Synaptic Reorganization of the Perisomatic Inhibitory Network in Hippocampi of Temporal Lobe Epileptic Patients

Figure 1

Light micrographs show the distribution of PV-containing interneurons in the human control (a) and epileptic (b–d) CA1 region. (a) Horizontal PV-positive cells (double arrowheads) are present in the stratum oriens (s. o.). Multipolar PV-positive cells (arrows) located in the stratum pyramidale (s. p.) send their dendrites to all layers (arrowheads). (b) In the nonsclerotic epileptic CA1 region (Type 1, mild) the number of PV-positive elements (somata and dendrites) has decreased, mainly visible in the stratum oriens. (c) In the nonsclerotic CA1 region with patchy cell loss (Type 2) the decrease in the number of PV-positive elements is even more pronounced. In several cases, surviving pyramidal cells (left side) accumulate the chromogene diaminobenzidine (giving aspecific staining), possibly due to cellular degeneration processes. (d) In the sclerotic CA1 region (Type 3) only a few PV-stained cells and dendrites are present. Scale bar: 50 μm.