Figure 1. Selection and application of the stimulation sequence and network frequency-dependent modifications.

A) The activity recorded from one electrode is chosen for the design of the spike pattern stimulation (see right traces). After network stabilization, its activity is extracted over a period of 2 min and a spike detection algorithm is applied to extract its spike timing pattern. A train of biphasic rectangular voltage pulses (750 mV, 250 µsec for phase, positive phase first) is built based on the spike pattern of the designed electrode and delivered through it. Three distinct stimulation protocols of the same duration (see right traces) are alternatively applied: single (SS), repetitive stimulation (RS) and Poisson stimulation (POISSON). B) Conditional Firing Probability (CFP): function and relative parameters. Left: A representative CFP histogram (black profile) and the relative fitting (red profile) between two channels during a ‘SHAM’ condition. Right: Extraction of the main parameters from the fitting of the CFP by using the equation 1 (cf. Methods section). The strength represents the maximum probability above offset, the width is computed as the amplitude of the peak at the height ‘offset+0.8 strength’, and the offset refers to background noise and unrelated background activity.