Table 4.

Conversion of current to glutamate and GABA concentration in ex vivo recordings.

Points1	Glutamate Signal (pA)2	Glutamate (μM)3	Difference in signal (pA)4	GABA (μM)5
1	74	35	25	13
2	10	5	6	5

¹Number corresponds to signal trace number in Figure 7A. ²From Figure 7E, the IH₂O₂(E) value, i.e., the local Glu signal is measured. ³Then the local Glu concentration is known from Figure 8A. ⁴The I_GABA value is the difference between the IH₂O₂ values obtained from the two microbiosensors. ⁵Now, knowing the Glu concentration, which is the x-coordinate in Figure 8B and the I_GABA value, which is the y-coordinate in Figure 8B, one can find the GABA concentration for the two points.