Fig. 4.

Pie charts (A), representative traces (B and C, left), and the proposed neuronal circuits (B and C, right) in neurons in which perfusion with BIC did not affect the firing rate (N = 18) of DMV neurons. A: perfusion with KYN in the presence of BIC decreased the firing rate of DMV neurons (N = 5). B: the decrease in the firing rate in response to KYN was likely due to KYN-mediated inhibition of a tonic glutamatergic input onto DMV neurons. C: perfusion with KYN in the presence of BIC increased the firing rate of DMV neurons (N = 6), suggesting the presence of tonic glutamatergic synapses impinging onto non-GABAergic neurons.