A neuronal microcircuit is the smallest functional ecosystem in any brain region that encompasses a diverse morphological and electrical assortment of neurons, and their synaptic interactions. Blue Brain has pioneered data-driven digital reconstructions and simulations of microcircuits to investigate how local neuronal structure gives rise to global network dynamics. These methods could be extended to digitally reconstruct microcircuits in any brain region.

Rat Somatosensory Cortex

Blue Brain’s NMC portal allows researchers to access the experimental data used in the reconstruction process, download cellular and synaptic models, and analyze the predicted properties of the microcircuit: six layers, ~31,000 neurons, 55 morphological types, 11 electrical types, 207 morpho-electrical types, anatomy and physiology of ~40 million intrinsic synapses and 1941 unique synaptic connection types between neurons of specific morphological types.  It also provides data supporting comparison of the anatomy and physiology of the reconstructed microcircuit against results in the literature.

Rat Hippocampus CA1

The model of a dense reconstruction of rat hippocampus CA1 microcircuit was built using a bottom-up data-driven workflow, along the same lines followed to implement a cortical column (Markram et al., 2015). The network is composed of 42 morphologically and biophysically accurate neurons (24 excitatory and 18 inhibitory) divided into 13 morphological types and 17 morpho-electrical types, 156 potential pathways, and 7 intrinsic synapse types. The microcircuit is part of the Blue Brain collaboration with the Human Brain Project consortium, it is accessible as a use case on the EBRAINS Cellular Level Simulation Platform.

Mouse Somatosensory Cortex

To build a mouse somatosensory cortex microcircuit, the biophysically detailed electrical models developed for the Allen Brain Institute – Blue Brain Project collaboration were adapted to be used in morphologies that were scaled to match the size of mouse neurons. The 941 electrical cell models used in this first draft release of the microcircuit is part of the Blue Brain collaboration with the Human Brain Project consortium. They are available on the EBRAINS Cellular Level Simulation Platform.

Thalamus studio

Thalamoreticular circuitry plays a key role in arousal, attention, cognition, and sleep spindles, and is linked to several brain disorders. A detailed computational model of mouse somatosensory thalamus and thalamic reticular nucleus has been developed to capture the properties of over 14,000 neurons connected by 6 million synapses. The model recreates the biological connectivity of these neurons and simulations of the model reproduce multiple experimental findings in different brain states. The model shows that inhibitory rebound produces frequency-selective enhancement of thalamic responses during wakefulness. We find that thalamic interactions are responsible for the characteristic waxing and waning of spindle oscillations. In addition, we find that changes in thalamic excitability control spindle frequency and their incidence. The model is made openly available to provide a new tool for studying the function and dysfunction of the thalamoreticular circuitry in various brain states.