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. Author manuscript; available in PMC: 2012 Oct 20.
Published in final edited form as: Neuron. 2011 Oct 20;72(2):231–243. doi: 10.1016/j.neuron.2011.09.027

Figure 2.

Figure 2

Proportionality of excitation and inhibition during stimulus-evoked and spontaneous cortical activity. A, Intracellular recording of responses to drifting gratings of different orientations in cat visual cortex. Peristimulus time histograms of spike rate reveal the strongest increases in firing of the cortical neuron to a stimulus orientated at 90° (“preferred stimulus”). Measurements of changes in excitatory (red) and inhibitory (blue) synaptic conductance from the same recording reveal that both excitation and inhibition are tuned to the same orientation. Modified from (Anderson et al., 2000). B, Simultaneous intracellular recordings of spontaneous synaptic activity from two nearby neurons in rat somatosensory cortex. One cell (red trace) is hyperpolarized at the reversal potential for inhibition to reveal excitatory postsynaptic potentials (EPSPs) and the other (blue trace) is depolarized to reveal inhibitory postsynaptic potentials (IPSPs). Spontaneously occurring EPSPs (monitored in one cell) are accompanied by IPSPs (monitored in the neighboring cell) of co-varying amplitude. Modified from (Okun and Lampl, 2008).