Figure 7.

Illustration of synaptic blockade subtraction algorithm. (A) Photograph taken at ×5 of cortical slice with overlay of current traces at several photostimulation sites obtained in normal ACSF. Recording electrode location is outlined with white dotted lines. Recorded cell is held in voltage clamp at −40 mW. (B) Same stimulation sites with tissue bathed in 0 mM CaCl₂ and 4 mM MgCl₂. Scale bar = 500 μm. (C) Overlay of current traces at site in layer 2/3 with red arrow. Blue trace obtained in normal ACSF, black trace obtained in low calcium/high magnesium. Red trace is the difference of the normal ACSF and the low calcium/high magnesium traces. (D) Same description as (C) but for site in layer 5 with blue arrow.