Emergent Behavior of Living Neuronal Networks : Creating circuits and exploring the dynamics of neurons in vitro

In the past two decades there’s been an incredible development in the field of in vitro neural cultures. Thanks to the developments in embryonic stem cell technology, and the ability to produce pluripotent stem cells from adult human cells, producing human neural cultures has become much more widely accessible, and the ability to recreate physiological processes is increasing at an accelerating rate. Neurons in culture, however, do not spontaneously form network structures which resemble those found in the brain, and perhaps as a consequence, exhibit abnormal spontaneous and stimulus-evoked activity. We tested several techniques which aimed at overcoming this challenge, and to create more physiologically relevant cultures. In paper I, we employed a bioprinting approach to achieve controlled deposition of cells on 3D fiber substrates. In paper II, we examined spontaneous self-assembly of clusters of cells on microelectrode arrays as a way of recreating cortical microenvironment. Cluster formation was influenced by cell density and astrocyte concentration, which had a significant effect on spontaneous electrical activity. Lastly, in paper III and IV, we used soft lithography to create perforated microchannels which could guide neuronal connectivity on microelectrode arrays on a network-wide level. Neurons grown in these structures exhibited clustered spontaneous activity and exhibited plasticity when we stimulated them with patterned emulated sensory information. These techniques are all different means to the same end - to create better representations of the human brain in vitro.