existed during the Ediacaran period, from c635Ma to the onset of the Cambrian explosion c543Ma.  The two surviving Ediacaran phyla, poriferans and placozoans, have no neurons but can sense, recognize and move in relation to external threats and opportunities.  Spikes are expensive – they each cost about 106 ATP molecules – so why buy a spiking neuron when you’ve been getting along just fine without them for 90 million years?  Fossil evidence indicates spiking neurons evolved when animals started eating each other, about 550Ma.  Unlike their predecessors who swept nutrients continuously from the environment, carnivores play an episodic game, in which timing is everything and the stakes are very high.  I will show that a spiking neuron is a Bayes-optimal decider for triggering strike/escape behaviour, given a noisy signal from an approaching opportunity/threat.  A population of such neurons can infer and represent the Bayesian posterior density of a parameter of the signal source (e.g. its location) in real time.  This may provide a foundation for explaining why, and how, animals with nervous systems today behave as if we are capable of real-time Bayesian causal inference.

Date: 
Friday, May 16, 2014