Pre-Bötzinger Complex Inspiratory Neurons and Rhythm Generation

Commissural interneurons in rhythm generation and intersegmental coupling in the lamprey spinal cord. To test the necessity of spinal commissural interneurons in the generation of the swim rhythm in lamprey, longitudinal midline cuts of the isolated spinal cord preparation were made. Fictive swimming was then induced by bath perfusion with an excitatory amino acid while recording ventral root activity. When the spinal cord preparation was cut completely along the midline into two lateral hemicords, the rhythmic activity of fictive swimming was lost, usually replaced with continuous ventral root spiking. The loss of the fictive swim rhythm was not due to nonspecific damage produced by the cut because rhythmic activity was present in split regions of spinal cord when the split region was still attached to intact cord. The quality of this persistent rhythmic activity, quantified with an autocorrelation method, declined with the distance of the split spinal segment from the remaining intact spinal cord. The deterioration of the rhythm was characterized by a lengthening of burst durations and a shortening of the interburst silent phases. This pattern of deterioration suggests a loss of rhythmic inhibitory inputs. The same pattern of rhythm deterioration was seen in preparations with the rostral end of the spinal cord cut compared with those with the caudal end cut. The results of this study indicate that commissural interneurons are necessary for the generation of the swimming rhythm in the lamprey spinal cord, and the characteristic loss of the silent interburst phases of the swimming rhythm is consistent with a loss of inhibitory commissural interneurons. The results also suggest that both descending and ascending commissural interneurons are important in the generation of the swimming rhythm. The swim rhythm that persists in the split cord while still attached to an intact portion of spinal cord is thus imposed by interneurons projecting from the intact region of cord into the split region. These projections are functionally short because rhythmic activity was lost within approximately five spinal segments from the intact region of spinal cord.

Physiological Properties of Late Inspiratory Neurons and Their Possible Involvement in Inspiratory Off-Switching in Cats

Journal of Neurophysiology ◽

10.1152/jn.00470.2001 ◽

2002 ◽

Vol 87 (2) ◽

pp. 1057-1067 ◽

Cited By ~ 29

Author(s):

Akira Haji ◽

Mari Okazaki ◽

Hiromi Yamazaki ◽

Ryuji Takeda

Keyword(s):

Nmda Receptors ◽

Gaba Release ◽

Membrane Depolarization ◽

Inhibitory Neurons ◽

Acid Decarboxylase ◽

Postsynaptic Potentials ◽

Inspiratory Neurons ◽

Small Constant ◽

Physiological Properties ◽

Decerebrate Cats

To assess the functional significance of late inspiratory (late-I) neurons in inspiratory off-switching (IOS), membrane potential and discharge properties were examined in vagotomized, decerebrate cats. During spontaneous IOS, late-I neurons displayed large membrane depolarization and associated discharge of action potentials that started in late inspiration, peaked at the end of inspiration, and ended during postinspiration. Depolarization was decreased by iontophoresis of dizocilpine and eliminated by tetrodotoxin. Stimulation of the vagus nerve or the nucleus parabrachialis medialis (NPBM) also evoked depolarization of late-I neurons and IOS. Waves of spontaneous chloride-dependent inhibitory postsynaptic potentials (IPSPs) preceded membrane depolarization during early inspiration and followed during postinspiration and stage 2 expiration of the respiratory cycle. Iontophoresed bicuculline depressed the IPSPs. Intravenous dizocilpine caused a greatly prolonged inspiratory discharge of the phrenic nerve (apneusis) and suppressed late-inspiratory depolarization as well as early-inspiratory IPSPs, resulting in a small constant depolarization throughout the apneusis. NPBM or vagal stimulation after dizocilpine produced small, stimulus-locked excitatory postsynaptic potentials (EPSPs) in late-I neurons. Neurobiotin-labeled late-I neurons revealed immunoreactivity for glutamic acid decarboxylase as well as N-methyl-d-aspartate (NMDA) receptors. These results suggest that late-I neurons are GABAergic inhibitory neurons, while the effects of bicuculline and dizocilpine indicate that they receive periodic waves of GABAergic IPSPs and glutamatergic EPSPs. The data lead to the conclusion that late-I neurons play an important inhibitory role in IOS. NMDA receptors are assumed to augment and/or synchronize late-inspiratory depolarization and discharge of late-I neurons, leading to GABA release and consequently off-switching of bulbar inspiratory neurons and phrenic motoneurons.

Effect of individual spiking activity on rhythm generation of central pattern generators

Neurocomputing ◽

10.1016/j.neucom.2004.01.091 ◽

2004 ◽

Vol 58-60 ◽

pp. 535-540 ◽

Cited By ~ 15

Author(s):

Roberto Latorre ◽

Francisco de Borja Rodrı́guez ◽

Pablo Varona

Keyword(s):

Central Pattern Generators ◽

Rhythm Generation ◽

Pattern Generators ◽

Spiking Activity

Effects of contralateral superior laryngeal nerve stimulation on dorsal medullary inspiratory neurons

Brain Research ◽

10.1016/0006-8993(89)90127-3 ◽

1989 ◽

Vol 505 (1) ◽

pp. 149-152 ◽

Cited By ~ 4

Author(s):

David F. Donnelly ◽

Anthony L. Sica ◽

Morton I. Cohen ◽

Heng Zhang

Keyword(s):

Nerve Stimulation ◽

Superior Laryngeal Nerve ◽

Laryngeal Nerve ◽

Inspiratory Neurons

Localization of essential rhombomeres for respiratory rhythm generation in bullfrog tadpoles using a binary search algorithm: Rhombomere 7 is essential for the gill rhythm and suppresses lung bursts before metamorphosis

Developmental Neurobiology ◽

10.1002/dneu.22108 ◽

2013 ◽

Vol 73 (12) ◽

pp. 888-898 ◽

Cited By ~ 14

Author(s):

Maryana Duchcherer ◽

Mufaddal I. Baghdadwala ◽

Jenny Paramonov ◽

Richard J.A. Wilson

Keyword(s):

Search Algorithm ◽

Respiratory Rhythm ◽

Binary Search ◽

Rhythm Generation ◽

Binary Search Algorithm ◽

Respiratory Rhythm Generation