Figure 1.

Multiple effects of SCN stimulation on identified sleep-promoting VLPO neurons. A, Schematic view of the acute AH/POA horizontal slice preparation. Insets, Sections (lines a–c) performed to prepare the horizontal slice (left inset) and a typical triangular-shaped neuron recorded in the VLPO (right inset). B, C, A typical VLPO neuron recorded in whole-cell configuration in the current-clamp mode displays a low-threshold spike at the end of a hyperpolarizing current step (B) and is transiently hyperpolarized and inhibited (C) by bath-applied NA. D–F, In voltage-clamp mode, SCN single-pulse stimulations (*; 200 μA) evoke NBQX (25 μm)-sensitive EPSCs (D), bicuculline (20 μm)-sensitive IPSCs (E), or a mixture of both (F). Traces in D–F are an average of 10 consecutive stimulations. G, Whereas an SCN single-pulse stimulation (200 μA; G1, *) evokes a unique PSC (dot in inset), train stimulations of increasing duration (G2, **; G3, ***) evoke, in addition to reliable PSCs after each single stimulation (G2, dots in inset), a long-lasting outward current (G2, G3, arrowheads). As evident when recording the same neuron in current-clamp mode, such a current subtended a long-lasting hyperpolarization (G3, inset). 3V, Third ventricle; opt, optic tract; ox, optic chiasm; Bic, bicuculline.