FIGURE 2. Correlation probabilities for EPSCs and IPSCs in layer 2/3 pyramidal cell pairs.
From the following article:
Excitatory cortical neurons form fine-scale functional networks
Yumiko Yoshimura, Jami L. M. Dantzker and Edward M. Callaway
Nature 433, 868-873(24 February 2005)
doi:10.1038/nature03252
a, b, Correlation probabilities for EPSCs (a) and IPSCs (b) are shown separately for photostimulation sites in each cortical layer and for connected (circles) versus unconnected (squares) pairs of cells. Open circles correspond to pyramidal cells that were reciprocally connected and filled circles indicate one-way connections. Mean values for each group are indicated by horizontal lines. c, d, An experiment testing connections between pyramidal cell pairs (c) and summary of results (d). Action potentials were triggered by injecting positive current into one current-clamped cell (upper traces) while recording EPSCs in the other voltage-clamped cell (lower traces, 3 examples shown for each). The cell pair illustrated in c had a one-way connection from 'cell b' to 'cell a'. Connections, when present, were highly reliable for both layer 4 to layer 2/3 (4% failure) and layer 2/3 to layer 2/3 (8% failure) pairs. Connections were found in 20% of cell pairs for both layer 4 to layer 2/3 and layer 2/3 to layer 2/3 pairs.