Figure 8.

Reduction of synaptic inhibition in the dendrites of granule cells in pilocarpine-treated mice. A, Ten superimposed traces of asynchronous IPSCs evoked in the presence of 2 mm Sr²⁺ recorded in a control and a pilocarpine-treated (Pilo) granule cell. The areas shaded in gray indicate the 100 ms time windows after the stimulation in the molecular layer, during which the asynchronous IPSCs were detected and analyzed. The single expanded trace is an example of the events during the 100 ms window. B, Averaged sIPSCs (left) recorded in a representative control and a pilocarpine-treated granule cell were superimposable. In contrast, the averaged asynchronous IPSCs (Sr-IPSCs) evoked by stimulation of dendritic afferents (right) in two different cells were smaller in the pilocarpine-treated granule cell. C, Summary data showing the similarity between the average amplitudes of sIPSCs recorded in the two preparations (56.1 ± 5.0 pA in control; 58.6 ± 2.8 pA in Pilo; p = 0.7, unpaired t test) and the smaller amplitude Sr-IPSCs (p = 0.005; unpaired t test) in the pilocarpine-treated granule cells (42.1 ± 6.0 pA, n = 11 cells in control; 30.2 ± 3.1 pA, n = 11 cells in Pilo). D, Individual cumulative probability plots of the Sr-IPSCs recorded in control (thin black lines) and pilocarpine-treated granule cells (thin gray lines). The cumulative plots of all the events are indicated by thick black lines for both preparations. Note the significantly larger Sr-IPSCs in control preparations indicating larger synaptic inhibition in the dendrites of control granule cells than that of the pilocarpine-treated animals.