Fig. 4.

A, A 3 DIV Xenopus culture with a perforated-patch recording electrode (right side) and a pipette containing glutamate to be puffed onto the cell (left side). Spontaneous synaptic currents are not detectable at this stage in culture. B, Electrophysiological recordings from a single cell in response to identically puffed glutamate in the presence of various glutamate receptor blockers. Blockade of type II mGluRs alone using EGLU causes a substantial increase in glutamate response in this neuron, whereas CNQX decreases the glutamate response. Combined type II mGluR and AMPA/KAR blockade (EGLU+CNQX) decreases glutamate response by a larger amount than CNQX alone. These results are consistent with the calcium imaging results reported in Figure 3, and the results of recording from several cells are summarized in Table 1.