Dynamics in Networks of Cultured Neurons

Cultured networks of neurons from hippocampus constitute a fascinating reductionist model for biological computation. While individual neurons retain the physiological characteristics as in the intact brain, the structure and connectivity in the network are considerably simpler to measure and analyze, and therefore to engineer and design. We show that disconnected single neurons oscillate independently of each other, and that when the network is connected they synchronize into periodic network bursts in which all neurons fire together. This behavior is attributed to Kuramoto-Strogatz like behavior for the synchronization of pulse-coupled oscillators. We investigate how initiation of this burst is brought about, and find that the recruitment of a minimal cohort of firing units plays a crucial role in the process. Activation of the whole network is well described by a theoretical model of percolation invoking the need for ‘quorum’ decision making.