Figure 4

PV-positive and SOM-positive LHb neurons form physiologically distinct sub-classes. (A) Breeding scheme for generating PV and SOM-IRES-Cre::Ai9 mice. (B) Comparison of passive physiological properties between all groups. (C) Confocal micrograph depicting localization of PV-positive neurons within the LHb. (D) Initial action potential firing frequency versus current injection for both PV-positive (n = 18; N = 8 mice) and general population (n = 16; N = 5 mice) LHb neurons recorded in C57 mice. Data are mean ± SEM. (E) Schematic illustrating location of patched neurons within the habenular complex. (F) Example traces from PV-positive neurons upon current injection. (Fa): traces from a neuron in the medial LHb. Asterisk indicates a section from the recording displaying characteristic sub-threshold voltage oscillations. (Fb): traces from a neuron in the lateral LHb. Current steps: −50 pA and 50 pA; 1 s duration. (G) Comparison of passive properties between PV positive neurons in the lateral LHb (n = 11) and medial LHb (n = 8). Data are mean ± SEM. (H) Example reconstructions from two PV-positive neurons. (I) As for (D), for SOM-positive LHb neurons (n = 22; N = 3 mice). (J) As for (E), in for SOM-positive neurons. (K) Example traces from one neuron when held at −50 mV and −70 mV upon 1 s injection of 50 pA current. Zoom: comparison of the first induced action potential at each holding potential. (La) Inter-event interval (IEI) between the first and second action potential induced upon depolarising current injection (20–150 pA; 1 s) for neurons at different holding potentials (n = 11). (Lb) Comparison of amplitude of the first (‘early spike’) action potential induced upon depolarising current injection (20–150 pA; 1 s) for neurons at different holding potentials (n = 11). (Lc) Comparison of kinetics (rise time and half-width) of the first action potential induced upon depolarising current injection (20–150 pA; 1 s) for neurons at different holding potentials (n = 11). (M) Example reconstructions from a SOM-positive neuron within the superior sub-nucleus (top; n = 6), and from another SOM-positive neuron out with the superior sub-nucleus (bottom; n = 4).