Spontaneously active cells induce state transitions in a model of olfactory cortex

Area of Science:

• Neuroscience
• Computational Neuroscience
• Systems Neuroscience

Background:

• Neurons with intrinsic oscillations are crucial for neural population synchronization.
• Coupling via chemical and/or electrical synapses is essential for pacing population rhythms.

Purpose of the Study:

• Investigate the role of spontaneously active cells (noisy or pacemaker units) in establishing global oscillations within a three-layered cortical model.
• Determine how the characteristics of these active units influence network behavior and oscillation onset.

Main Methods:

• Simulated a three-layered cortical network model.
• Introduced spontaneously active units (noisy and/or pacemaker) with varying types (excitatory/inhibitory) and numbers.
• Analyzed network-level oscillations, including gamma rhythm emergence, regularity, and onset dynamics.

Main Results:

• A small number of noisy, spontaneously active units induced gamma rhythm oscillations at the network level.
• The quantity and type of noisy units determined whether regular oscillations or chaotic behavior emerged.
• Replacing noisy units with pacemaker units also generated gamma oscillations; their interplay affected the delay to global activity onset.

Conclusions:

• Spontaneously active neurons, whether noisy or oscillatory, can generate global brain oscillations without external stimuli.
• These findings support the role of intrinsic neuronal activity in establishing cortical rhythms, potentially linked to functions like memory and attention.
• The study highlights the importance of neuronal intrinsic properties and network connectivity in shaping emergent network dynamics.