Cortical neurons are constantly bombarded with synaptic inputs during various behavioral states.Summation of postsynaptic potentials results in voltage fluctuations in the soma and generation of action potentials in the axon when a firing threshold has been reached.It has been shown that membrane potential changes in the presynaptic soma could modulate intracortical synaptic transmission triggered by action potentials.Here we demonstrate that membrane potential changes in a single layer 5 pyramidal neuron control the size of its local circuitry.Somatic depolarization recruits more nearby cortical neurons,including pyramidal and non-pyramidal neurons,in a local circuit activated by a burst of action potentials (100-200 Hz) in the recorded neuron.Modest depolarization (10-15 mV) enhances recurrent excitation and feedback inhibition.