Figure 5.

Dual whole-cell recordings in the hippocampal organotypic slice culture. A, Two filled cells demonstrating extensive apical and basal dendrites that extend across the physical dimensions of the slice from a dual whole-cell recording on DIV 5 in which pipettes contained AlexaFluor-594 (10 μm). B, Seizure activity in dual whole-cell recordings at DIV 11 (ictal data were not used for correlation). sEPSCs recorded 30 s after seizures (bottom, zoomed in recordings) were used for correlations. C, sEPSC correlations between neurons increased from 0.05 on DIV0 to 0.2 on DIV 15–19, consistent with increased connectivity as suggested in A. However, the correlation between neurons did not decrease with distance. The average cross-correlations are as follows: 0.05 ± 0.01 (DIV 1, gray dots, n = 22 pairs), 0.12 ± 0.01 (DIV 5, cyan triangles, n = 32 pairs), 0.18 ± 0.02 (DIV 8, dark red squares, n = 24 pairs), and 0.14 ± 0.02 (DIV 11, red dots, n = 21 pairs). D, Recording from a pair of CA3–1 pyramidal neurons that were considered to be synaptically connected based on the temporal correlation between action potentials in the presynaptic neuron (“pre”; action potentials widened by cesium pipette solution) and excitatory evoked responses evoked from resting membrane potential in the postsynaptic neuron (“post”; also recorded with cesium pipette solution).