title: Cultured Cortical Neurons Can Perform Blind Source Separation According to the Free-Energy Principle.
abstract: Blind source separation is the computation underlying the cocktail party effect--a partygoer can distinguish a particular talker's voice from the ambient noise. Early studies indicated that the brain might use blind source separation as a signal processing strategy for sensory perception and numerous mathematical models have been proposed; however, it remains unclear how the neural networks extract particular sources from a complex mixture of inputs. We discovered that neurons in cultures of dissociated rat cortical cells could learn to represent particular sources while filtering out other signals. Specifically, the distinct classes of neurons in the culture learned to respond to the distinct sources after repeating training stimulation. Moreover, the neural network structures changed to reduce free energy, as predicted by the free-energy principle, a candidate unified theory of learning and memory, and by Jaynes' principle of maximum entropy. This implicit learning can only be explained by some form of Hebbian plasticity. These results are the first in vitro (as opposed to in silico) demonstration of neural networks performing blind source separation, and the first formal demonstration of neuronal self-organization under the free energy principle.
authors.affiliation: Department of Human and Engineered Environmental Studies, Graduate School of Frontier Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, Japan.|Research Fellow of Japan Society for the Promotion of Science (JSPS), Kojimachi, Chiyoda-ku, Tokyo, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Isomura
authors.affiliation: Research Center for Advanced Science and Technology, The University of Tokyo, Komaba, Meguro-ku, Tokyo, Japan.|PRESTO, Japan Science and Technology Agency, Honcho, Kawaguchi-shi, Saitama, Japan.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Kotani
authors.affiliation: Department of Precision Engineering, School of Engineering, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Jimbo
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000502:physiology*; D004735:Energy Transfer; D000069550:Machine Learning; D008959:Models, Neurological; D015233:Models, Statistical; D009415:Nerve Net / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D046709:Pattern Recognition, Physiological / Q000502:physiology*; D025341:Principal Component Analysis; D051381:Rats