Research Highlight: Spontaneous Neuronal Network Dynamics Reveal Circuit’s Functional Adaptations for Behavior

The neuronal and the biological rôle of the brain spontaneous activity is still elusive. . Here, using two-photon calcium imaging at the single-neuron level of intact zebrafish larvae to monitor the spontaneous activity in a sensory brain area (the optic tectum), ENP team leader Germán Sumbre and colleagues demonstrate that spontaneous activity is organized according to neuronal assemblies with attractor-like dynamics  and reflect the tectal retinotopic map. The neuronal assemblies showed attractor-like dynamics advantegeous  for visual detection in noisy natural environments, enabling efficient extraction of behaviorally relevant and vital sensory information. Finally, the neuronal assemblies' properties matched those measured during prey detection, and their spontaneous activation predicted spontaneous directional tail movements. 

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Spontaneous Neuronal Network Dynamics Reveal Circuit’s Functional Adaptations for Behavior, Sebastián A. Romano, Thomas Pietri, Verónica Pérez-Schuster, Adrien Jouary, Mathieu Haudrechy, Germán Sumbre. Neuron (2015) Mar 4;85(5):1070-85. doi: 10.1016/j.neuron.2015.01.027. Epub 2015 Feb 19. 

This is an open access article under the CC BY-NC-ND license (

 Fig legend

(A) Spontaneously emerging retinotopic-like map in one typical experiment. Spont., all the spontaneous assemblies whose centroids lay on the right (R.) and left (L.) tecti. Neurons belonging to assemblies with similar topographic centroids were similarly colored. The colors represent the average normalized rostro-caudal centroid position of their assemblies. The transparency represents the SD across centroids. Stim. L. and R.: the same representation for the light-spot-induced responses. Note the resemblance between Spont. and Stim. panels, showing a graded change in colors along the rostro-caudal axes.

 (B) Top: topography examples of spontaneous assemblies with step-like non-linear dynamics (assembly neurons in yellow). Bottom: corresponding raw data (dots) and regression fits (black curves) of the activation probabilities of the assembly’s neurons. Note the all-or-none-like nature of these curves, suggesting highly recurrent facilitatory cooperative dynamics.