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. 2007 Aug 1;2(8):e670. doi: 10.1371/journal.pone.0000670

Figure 3. Paired pulse facilitation in up versus down states in the cortex in vitro.

Figure 3

A. Six up states interspersed with down, silent states recorded from a layer 2/3 neuron in primary visual cortex of the ferret in vitro. B. Four up states (top trace) and the corresponding multiunit activity recorded in the vicinity of the neuron (bottom trace). The intracellular recordings were kept subthreshold by means of current injection. C. Expanded up state illustrating the time segments that will be used to sort out the time of occurrence of the PSPs: Down (down state periods excluding the 200 ms following an up state), In (up states) and End (200 ms following the occurrence of the up state). D. Raw traces of a pair of PSPs occurring during the Down, In and End periods (top trace). Averaged paired PSPs for the same neuron during the 3 periods with respect to the occurrence of the up states: Down, In and End (bottom trace) (n = 8 PSPs have been averaged for each segment). E. Bar diagram illustrating the amplitude of the first and second PSP of the pair during the 3 time segments (Down, In and End) for intracortical synapses recorded in vitro. All the PSPs have been normalized with respect to the first PSP of the pair in the down states (n = 9 neurons).