Coexistence of amplitude and frequency modulations in intracellular   calcium dynamics
  The complex dynamics of intracellular calcium regulates cellular responses to information encoded in extracellular signals. Here, we study the encoding of these external signals in the context of the Li-Rinzel model. We show that by control of biophysical parameters the information can be encoded in amplitude modulation, frequency modulation or mixed (AM and FM) modulation. We briefly discuss the possible implications of this new role of information encoding for astrocytes. 
Maurizio De Pitta, Vladislav Volman, Herbert Levine, Giovanni Pioggia,   Danilo De Rossi, and Eshel Ben-Jacob