Colloquium d’Informatique de Sorbonne Université

Christos Papadimitriou, Columbia University

How does the brain make language?

Christos Harilaos Papadimitriou is the Donovan Family Professor of Computer Science at Columbia University. Before joining Columbia in 2017, he was a professor at UC Berkeley for the previous 22 years, and before that he taught at Harvard, MIT, NTU Athens, Stanford, and UCSD. He has written five textbooks and many articles on algorithms and complexity, and their applications to optimization, databases, control, AI, robotics, economics and game theory, the Internet, evolution, and the brain. He holds a PhD from Princeton (1976), and eight honorary doctorates, including from ETH, University of Athens, EPFL, and Univ. de Paris Dauphine. He is a member of the National Academy of Sciences of the US, the American Academy of Arts and Sciences, and the National Academy of Engineering, and he has received the Knuth prize, the Goël prize, the Babbage award, the von Neumann medal, as well as the 2018 Harvey Prize by Technion. In 2015 the president of the Hellenic republic named him commander of the order of the Phoenix. He has also written three novels: "Turing," "Logicomix" and his latest "Independence."

Abstract

There is no doubt that cognition and intelligence are the results of neural activity - but how, exactly? How do molecules, neurons, and synapses give rise to reasoning, language, plans, stories, art, math? Despite dazzling progress in experimental neuroscience, as well as in cognitive science, we do not seem to be making progress on the overarching question. As Richard Axel recently put it in an interview: "We don't have a logic for the transformation of neuronal activity to thought and action. I view discerning [this] logic as the most important future direction of neuroscience". What kind of formal system would qualify as this "logic"? I will introduce a computational system whose basic data structure is the assembly of neurons - assemblies are large populations of neurons known to represent concepts, words, ideas, episodes, etc. The Assembly Calculus is biologically plausible in the sense that Its primitives are behaviors of assemblies observed in, or suggested by, experiments, and can be provably (through both mathematical proof and simulations in biologically realistic platforms) "compiled down" to the activity of neurons and synapses. Using this framework a Parser was constructed which (a) can handle reasonably complex sentences in English and other languages; and (b) works exclusively through the firing of biologically realistic neurons.

The presentation will also be streamed. The link will be available on the Colloquium website [http://www.lip6.fr/colloquium/].