Top-down modulation in canonical cortical circuits with short-term plasticity.

Area of Science:

• Neuroscience
• Computational Neuroscience
• Systems Neuroscience

Background:

• Cortical computations rely on diverse GABAergic interneurons (parvalbumin, somatostatin, vasoactive intestinal peptide) interacting with excitatory neurons.
• These networks exhibit nonlinear phenomena, such as response reversal, where neuronal responses change based on input context and neuromodulation.

Purpose of the Study:

• To investigate how short-term plasticity mechanisms in multi-interneuron networks contribute to nonlinear phenomena like response reversal.
• To elucidate the specific roles of different interneuron subtypes and their plasticity in network dynamics and stabilization.

Main Methods:

• Employed analytical and computational modeling approaches.
• Incorporated experimentally identified short-term plasticity mechanisms into network models with multiple interneuron subtypes (PV, SST, VIP) and excitatory neurons.

Main Results:

• Model networks successfully implemented response reversal, where somatostatin (SST) neuron responses to vasoactive intestinal peptide (VIP) modulation depended on sensory input.
• Short-term depression from parvalbumin (PV) to excitatory (E) neurons significantly impacted SST response reversal, despite not directly influencing SST or VIP activity.
• Response reversal was linked to changes in network stabilization mediated by SST neurons, highlighting the role of plasticity in network state transitions.

Conclusions:

• Short-term plasticity mechanisms are crucial for generating nonlinear phenomena in cortical networks with multiple interneuron types.
• PV-to-E short-term depression plays a critical, albeit indirect, role in SST response reversal and network stabilization.
• The study provides experimentally testable predictions regarding the interplay of interneuron subtypes and short-term plasticity in cortical function.