Figure 3.

Iontophoresis of l-glutamate evoked action potentials and synaptic potentials in patch-clamped SC neurons. A, A patch-clamped neuron (current-clamp mode) near the site of l-glutamate application responded directly with a depolarization and action potentials to l-glutamate application < 100 μm from the recording. In A and B the narrow iontophoretic pipette labeled Glu indicates the site of l-glutamate application and the wider patch pipette indicates the location of the neuron under recording. B, An SGI neuron responded with synaptic potentials to l-glutamate application in the SGS (in 5 of 12 neurons). Three voltage traces show three consecutive trials, with the neuron under recording responding with a burst of subthreshold EPSPs. C, A diagram depicting the locations of all 12 neurons from which recordings were made. Numbered black circles denote glutamate-unresponsive neurons and orange circles denote glutamate-responsive neurons. The sites of application are indicated in the SGS corresponding to each numbered neuron. The iontophoretic pipette contained 1 m l-glutamate and delivered 1 s, 500 nA pulses in each trial (bar below each trace).