Stimulation with ECoG electrodes modulates cortical activity and sensory processing in the awake mouse brain

Area of Science:

• Neuroscience
• Computational Neuroscience
• Systems Neuroscience

Background:

• Electrical stimulation is crucial for studying neural networks and treating brain dysfunction.
• Electrocorticography (ECoG) electrodes offer chronic, minimally invasive brain stimulation.
• The precise impact of cortical surface electrical stimulation on neural network activity is not well understood.

Purpose of the Study:

• To investigate how cortical surface electrical stimulation modulates neural activity in the awake mouse visual cortex.
• To determine the effects of electrical stimulation on neuronal responses during concurrent visual stimulation.
• To elucidate the circuit mechanisms underlying the observed modulations.

Main Methods:

• In vivo calcium imaging in awake mice with chronically implanted ECoG electrodes.
• Measurement of visual cortical neuron activity during electrical and visual stimulation.
• Analysis of inhibitory interneuron subtype (PV, SST, NDNF) responses.

Main Results:

• Cortical surface electrical stimulation caused initial L2/3 neuron activation followed by prolonged inhibition.
• Electrical stimulation suppressed neuronal responses to preferred visual stimuli while enhancing responses to non-preferred stimuli, reducing feature selectivity.
• A proposed circuit model identified strong activation of L1 NDNF interneurons by electrical stimulation, leading to inhibition of L2/3 excitatory neurons and PV interneurons via GABA volume transmission.

Conclusions:

• Cortical surface electrical stimulation significantly alters visual cortical network dynamics, impacting neuronal excitability and sensory processing.
• The findings suggest a specific circuit mechanism involving L1 NDNF interneurons in mediating the effects of electrical stimulation.
• This study provides critical insights into the functional consequences of ECoG-based brain stimulation.