Cortical cell assemblies and their underlying connectivity: An in silico study

Area of Science:

• Neuroscience
• Computational Neuroscience
• Systems Neuroscience

Background:

• Simultaneous recordings from thousands of neurons allow studying functional cell assemblies.
• Determining synaptic connectivity patterns underlying these assemblies is challenging.

Purpose of the Study:

• To develop a simulation-based approach using a large-scale cortical network model to study functional cell assemblies.
• To investigate how synaptic connectivity structure influences assembly composition and activation.

Main Methods:

• Detected functional cell assemblies from stimulus-evoked spiking activity of 186,665 neurons using a detailed cortical network model.
• Quantified the effects of thalamic innervation, recurrent connectivity, and dendritic synapse arrangement on assembly composition.

Main Results:

• Synaptic connectivity features reduced uncertainty in neuron assembly membership by up to 30%.
• Assemblies were activated in stimulus-specific sequences and grouped by temporal order.
• Connectivity's predictive power increased with temporal alignment, population interconnectedness, and dendritic clustering.

Conclusions:

• Synaptic connectivity patterns, not just amount but also local structure, are crucial for assembly emergence.
• Reversed Hebb's postulate: cells wired together fire together, with connectivity shaping assembly dynamics.
• Subcellular and network-level connectivity details influence functional cell assembly formation.