We have studied the response of simple networks of relaxation oscillatory electrode pairs to inputs through external cells. Such networks are shown to respond to constant inputs by decreasing or increasing the period depending whether the connection with the external cell is excitatory or inhibitory. The response to pulse inputs is determined by the phase of the relaxation oscillations; within the refractory region the network remains unaffected whereas within the excitable region an increase in the period is observed accompanied by the induction of new peaks. (C) 2002 Elsevier Science B.V. All rights reserved.