Figure 1

Experimental design. A: Diagram showing experimental setup and protocol. Filled circle labeled “E” is a site at which a bipolar stimulating electrode is placed into contact with the layer 6/white matter junction. Rectangle encloses the cortical column-shaped region activated most vigorously by repetitive electrical stimulation applied via the electrode at E. Open triangle depicts an upper layer pyramidal neuron whose activity is recorded with whole-cell patch clamp recording electrode and amplifier. Micropipette filled with GABA is shown at top left with its tip in an extracellular position in close proximity to the recorded pyramidal neuron – a position enabling pressure-ejection (“puff”/local extracellular release) of GABA at selected times subsequent to the application of repetitive excitatory afferent drive at the L6/WM site contacted by the stimulating electrode. B: Representative example of column-shaped OIS response to the L6/WM stimulus (20-200 μA pulses delivered at 20 Hz).