Figure 2.

Both spine expansion and LTP require postsynaptic spiking during theta burst stimulation. A, The expression of LTP depends on postsynaptic spiking, as shown in representative experiments. A1, Top, Sample voltage traces showing spiking activity triggered by EPSPs during TBP (top), and subthreshold EPSPs during TBS (bottom). Calibration: 25 mV, 25 ms. Bottom, Sample EPSP traces before and after TBP (left) or TBS (right). Calibration: 3 mV, 20 ms. A2, The same experiments as in A1 are shown, with EPSP slope plotted as a function of time. B, A summary of TBS experiments showed that TBS on its own did not alter synaptic transmission. C, No significant spine expansion was observed after TBS. Error bars indicate SEM.