Figure 3.

DAF phototoxicity is selective to interneurons with LTS firing pattern. Layer 5 neurons were recorded in slices pre-incubated in DAF-2DA (2 μM, 10 min). (A) The left panel displays typical firing pattern of a pyramidal RS neuron in response to depolarizing current pulse. The resting potential is marked to the left. On the right—the recorded trace before opening the fluorescent shutter (arrow), during illumination (dotted line) and afterwards. A hyperpolarizing current pulse monitored the membrane resistance, and examples from time points “a” and “b” are displayed above. (B) Example traces of the response of a FS-type interneuron to light. Details as in (A). (C) Example traces of the response of a LTS-type interneuron to light. Note on the right panel the appearance of instability of the membrane potential and a reduction of membrane resistance shortly after opening the shutter (closed arrow), and loss of the membrane potential shortly before the end of illumination (open arrow). (D) Images of the neuron in (C). On the left is an IR/DIC image of the patched neuron. An arrow points to the tip of the recording pipette. The middle image shows the same field under fluorescent light, showing faint staining in the recorded neuron. On the right is a combined image.