A novel population of long-range inhibitory neurons

The hippocampus, a brain region important for spatial navigation and episodic memory, benefits from a rich diversity of neuronal cell-types. Recent work suggests fundamental gaps in our knowledge of these basic building blocks (i.e., neuronal types) in the hippocampal circuit, despite extensive prior examination. Through the use of an intersectional genetic viral vector approach, we report a novel hippocampal neuronal population, which has not previously been characterized, and which we refer to as LINCs. LINCs are GABAergic, but, in addition to broadly targeting local CA1 cells, also have long-range axons. LINCs are thus both interneurons and projection neurons. We demonstrate that LINCs, despite being relatively few in number, can have a strong influence on both hippocampal and extrahippocampal network synchrony and function. Identification and characterization of this novel cell population advances our basic understanding of both hippocampal circuitry and neuronal diversity.