Max Planck Institute for Dynamics and Self-Organization -- Department for Nonlinear Dynamics and Network Dynamics Group
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Tuesday, 11.01.2011 17 c.t.

Sensory representations in primary visual cortex: connectivity and network dynamics

by Dr. Tom Mrsic-Flogel
from Department of Neuroscience, Physiology and Pharmacology, University College London, UK

Contact person: Fred Wolf


Seminarraum Haus 2, 4. Stock (Bunsenstr.)


Neuronal connectivity is fundamental to information processing in the brain. Understanding the mechanisms of sensory processing, therefore, requires uncovering how connection patterns between neurons relate to their function. This has not been attempted with existing approaches, because neuronal functionality has to be assessed in the intact brain (electrode recordings, two-photon calcium imaging), while synaptic connectivity mapping is only feasible in brain slices (paired whole-cell recordings). To provide a solution to this problem, we have combined three powerful techniques that enable us first to visualise and characterise response properties of hundreds of neurons in the cortex with two-photon calcium imaging, then to identify the same neurons in slices of the same tissue using custom 3D image registration algorithms, and finally assay synaptic connections between a subset of these neurons with multiple whole-cell recordings. Applying this approach to mouse visual cortex, we found that connection probability was related to the similarity of visually driven neuronal activity. Neurons with the same preference for oriented stimuli connected at twice the rate of neurons with orthogonal orientation preferences. Neurons responding similarly to naturalistic stimuli formed connections at very high rates, while those with uncorrelated responses were rarely connected. Bidirectional synaptic connections were found more frequently between neuronal pairs with strongly correlated visual responses. Our results reveal a high degree of functional specificity of synaptic connections in local cortical circuits, and point to the existence of fine-scale subnetworks dedicated to processing related sensory information.

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