Spontaneous neuronal network dynamics reveals circuit's functional adaptations for behavior

SEBASTIÁN A. ROMANO

Mar del Plata

Congreso; XXX Congreso Anual de la Sociedad Argentina de Investigación en Neurociencias; 2015

The brain spontaneously produces activity patterns, even in the absence ofsensory stimulation. This ongoing activity was once considered as neuronalnoise with no functional value. However, spontaneous activity dynamicallyengages in network states that mimic patterns of sensory-induced activities,potentially playing a role in brain computations. Nevertheless, the neuronalinteractions underlying these spontaneous activity patterns, and their truebiological relevance, remain elusive. I will present a recent work1 that shedslight over these issues. Using 2-photon calcium imaging of intact GCaMPexpressingtransgenic zebrafish larvae, I monitored the spontaneous activity inthe optic tectum. In zebrafish, the tectum is the most complex visual region,containing a retinotopic visual map that is essential for visually guided preydetection and capture. Spontaneous tectal activity was organized in neuronalclusters, representing visual assemblies that specifically grouped functionallysimilar neurons. Collectively, they reflected the tectal retinotopic map, even inthe absence of retinal inputs. These assemblies consisted of all-or-none-likecooperative sub-networks shaped by competitive dynamics, a mechanismsuited for their efficient recruitment. Notably, the spontaneous visualassemblies were tuned to the same angular sizes and spatial positions as larva'sprey-detection performance in behavioral assays, and their spontaneousactivation predicted directional tail movements. These results reveal thatstructured spontaneous activity represents ?preferred? network states tuned tobehaviorally relevant features, emerging from the functionally adapted intrinsicnon-linear dynamics of neuronal circuits.