Characteristics of EPSCs in L3.

<p>A. Voltage clamp recordings from one neurone show that the AMPAr antagonist NBQX essentially abolished sEPSCs. At more positive holding potentials, occasional, slow sEPSCs were detected that were mediated by NMDAr, as they were blocked by 2-AP5. B. A comparison of sEPSC properties Showed that the mean frequency of events in L3 was greater than that in either L2 or L5. Amplitudes were similar across layers, but kinetics (C) were slower in L2 compared to the deeper layers. D. Action potential driven release accounts for a much higher proportion of spontaneous excitation in L3. Cumulative probability analysis of data pooled from 10 neurones (graph on left) showed a large increase in IEI (shift to the right) in L3 that was substantially greater than that seen in L2 or L5. This is very clearly illustrated by the bar graphs (right) showing the accompanying change in frequencies (sEPSC frequency minus mEPSC frequency). E. Neither amplitude nor kinetics of EPSCs in the same neurones were significantly different in the presence of TTX (mEPSCs shown in blue).