Figure 2.

Optical targeting of local inhibitory input to O–LM INs. (A) Representative traces of IPSCs evoked in O–LM INs by local glutamate uncaging on PYR/RAD INs (uIPSCs; superimposition of three consecutive traces with an individual trace shown as an inset) in control and after application of bicuculline. The right panel shows summary data of uIPSC peak amplitude before and after bicuculline application (n = 6). Horizontal bars below the traces indicate the duration of uncaging pulses. (B) The distribution histograms of uIPSC peak amplitude (left), rise time (middle), and decay time constant (right) from all cells (n = 5). (C) Neurolucida reconstruction of monosynaptically connected RAD and O–LM INs filled with biocytin, showing anatomical features (bipolar orientation, extensive axonal arborization in the O/A) of an interneuron innervating an O–LM cell. Soma and dendrites of the presynaptic RAD IN are shown in green, and its axonal arborization is shown in blue. Soma and dendrites of the postsynaptic O–LM IN are shown in dark blue and its axonal arborization is shown in red. (D) Responses of the presynaptic RAD IN to current pulses (top) and a plot of the interspike interval as a function of pulse duration at different levels of membrane depolarization (bottom) demonstrating the irregular firing pattern of the RAD IN innervating the O–LM cell.