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Laser ablation of Dbx1 neurons in the pre-Bötzinger complex stops inspiratory rhythm and impairs output in neonatal mice.

Wang X, Hayes JA, Revill AL, Song H, Kottick A, Vann NC, LaMar MD, Picardo MC, Akins VT, Funk GD, Del Negro CA - Elife (2014)

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.

View Article: PubMed Central - PubMed

Affiliation: Department of Applied Science, The College of William and Mary, Williamsburg, United States.

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Dbx1 preBötC neurons with premotor function.(A) Fluorescence and (B) bright field images of a slice preparation. Anatomical landmarks are illustrated including: XII, the hypoglossal motor nucleus; scNA, semi-compact division of the nucleus ambiguus; IOPloop, the ventral loop of the principal inferior olive, and the ventral surface of the preBötC. Scale bar is 100 µm and applies to A and B. A patch-recording pipette is visible, marking the inspiratory-modulated neuron detailed in C–E. A dotted circle indicates the tip of the pipette and cell body. (C and D) tdTomato expression, intracellular dialysis of Alexa 488, and merged image (C) from the inspiratory neuron shown with XII nerve output (D). Voltage and time calibration bars represent 20 mV and 1 s. Baseline membrane potential in the recorded neuron was −60 mV. (E) Antidromic activation of the Dbx1 inspiratory neuron from C and D. Action potentials were evoked by XII stimulation (left) and intracellular 5-ms supra-threshold current pulses (middle). When the antidromic XII stimulus was preceded immediately by a supra-threshold intracellular current pulse, the antidromic spike was occluded (collision test, right). Several sweeps, all from a −62 mV baseline membrane potential, are superimposed with vertical offset in each case. Voltage calibration is the same as panel D. Applied current (Iapp) calibration is shown. Time calibration bar for E is 25 ms.DOI:http://dx.doi.org/10.7554/eLife.03427.015
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fig7: Dbx1 preBötC neurons with premotor function.(A) Fluorescence and (B) bright field images of a slice preparation. Anatomical landmarks are illustrated including: XII, the hypoglossal motor nucleus; scNA, semi-compact division of the nucleus ambiguus; IOPloop, the ventral loop of the principal inferior olive, and the ventral surface of the preBötC. Scale bar is 100 µm and applies to A and B. A patch-recording pipette is visible, marking the inspiratory-modulated neuron detailed in C–E. A dotted circle indicates the tip of the pipette and cell body. (C and D) tdTomato expression, intracellular dialysis of Alexa 488, and merged image (C) from the inspiratory neuron shown with XII nerve output (D). Voltage and time calibration bars represent 20 mV and 1 s. Baseline membrane potential in the recorded neuron was −60 mV. (E) Antidromic activation of the Dbx1 inspiratory neuron from C and D. Action potentials were evoked by XII stimulation (left) and intracellular 5-ms supra-threshold current pulses (middle). When the antidromic XII stimulus was preceded immediately by a supra-threshold intracellular current pulse, the antidromic spike was occluded (collision test, right). Several sweeps, all from a −62 mV baseline membrane potential, are superimposed with vertical offset in each case. Voltage calibration is the same as panel D. Applied current (Iapp) calibration is shown. Time calibration bar for E is 25 ms.DOI:http://dx.doi.org/10.7554/eLife.03427.015

Mentions: Lower cell ablation tallies perturbed and stopped the rhythm in simulations, and the aggregate burst magnitude did not decline (Figure 6C,E, and Figure 6—figure supplement 1C, Supplementary file 1). Both disparities could be explained if a subset of the experimentally lesioned population consists of premotor—rather than rhythmogenic—interneurons. Thus, we tested whether Dbx1 preBötC neurons project to the XII motor nucleus. Of the eight Dbx1 neurons with inspiratory modulation (Figure 7A–D), two could be antidromically activated by stimulation within the XII nucleus. Figure 7 shows representative data from such a Dbx1 neuron whose XII-evoked antidromic spike was extinguished by collision with an orthodromic spike triggered by a somatic current pulse (Figure 7E). Most Dbx1 preBötC neurons are inspiratory and show commissural axons that cross the midline and innervate the contralateral preBötC (Figure 8A–C), as shown previously (Bouvier et al., 2010; Picardo et al., 2013). Here, we identify Dbx1 preBötC neurons that are also inspiratory modulated but send axons ipsilaterally toward the XII nucleus (Figure 8D–F and Figure 8—figure supplement 1), consistent with a role related to premotor transmission of inspiratory drive from preBötC to XII motoneurons.10.7554/eLife.03427.015Figure 7.Dbx1 preBötC neurons with premotor function.


