Fig. 1.

LTP of excitatory synapses onto neocortical layer 5 pyramidal neurons. (A) Infrared DIC image of a patch-clamped layer 5 pyramidal cell (Top) and schematic illustration of the recording and stimulation configuration (Bottom). (B) Illustration of the stimulation protocol used to assess short-term plasticity changes associated with LTP induction in layer 5 pyramidal neurons. Inputs were repeatedly stimulated extracellularly with 50 Hz trains consisting of 30 stimuli followed by single stimuli delivered at various time intervals after a conditioning 50 Hz train to probe recovery from short-term depression. In addition, paired-pulses with 20 ms interstimulus interval were applied after 20 s. This stimulation pattern (train + paired-pulses) was repeated every 45 s for 10 min. To induce LTP, pre- and postsynaptic activities were paired while recording in current-clamp configuration. (C) Three example experiments of LTP inducible connections (green), non-inducible connections (blue), and control cells (gray, receiving no LTP induction). (D) Normalized mean EPSC amplitudes of inducible connections, non-inducible connections, and control cells before and after LTP induction. (E) Individual and median EPSC amplitudes of inducible connections and non-inducible connections, of the merged dataset (inducible and non-inducible connections), and of a control group (no stimulation). (F) Box plot and individual data points of the change in EPSC amplitude (after/before) of inducible, non-inducible, and control connections.