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Respiratory rhythm entrainment by somatic afferent stimulation
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|Title: ||Respiratory rhythm entrainment by somatic afferent stimulation|
|Authors: ||Potts, Jeffrey T.|
Rybak, Ilya A.
Paton, Julian F. R.
|Keywords: ||Respiratory Control;Somatosensory Input;Pontomedullary Respiratory Network;Entrainment;Sensory-Motor Integration;Locomotion|
|Issue Date: ||23-Feb-2005|
|Publisher: ||Society for Neuroscience|
|Citation: ||Journal of Neuroscience, 25(8): pp. 1965-1978.|
|Abstract: ||Respiratory and locomotor patterns are coupled during locomotion. The objectives of this study were to (1) demonstrate that respiratory
rhythms are entrained by sensory input from somatic afferents, (2) establish whether the parabrachial nucleus mediates entrainment, (3)
examine responses of single respiratory neurons in the ventral respiratory group (VRG) to somatic afferent stimulation, and (4) use a computational
model of the pontomedullary respiratory network (Rybak et al., 2004a,b) to suggest neuronal mechanisms for entrainment.
We used an in situ preparation in young rats that retained pontomedullary respiratory circuits and spinal pathways transmitting
somatosensory input. We demonstrate that rhythmic stimulation of somatic afferents entrains respiratory rhythm on a 1:1 basis (1:1),
increasing breathing frequency up to 1.4 –2.2 times greater than spontaneous frequency. Stable entrainment occurred only when
stimuli were delivered during expiration. Reversible blockade of the lateral parabrachial nucleus eliminated entrainment. Somatic
afferent stimulation produced significant increases in the firing rate of augmenting expiratory (E2) neurons but shortened the firing
duration of postinspiratory (post-I) neurons.Acomputational model reproduced 1:1 entrainment and other experimental findings based
on the assumption that the somatic afferents initiate early onset of inspiration via activation of medullary E2 neurons. The model also
predicted that afferent stimulation evoked transient hyperpolarization of ramp-inspiratory (ramp-I) neurons. This was confirmed
experimentally by intracellular recording from ramp-I neurons. Our experimental and modeling results demonstrate that an entrainment
pathway from somatic afferents to the VRG via the lateral parabrachial nucleus causes resetting of respiratory rhythm through
excitation of E2 and consequent inhibition of post-I neurons.|
|Appears in Collections:||Faculty Research and Publications (Biomed Eng)|
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