scholarly journals Role of synaptic inhibition in turtle respiratory rhythm generation

2002 ◽  
Vol 544 (1) ◽  
pp. 253-265 ◽  
Author(s):  
Stephen M. Johnson ◽  
Julia E. R. Wilkerson ◽  
Michael R. Wenninger ◽  
Daniel R. Henderson ◽  
Gordon S. Mitchell
Keyword(s):  
Respiratory Rhythm ◽  
Synaptic Inhibition ◽  
Rhythm Generation ◽  
Respiratory Rhythm Generation

Are pacemaker properties required for respiratory rhythm generation in adult turtle brain stems in vitro?

2007 ◽  
Vol 293 (2) ◽  
pp. R901-R910 ◽  
Author(s):  
Stephen M. Johnson ◽  
Liana M. Wiegel ◽  
David J. Majewski
Keyword(s):  
Channel Blocker ◽  
Respiratory Rhythm ◽  
Cation Channels ◽  
Neuron Activity ◽  
Synaptic Inhibition ◽  
Dependent Manner ◽  
Rhythm Generation ◽  
Burst Frequency ◽  
Respiratory Rhythm Generation

The role of pacemaker properties in vertebrate respiratory rhythm generation is not well understood. To address this question from a comparative perspective, brain stems from adult turtles were isolated in vitro, and respiratory motor bursts were recorded on hypoglossal (XII) nerve rootlets. The goal was to test whether burst frequency could be altered by conditions known to alter respiratory pacemaker neuron activity in mammals (e.g., increased bath KCl or blockade of specific inward currents). While bathed in artificial cerebrospinal fluid (aCSF), respiratory burst frequency was not correlated with changes in bath KCl (0.5–10.0 mM). Riluzole (50 μM; persistent Na+ channel blocker) increased burst frequency by 31 ± 5% ( P < 0.05) and decreased burst amplitude by 42 ± 4% ( P < 0.05). In contrast, flufenamic acid (FFA, 20–500 μM; Ca2+-activated cation channel blocker) reduced and abolished burst frequency in a dose- and time-dependent manner ( P < 0.05). During synaptic inhibition blockade with bicuculline (50 μM; GABAA channel blocker) and strychnine (50 μM; glycine receptor blocker), rhythmic motor activity persisted, and burst frequency was directly correlated with extracellular KCl (0.5–10.0 mM; P = 0.005). During synaptic inhibition blockade, riluzole (50 μM) did not alter burst frequency, whereas FFA (100 μM) abolished burst frequency ( P < 0.05). These data are most consistent with the hypothesis that turtle respiratory rhythm generation requires Ca2+-activated cation channels but not pacemaker neurons, which thereby favors the group-pacemaker model. During synaptic inhibition blockade, however, the rhythm generator appears to be transformed into a pacemaker-driven network that requires Ca2+-activated cation channels.

Isolation of the Kernel for Respiratory Rhythm Generation in a Novel Preparation: The Pre-Bötzinger Complex “Island”

2001 ◽  
Vol 85 (4) ◽  
pp. 1772-1776 ◽  
Author(s):  
Shereé M. Johnson ◽  
Naohiro Koshiya ◽  
Jeffrey C. Smith
Keyword(s):  
Respiratory Rhythm ◽  
Fluorescent Imaging ◽  
Extracellular Potassium ◽  
Synaptic Inhibition ◽  
Rhythm Generation ◽  
Population Activity ◽  
Thin Slices ◽  
Bötzinger Complex ◽  
Population Burst ◽  
Respiratory Rhythm Generation

The pre-Bötzinger complex (pre-BötC), a bilaterally distributed network of rhythmogenic neurons within the ventrolateral medulla, has been proposed to be the critical locus for respiratory rhythm generation in mammals. To date, thin transverse medullary slice preparations that capture the pre-BötC have served as the optimal experimental model to study the region's inherent cellular and network properties. We have reduced the thin slices to isolated pre-BötC “islands” to further establish whether the pre-BötC has intrinsic rhythmicity and is the kernel for rhythmogenesis in the slice. We recorded neuron population activity locally in the pre-BötC with macroelectrodes and fluorescent imaging of Ca2+ activities with Calcium Green-1AM dye before and after excising the island. The isolated island remained rhythmically active with a population burst profile similar to the inspiratory burst in the slice. Rhythmic population activity persisted in islands after block of GABAAergic and glycinergic synaptic inhibition. The loci of pre-BötC Ca2+ activity imaged in thin slices and islands were similar, and imaged pre-BötC neurons exhibited synchronized flashing after blocking synaptic inhibition. Population burst frequency increased monotonically as extracellular potassium concentration was elevated, consistent with mathematical models consisting entirely of an excitatory network of synaptically coupled pacemaker neurons with heterogeneous, voltage-dependent bursting properties. Our results provide further evidence for a rhythmogenic kernel in the pre-BötC in vitro and demonstrate that the islands are ideal preparations for studying the kernel's intrinsic properties.

scholarly journals Role of persistent sodium current in mouse preBötzinger Complex neurons and respiratory rhythm generation

2007 ◽  
Vol 580 (2) ◽  
pp. 485-496 ◽  
Author(s):  
Ryland W. Pace ◽  
Devin D. Mackay ◽  
Jack L. Feldman ◽  
Christopher A. Del Negro
Keyword(s):  
Sodium Current ◽  
Respiratory Rhythm ◽  
Persistent Sodium Current ◽  
Rhythm Generation ◽  
Respiratory Rhythm Generation ◽  
Prebotzinger Complex ◽  
Prebötzinger Complex

Author response for "Key role of 5‐HT 1A receptors in the modulation of the neuronal network underlying the respiratory rhythm generation in lampreys"

2020 ◽  
Author(s):  
Elenia Cinelli ◽  
Donatella Mutolo ◽  
Ludovica Iovino ◽  
Tito Pantaleo ◽  
Fulvia Bongianni
Keyword(s):  
Neuronal Network ◽  
Respiratory Rhythm ◽  
Author Response ◽  
Rhythm Generation ◽  
Respiratory Rhythm Generation
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