Figure 9.

Factors that determine neuronal membrane potential. Illustrated are (A) a schematic diagram of currents flowing into and out of neurons, and the dependency of (B) leaking currents, (C) excitatory neuron firing rates (F_E), (E) excitatory synapse efficiency (|S_E|), (D) inhibitory neuron firing rates (F_I), and (F) inhibitory synapse efficiency (|S_I|) on membrane potentials. Synaptic efficiency is defined as $|S_{\mathrm{p}}|=|g_p(V_p^{[\mathrm{rev}]}-V_q)|$, where g_p is the synaptic gain, V_q is the membrane potential of the postsynaptic neuron, $V_p^{[\text{rev}]}$ is the reversal membrane potential and set to 0 mV for excitatory synapses and −70 mV for inhibitory synapses. The figures are plotted in arbitrary units. Acronyms: EPSC–excitatory postsynaptic currents, IPSC–inhibitory postsynaptic currents.