Implementation of adaptive neuron based on memristor and memcapacitor emulators

Adaptive response to timely constant stimuli is a common feature of biological neurons. Implementation of neurons with such features is important for achieving biologically plausible networks using electronic systems. Emerging memristor devices open new horizons in electronically implementation of neural networks with high integration density and low power consumption. Promising potential applications can be considered for mem-elements (memristor, memcapacitor, and meminductor) with their built-in memory-properties. Since the dynamics of mem-elements makes them suitable for direct emulation of biological features of real neurons, it is expected that implementation of real neurons with complicated behavior to be straightforward using mem-element without complicating the implementation of the whole neuron circuit. Mem-elements are still unavailable commercially, so we utilize the mem-elements emulators to evaluate the feasibility of using these elements in the implementation of adaptive neurons. To ensure that there is the possibility of practical implementation of our neuron circuit, we used mem-elements emulators in SPICE simulations instead of mem-elements behavioral models. This work is among the first papers in the implementation of adaptive neurons using mem-elements. Here, using memristor and memcapacitor emulators the neuristor with adaptive behavior is implemented in SPICE environment. We use two different methods for induction of adaptive behavior to the neuristor response. In the first method, the capacitor in the primary circuit of neuristor is replaced with memcapacitor. Alternatively, the coupling resistor in the primary circuit of neuristor is replaced with the memristor in the second method. Results show that, the feature of memristor/memcapacitor in changing its resistance/capacitance during time upon excitation with current or voltage, makes the neuristor behavior to be adaptive in both methods, i.e. the neuristor shows the spike-frequency adaptation behavior in response to the continuous external stimulus, where the frequency of generated spikes depends on the duration of the external input stimulus.