Determining synaptic input properties from intra-cellular recordings in vivo

A cortical neuron in vivo is bombarded with excitatory and inhibitory inputs that eventually underlie the neuron's activity. The transformation between input and output, which is determined by the synaptic integration and the action potential generation, is core to neural information processing and neural coding. However, despite its importance the precise transformation between input and output is unclear.
Although it is currently impossible to exactly measure all the presynaptic spike trains to a specific neuron, much can be learned from recordings of the post-synaptic membrane potential. In this study we outline a procedure to estimate the presynaptic activity based on the statistics of the membrane voltage obtained in in-vivo patch- clamping experiments. In particular, we include analysis of the power-spectral density and the frequency of events of a certain size.
We apply the above procedure to measurements of the membrane voltage fluctuations in motor cortex of awake mice during the resting state and a spontaneous movement state. The results allow us to suggest an explanation for the observed changes between the two states.