Figure 4.

a, Network spikes recorded over a period of 2 h in the absence (left) and presence (right) of 5 μm bicuculline. These NSs were obtained using a threshold of three action potentials within a 10 ms time bin. Each black dot marks an action potential detected in any of the electrodes during the ±250 ms surrounding the NS threshold. NSs are ordered using a clustering algorithm to enhance visualization of bicuculline effects: a reduced number of aborted NSs and a more vigorous activity within each NS. b, An average NS obtained in the presence of 5 μm bicuculline (brown). Average NS in control solution is shown in black. Top right inset, Fitted fast declining phase in the presence of bicuculline, representing the timescale of cellular-level (intrinsic) restoring forces. Bottom right inset, Fitted slow declining phase of the control NS, representing the timescale of restoring force acting through the inhibitory subnetwork. Note the timescale separation between the two types of restoring forces involved (6.5 ms for the effect of cellular-level forces; 33.7 ms for the effect of the inhibitory subnetwork). c, Averaged phases of recruitments extracted from 16 experiments before (black) and after (brown) the addition of 5 μm bicuculline to the bathing solution. Each recording episode lasted 1–2 h. Broken lines depict 1 SD (one-sided for clarity). Thick lines depict segments for which a single-exponential recruitment function could be reliably fitted for both conditions; σ values obtained were 1.06 and 1.22 for control and bicuculline conditions, respectively.