(a) Example traces demonstrating blockade of current injection-evoked action potentials by DEAC454-GABA (left) and PEG-DEAC450-GABA (right) uncaging with 470 and 365 nm light in hippocampal CA1 neurons. Black: no uncaging; blue: 470 nm, violet: 365 nm. (b) Summarized results comparing the power threshold for action potential blockade using blue or near-UV light for DEAC454-GABA (n = 8 cells) and PEG-DEAC450-GABA (n = 3 cells). For all cells, current-injections were paired with increasing energy of light. The light energy threshold to block the action potential was averaged across cells. Recordings were made in the presence of AMPA (CNQX, 10 μM), NMDA (DL-AP5, 100 μM) and GABA-B receptor (CGP-55845, 3 μM) and mGluR (JNJ-16259685, 1 μM; MPEP, 3 μM; LY341495, 30 nM) antagonists.