Laser ablation of Dbx1 neurons in the pre-Bötzinger complex stops inspiratory rhythm and impairs output in neonatal mice.
Bottom Line: To understand the neural origins of rhythmic behavior one must characterize the central pattern generator circuit and quantify the population size needed to sustain functionality.Breathing-related interneurons of the brainstem pre-Bötzinger complex (preBötC) that putatively comprise the core respiratory rhythm generator in mammals are derived from Dbx1-expressing precursors.These results demonstrate that a single canonical interneuron class generates respiratory rhythm and contributes in a premotor capacity, whereas these functions are normally attributed to discrete populations.
Affiliation: Department of Applied Science, The College of William and Mary, Williamsburg, United States.Show MeSH
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Mentions: Dbx1 neurons were detected and mapped within the preBötC, and then laser ablated individually, in sequence, while monitoring respiratory network functionality via XII motor nerve output. Experiments began with an ‘initialization phase’ that defined the domain for detection and ablation, which was bilateral. We used a Dbx1 Cre-driver line (Dbx1CreERT2) coupled with floxed reporter mice (Gt(ROSA)26Sorflox-stop-tdTomato) to locate Dbx1 neurons via fluorescence. Viewed in the transverse plane of slices that expose the preBötC at their surface (i.e., preBötC-surface slices), Dbx1 neurons form a bilaterally symmetrical V-shape starting dorsally at the border of the XII motor nuclei and continuing ventrolaterally to the preBötC (Figure 1A and Figure 1—figure supplement 1A). Dorsally, the preBötC adjoins the semi-compact division of the nucleus ambiguus (scNA); the ventral border of the preBötC is orthogonal to the dorsal boundary of the principal sub-nucleus of the inferior olive (IOPloop) (Ruangkittisakul et al., 2011, 2014). These spatial relationships visible in bright field or epifluorescence allow us to pinpoint the preBötC (Figure 1A). At the cellular level, identifying putative rhythmogenic neurons on the basis of fluorescent protein expression alone is acceptable because the overwhelming majority of Dbx1 preBötC neurons are inspiratory (e.g., Figure 1B) (Picardo et al., 2013).10.7554/eLife.03427.003Figure 1.Dbx1 preBötC neurons.
Affiliation: Department of Applied Science, The College of William and Mary, Williamsburg, United States.