Figure 5.

Activity of CA1 long-range projecting interneurons during theta and ripple oscillations

(A) Most relevant long-range projecting interneuron types in CA1. For reference, the somatodendritic layout of a schematic pyramidal cell (PC, left) is included. ENK indicates an enkephalin expressing cell. Extrahippocampal projection target areas are indicated for some of the cell types: Sub, subiculum; RSC, retrosplenial cortex; MEC/LEC, medial/lateral entorhinal cortex; lat/med Sept., lateral/medial septum; ant. cing. Ctx, anterior cingular cortex.

(B–D) Properties of the interneuron classes displayed in (A), during theta oscillations (upper row) and ripples (lower row). The data are compiled from various studies. (a–g), with the following experimental conditions: (a) anesthetized rat⁶⁰; (b) anesthetized rat (for theta and ripple, two and three individual cells, respectively, reported)⁵⁷; (c) anesthetized rat, one cell reported¹⁶⁸; (d) freely moving rat,⁶⁴ one cell reported; (e) awake/head-fixed mouse,⁶⁵ (for ripples, three individual cells, termed “extrinsic interneurons” located in CA1 and CA3 radiatum, and hilus, reported); (f) freely moving rat⁵⁹ (for theta, during REM sleep [f1, green] and during movement [f2, yellow]; for ripples: value reflects activity recorded during slow-wave sleep; however, LFP was not independently monitored; it remains uncertain whether the ∼200 Hz activity actually reflects ripple-related activation of this cell type); (g) awake head-fixed mouse.²⁰ (B) Spike rates. (C) Preferred spike phases. Phase values are given with a full cycle of oscillations as a reference. (D) Modulation strength as in Figure 4D. The error bars shown represent the margins of error reported in the indicated studies.