Fig. 1.

Normal long-term potentiation (LTP) and deficient synaptic scaling in visual cortical slices prepared from TNFα knockout mice. (A) LTP is normal in Tnf−/− mice (n=6) compared to wild type mice (n=9). The peak amplitudes of field excitatory postsynaptic potentials (fEPSP) recorded in layer 3 in response to layer 4 stimulation are plotted as a function of time. Theta burst stimulation (TBS) was delivered at time 0. Insets on the right show example traces of fEPSP (averaged responses (6 traces = 1 minute) from around 1 and 2 in the graph. The smaller trace is pre-LTP (1) and the larger trace post-LTP (2). (B-D) Homeostatic synaptic scaling assayed in organotypic slice cultures of mouse visual cortex prepared from Tnf−/− and Tnf+/+ mice. The amplitudes of miniature excitatory postsynaptic currents (mEPSC) are increased after 2 days of blockade of glutamatergic excitatory transmission (using CNQX/APV) in Tnf+/+ mice but not in Tnf−/− mice (n = 10 – 13 cells per condition).