Figure 4.

Synaptic physiology of human subplate neurons. A, Schematic of an acute brain slice. The synaptic stimulation electrode (syn. stim.) was moved between three locations: below, above, or lateral to the SP neuron. B, Failed responses to synaptic stimulation. C, Outcomes of the (1) synaptic shocks (Synaptic), (2) glutamate iontophoresis (Glut.), and (3) GABAergic applications (GABA) expressed by number of SP neurons that had no response (None), or experienced positive (EPSP; Depol.) or negative (IPSP; Hyper.) membrane potentials. Asterisks indicate zero count. D, Synaptically evoked EPSP—two successes, four failures. Three shocks were delivered at 50 Hz (syn. ×3). E, Synaptically evoked IPSP—2 successes. Data are from a different cell with the same stimulation settings as in D. F, Left, During the experiment, the glutamate iontophoresis electrode was moved (dashed arrow) from the location near the soma (Glut. 1) to another position, near the apical dendrite (Glut. 2). The pia is toward top right. Scale bar, 20 μm. Right, Glutamate-evoked membrane potential transients—eight increments in iontophoretic current intensity, 1–8. Inset, Glutamate-evoked burst of APs. Calibration: 200 ms. G, Spontaneous firing of APs is stopped by focal application of GABA. Inset, Experimental paradigm for local GABA application.