Homogeneous inhibition is optimal for the phase precession of place cells in the CA1 field
Place cells are hippocampal neurons encoding the position of an animal in space. Studies of place cells are essential to understanding the processing and transmission of information by neural networks of the brain. An important characteristic of place cell spike trains is phase precession. When an animal is running through the place field, the discharges of the place cells shift from the ascending phase of the theta rhythm through the minimum to the descending phase. The role of excitatory inputs to CA1 pyramidal neurons along the Schaffer collaterals and the perforant pathway in phase precession is described, but the role of inputs from local interneurons to CA1 pyramidal cell is poorly understood. We have set the goal the contribution of field CA1 interneurons to the phase precession of place cells using mathematical methods. The CA1 field was chosen because it provides the largest set of experimental data required to build and verify the model. We have solved the optimization problem and found the parameters of the excitatory and inhibitory inputs to the pyramidal neuron of the CA1 field so that the neuron generates a spike train with the effect of phase precession. We have discovered that the uniform inhibition of field CA1 pyramidal neurons best explains the effect of phase precession. Among interneurons, axo-axonal neurons make the greatest contribution to the inhibition of pyramidal cells.