Laser ablation of Dbx1 neurons in the pre-Bötzinger complex stops inspiratory rhythm and impairs output in neonatal mice.

Wang X, Hayes JA, Revill AL, Song H, Kottick A, Vann NC, LaMar MD, Picardo MC, Akins VT, Funk GD, Del Negro CA - Elife (2014)

Dbx1 preBötC neurons with premotor function.(A) Fluorescence and (B) bright field images of a slice preparation. Anatomical landmarks are illustrated including: XII, the hypoglossal motor nucleus; scNA, semi-compact division of the nucleus ambiguus; IOPloop, the ventral loop of the principal inferior olive, and the ventral surface of the preBötC. Scale bar is 100 µm and applies to A and B. A patch-recording pipette is visible, marking the inspiratory-modulated neuron detailed in C–E. A dotted circle indicates the tip of the pipette and cell body. (C and D) tdTomato expression, intracellular dialysis of Alexa 488, and merged image (C) from the inspiratory neuron shown with XII nerve output (D). Voltage and time calibration bars represent 20 mV and 1 s. Baseline membrane potential in the recorded neuron was −60 mV. (E) Antidromic activation of the Dbx1 inspiratory neuron from C and D. Action potentials were evoked by XII stimulation (left) and intracellular 5-ms supra-threshold current pulses (middle). When the antidromic XII stimulus was preceded immediately by a supra-threshold intracellular current pulse, the antidromic spike was occluded (collision test, right). Several sweeps, all from a −62 mV baseline membrane potential, are superimposed with vertical offset in each case. Voltage calibration is the same as panel D. Applied current (Iapp) calibration is shown. Time calibration bar for E is 25 ms.DOI:http://dx.doi.org/10.7554/eLife.03427.015
© Copyright Policy - open-access
Related In: Results  -  Collection

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fig7: Dbx1 preBötC neurons with premotor function.(A) Fluorescence and (B) bright field images of a slice preparation. Anatomical landmarks are illustrated including: XII, the hypoglossal motor nucleus; scNA, semi-compact division of the nucleus ambiguus; IOPloop, the ventral loop of the principal inferior olive, and the ventral surface of the preBötC. Scale bar is 100 µm and applies to A and B. A patch-recording pipette is visible, marking the inspiratory-modulated neuron detailed in C–E. A dotted circle indicates the tip of the pipette and cell body. (C and D) tdTomato expression, intracellular dialysis of Alexa 488, and merged image (C) from the inspiratory neuron shown with XII nerve output (D). Voltage and time calibration bars represent 20 mV and 1 s. Baseline membrane potential in the recorded neuron was −60 mV. (E) Antidromic activation of the Dbx1 inspiratory neuron from C and D. Action potentials were evoked by XII stimulation (left) and intracellular 5-ms supra-threshold current pulses (middle). When the antidromic XII stimulus was preceded immediately by a supra-threshold intracellular current pulse, the antidromic spike was occluded (collision test, right). Several sweeps, all from a −62 mV baseline membrane potential, are superimposed with vertical offset in each case. Voltage calibration is the same as panel D. Applied current (Iapp) calibration is shown. Time calibration bar for E is 25 ms.DOI:http://dx.doi.org/10.7554/eLife.03427.015
Mentions: Lower cell ablation tallies perturbed and stopped the rhythm in simulations, and the aggregate burst magnitude did not decline (Figure 6C,E, and Figure 6—figure supplement 1C, Supplementary file 1). Both disparities could be explained if a subset of the experimentally lesioned population consists of premotor—rather than rhythmogenic—interneurons. Thus, we tested whether Dbx1 preBötC neurons project to the XII motor nucleus. Of the eight Dbx1 neurons with inspiratory modulation (Figure 7A–D), two could be antidromically activated by stimulation within the XII nucleus. Figure 7 shows representative data from such a Dbx1 neuron whose XII-evoked antidromic spike was extinguished by collision with an orthodromic spike triggered by a somatic current pulse (Figure 7E). Most Dbx1 preBötC neurons are inspiratory and show commissural axons that cross the midline and innervate the contralateral preBötC (Figure 8A–C), as shown previously (Bouvier et al., 2010; Picardo et al., 2013). Here, we identify Dbx1 preBötC neurons that are also inspiratory modulated but send axons ipsilaterally toward the XII nucleus (Figure 8D–F and Figure 8—figure supplement 1), consistent with a role related to premotor transmission of inspiratory drive from preBötC to XII motoneurons.10.7554/eLife.03427.015Figure 7.Dbx1 preBötC neurons with premotor function.

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.

View Article: PubMed Central - PubMed

Affiliation: Department of Applied Science, The College of William and Mary, Williamsburg, United States.

Show MeSH
Related in: MedlinePlus