Inhibitory Activity is Proportional to the Activity of the Network
To test the hypothesis that feedback inhibition is proportional to network activity, we plotted the amplitude of IPSCs arriving in a pyramidal cell voltage clamped to 0 mV against the amplitude of activity in the local network (A). There is a high correlation between the level of activity in the local network and the amplitude of inhibitory postsynaptic currents. B. The action potential activity of a single neuron is roughly correlated witht he activity in the multiple unit recording.
These data confirm that the amplitude of feedback inhibition in the network is proportional to the level of network activity (which should also be represented as the level of feedback excitation arriving in each neuron).