Selective recruitment of cortical neurons by electrical stimulation
Fig 6
Numerical simulations predict that feedback inhibition controls response properties.
(a): Schematic representation of the network model structure, which consists of 3 types of cells, located in 3 different layers (canonical circuit). PY stands for pyramidal neuron, SpS–spiny stellate cell, BC–basket cells, MC–Martinotti cells. Lines with circles denote excitatory AMPA connections (solid–strong, dashed—weak), whereas bars denote inhibitory GABA connections. (b): Two electrophysiological classes of neurons were used in our simulations: top voltage trace (green) corresponds to regular spiking neurons (used for pyramidal, spiny stellate cells and Martinotti cells) and bottom voltage trace demonstrates activity of fast spiking interneurons (used for basket cells). (c): Spike raster plots exhibit network activity for cathodal (left panel) and anodal (two right panels) stimulations. The cells were activated during first 1 ms of simulation according to activation probability (see text for details). Green dots–PY and SpS cell spikes, red dots–interneuron spikes. Left panel shows weak response to cathodal stimulation (-100 μA). Middle panel shows response to moderate anodal stimulation (75 μA), which induced a large population response. The right panel shows response to a strong positive current (300 μA), which activated a large number of basket cells in layer II/III and Martinotti cells in all layers, which prevented the activation of excitatory cells in layers II-IV. (d, e): Population responses as a function of net electrode current for layer II-IV excitatory cells.