Figure 4.

Example of how multi-unit activity (MUA) recorded by an 8 × 8 Utah array propagates from a cortical point. Bursting spike activity in the MCx was produced by focal iontophoretic ejection at array coordinate (6, 4) of the GABA_A receptor antagonist Bicuculline. The maps of neural activity were calculated every millisecond from near the onset (t = 0 ms) of spontaneous bursts of ictal neural activity to the time at which the maximum cortical area was recruited (t = 19 ms). Activity continues for several tens of millisecond after that. Note the onset of activity at coordinate (6, 4) and the subsequent progressive recruitment of cortical territory with time. In this example activity was evoked at 62 out of 64 possible electrodes. The recruited cortical area was 7.6 mm², or 96% of the area covered by the array [reproduced with permission from Capaday et al. (2011)].