Figure 4: Mechanism-I by which spike bursting destroys network oscillations.
(A) The network which is initially in an oscillatory state switches to a non-oscillatory state with the replacement of FS neurons (orange dots) with the BS neurons (grey dots) in the inhibitory population. The blue dots show the excitatory spikes and the dark blue line is the z-scored PSTH of the excitatory activity. The light brown stripes correspond to the crest of the oscillatory cycles of the excitatory population when the network consisted of only FS inhibitory neurons. The number of additional spikes that fall within the stripes (numadd) is added (g = 12, d = 2 ms, η = 11500 sp/s, F = 0.4, E : I ratio = 4 : 1). (B) A schematic to depict how additional inhibitory spikes (red dots) when the inhibitory oscillatory cycle wanes makes the oscillatory activity unstable in an ING oscillation. The excitatory population (blue dots) oscillates in the window of opportunity provided by the inhibitory population (orange dots). The red dots indicate the additional inhibitory spikes that are added. (C) PSTHs of the excitatory population shows the changes after the addition of the numadd spikes in the inhibitory population. When the spikes are added when the inhibitory oscillatory cycle tapers off there is maximum disturbance of succeeding oscillatory cycles (blue line). When the same number of spikes are added at the peak of the preceding oscillatory cycle, there is minimal effect on the subsequent oscillatory cycle (Control-dark blue line). The pale blue line shows the baseline activity when no spikes are added (g = 12, d = 2 ms, η = 11500 sp/s).(D) Same as in (C), except that the oscillations are PING driven. (E) PSTHs of the excitatory population affected by additional spikes in a PING driven oscillation (g = 7, d = 1.5 ms, η = 20000 sp/s).
