Figure 3.

Neutron irradiation alters long-term synaptic plasticity in the hippocampal area CA1 and ventral medial prefrontal cortex. A, B, Extracellular field recordings following stimulation of the Schaffer-commissural projections to the proximal apical dendrites of field CA1b of the dorsal hippocampus, 6 months following completion of the 18 cGy neutron irradiation. A, Following a stable 20 min baseline recording, a single train of TBS was applied and baseline recordings were resumed for an additional 60 min. The time course shows that TBS-induced LTP was markedly reduced in slices from irradiated mice compared with slices from 0 cGy control mice. Inset, Representative traces collected during baseline (solid line) and 60 min post-TBS (dotted line). B, Field EPSP slope was significantly reduced 60 min post-TBS in slices from the neutron-irradiated mice compared with controls. C, D, Field responses recorded in cortical layer III following stimulation of glutamatergic inputs in cortical layer IV of the ventral medial prefrontal cortex. C, Similar results were obtained as shown in A. TBS-induced LTP was nearly completely blocked in slices from neutron-irradiated mice relative to controls. Inset, Representative traces collected during baseline (solid line) and 60 min post-TBS (dotted line). D, Field EPSP slope was significantly reduced 60 min post-TBS in slices from 18 cGy mice compared with controls. N = 9 slices per group. ***p < 0.0001 (two-tailed t test).