A projection atlas of excitatory and inhibitory inputs to the preBötzinger Complex: substrates for multimodal breathing control

Abstract

Breathing is an essential motor behavior that emerges from the activity of rhythm-generating neurons in the preBotzinger Complex (preBotC). Although the properties of preBotC neurons are sufficient for rhythmogenesis, their activity is continually shaped by long-range inputs that convey homeostatic, emotional, volitional, and behavioral influences. Here, we provide a systematic survey of monosynaptic projections from excitatory (glutamatergic) and inhibitory (GABAergic) neurons across the mouse brain that target the preBotC. Using a dual recombinase-dependent retrograde tracing approach, we compile an atlas of afferent regions, highlighting the breadth of excitatory and inhibitory inputs that converge on this critical network. This atlas underscores the preBotC as a nexus where multimodal signals are integrated to regulate rhythm generation and patterning. Rather than a self-contained oscillator, the preBotC is a hub whose function is tuned by diverse long-range excitatory and inhibitory influences. By defining the anatomical substrates of this input, we lay a foundation for dissecting the functional roles of higher-order brain regions in shaping breathing across physiological, behavioral, and pathological contexts. SIGNIFICANCE STATEMENTBreathing is controlled by a small brainstem region called the preBotzinger Complex, which generates the rhythm for each breath. Many other brain areas influence this region, but the sources of these inputs--and whether they excite or inhibit breathing--have not been systematically mapped. Here, we present a detailed anatomical atlas identifying where excitatory and inhibitory signals to the preBotzinger Complex arise across the mouse brain. This resource provides a structural framework for understanding how breathing is shaped by sensory signals, behavior, and brain state.