Computing with Assemblies

Computation in the brain has been modeled productively at many scales, ranging from molecules to dendrites, neurons, and synapses, all the way to the whole brain models useful in cognitive science. I will discuss recent work on an intermediate layer, involving assemblies of neurons --- that is to say, sets of neurons firing together in a repetitive pattern whenever we think of a particular memory, concept or idea. Assemblies have been conjectured six decades ago by Hebb, and have been over the past decade noticed in both the animal and the human brain. Further, experiments, simulations, and theoretical analysis suggest that assemblies can be copied from one brain area to another, and associated with other assemblies to encode affinity. We propose a broader "calculus" of assemblies, including operations such as "reciprocal-project" and "merge", comprising a powerful computational model. One interesting hypothesis is that assembly operations may underlie some of the most advanced functions of the brain, such as reasoning, planning, language, math. Work with Santosh Vempala, Wolfgang Maass, and Michael Collins.