Semiconductor circuits are provided for emulating neuron firing process using a positive feedback transistor having first and second gate electrodes in the longitudinal direction of a channel region. The first gate electrode is connected to a gate electrode of a first p-channel MOSFET to be an input terminal and the second gate electrode is connected to a drain to be applied with a supply voltage. Thus electrons and holes can accumulate separately in a channel region (i.e., a body) under each of the gate electrodes by applying input signals to the input terminal and drastically reduce the wasted power consumption in the non-fired neurons because the current is turned on and off only at a moment that corresponds to a firing of the neuron. Thus, the semiconductor circuits can be driven by low power and have the same level of endurance as a general MOSFET.