Enhanced neuronal excitability in the CeLC neurons in brain slice of formalin-treated mice. CeLC neurons in slices from untreated control and formalin treated mice were tested 24 hours after inflammation by injection with 20 pA current steps. Example of CeLC neuron firing patterns of untreated control (A), and formalin-treated mice (B) in response to the depolarizing current steps. (C) Average data showing increased action potential frequency in the CeLC neurons in brain slices 24 hours after inflammatory insult compared to untreated control [Formalin (n = 18), Control (n = 30)].(D) Average rheobase current in CeLC neurons in brain slices [Control (n = 28), Formalin (18)]. Data presented as mean ± SEM, *p ≤ 0.05 vs. control, Student's t-test. Recordings were in Mg2+ free ACSF.