Figure 3.

Current-evoked responses on an MEA substrate and the time courses of LTD before and after tetanic stimulation (TS). (A) In a slice of the mouse neocortex, evoked LFPs were extracellularly recorded prior to and posterior to TS on the MEA substrate. Thin, thick, and dotted lines, respectively, represent the LFP response waveforms at 5 min before tetanic stimulation (pre-TS, −5 min), immediately after the tetanic stimulation (post-TS, 0.5 min), and 60 min after the tetanic stimulation (post-TS, 60 min). Averaged LFP responses were evoked via current test stimulation at a single electrode site (ch. 26), which was in layer 4 and the same electrode to which the tetanic stimulation was applied. The stimulation current intensity was 25 μA. (B) For the horizontal three electrode sites to the stimulation site (ch. 26) under the same brain slice in A, the time courses of LTD for the tetanic stimulation applied at time 0 min are shown. The inter-electrode distances (IEDs) between the electrode site (ch. 26) of the test stimulation and each of the recording sites (chs. 27, 29, and 31) were 150, 450, and 750 μm, respectively. (C) As the control condition (normal extracellular medium), average time courses of LTD from group data (n = 5) were illustrated. Response peak amplitudes posterior to the TS were normalized by those prior to the TS. The IEDs between the electrode site (e.g., ch. 26) of the test stimulation and each of the recording sites are also indicated.