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. 2005 Apr 20;25(16):4040–4051. doi: 10.1523/JNEUROSCI.4115-04.2005

Figure 2.

Figure 2.

Effect of diminished activity on neuron-neuron connectivity. A, Representative double whole-cell recordings in cultured hippocampal pyramidal neurons at 18 DIV. Neuron-neuron connectivity in control (Ctrl) and TTX-treated (TTX) neurons is shown. Total synaptic connectivity (the ratio of paired neurons connected by silent and functional synapses to total recorded paired neurons) was measured by double whole-cell recording (B, left). Silent synaptic connectivity and functional synaptic connectivity (B, middle and right) were also measured. Both silent and functional synaptic connections were increased 270 and 240%, respectively, by TTX treatment (12 series of experiments; **p < 0.05). C, Representative double whole-cell recordings of paired neurons with functional (left, pre) and silent (right, post) synaptic connections in TTX-treated neurons. Each trace is an average of five successive responses from a stimulated presynaptic and postsynaptic neuron at -60 or +40 mV holding potentials. EPSCs in silent connections at +40 mV holding potential were completely blocked by 1 μm ifenprodil.