neural disturbances, e.g., to suppress undesired synchrony of firing neurons in Parkinson’s disease or epilepsy [@SCH94e; @ROS04a; @POP05]. Chaos control techniques have been first applied experimentally [*in vitro*]{} in a spontaneously bursting neural network [@SCH94e] using a method proposed by Ott, Grebogi and Yorke [@OTT90]. In contrast to this method, the time-delayed feedback method by Pyragas [@PYR92] and its extensions [@SOC94] do not require detailed information on the system to be controlled, and they are non-invasive, i.e., once the target state is reached, the control force vanishes. However, one needs to tune the feedback gain and the delay time. Therefore, theoretical investigations help to understand optimal choices of these parameters. Various global delayed feedback schemes have been proposed as effective and robust therapy of neurological diseases with pathological synchronization causing tremor [@ROS04a; @POP05]. They have been contrasted with [*local*]{} delayed feedback methods [@GAS07b; @GAS08; @DAH08].

![(a) Scheme of two axo-axonally coupled neurons (pyramidal cells coupled by an electrical synapse) [@SCH01e]. (b) Two mutually coupled neural populations (delay $\tau$, coupling constant $C$) with feedback control loop (delay $\tau_K$, coupling constant $K$) and noise input $D_1$, $D_2$.[]{data-label="fig:scheme"}](fig01.eps){width="50.00000%"}

Neurons are excitable units which can emit spikes or bursts of electrical signals, i.e., the 