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Control of Breathing & Airway Defense Seminar Series - Shared screen with gallery view
Kate Casey-Sawicki
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Kate Casey-Sawicki
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Christopher Del Negro
What is the fluorescent dye in Nick Bush’s experiment?
Nathan Baertsch
DiI is coating the recording probe to show location
Christopher Del Negro
But what was the rhythmic signal in the experiment?
Nathan Baertsch
Those experiments were done in vivo, and he records diaphragm emg and air flow which is then coordinated with the neuropixel recording
Jeehaeh Do
How do you know you’re not activating Chat+ upper airway motor neurons from the nucleus ambiguous directly?
Kevin Yackle
Given the anatomy, how is it possible to activate PiCo but not neighboring structures (like the nucleus ambiguus) when Chat-are is crossed with LSL-ChR2?
Kevin Yackle
Nathan Baertsch
The stimulations are not specific to any subpopulation of cholinergic neurons.
Alyssa Huff
Jeehaeh, This is a great question. We are working on experimental models to specifically target pico (vglut2+chat neurons). However when we repeat these same experiments targeting Vglut2 neurons at PiCo we get the same response as the chat experiments.
jack feldman
Alyssa: same problem. VGlut2 are widespread.
Eric Herlenius
Eszter Kish
Are the neonatal mice/human baby vocalizing at any of these points?
Nathan Baertsch
Eszter - this is a great question. We never made audio recordings in the newborns, but it could certainly be the case that they are vocalizing
Eszter Kish
How are these single units characterized as single units?
Paul McCulloch
Does the non-coordination of PiCo and PreBotC circuits early after birth in mice have any relation to SIDS in human infants?
Nathan Baertsch
The units undergo automated spike sorting
Nathan Baertsch
Paul - This is an intriguing idea. We don't know, but maybe we will have Nino address this at the end.
Alyssa Huff
Jack, Yes you are right this is not the perfect experiment and we are working on a more specific experiment. However the swallow response is location specific. If we stimulate vglut2 neurons at prebotC a swallow is not triggered whereas inspiration is.
jack feldman
How is the phenotype of neurons determined in vivo.
Jeehaeh Do
given that these neurons display bursting activity, is it possible you’re separating units into their bursting and tonic mode (and therefore separating their activity tuning)?
jack feldman
With all due respect to your UW colleague Al Berger, he played no role in the preBötC story.
Nathan Baertsch
Jack - they are optotagged with very short light pulses and neurons that respond within a short latency are considered "tagged"
Thomas Dick
I think Nino said Ellenberger and it sounded like Al Berger - As a former colleague - he preferred to be called Albert Berger - I venture to say you miss heard - we can check the recording
jack feldman
What is the criteria to distinguish direct optical stimulation from secondary stimulus, i.e., downstream from optoactivated neurons.
Christopher Del Negro
The refractory period is probably a lot shorter than 2 sec in vivo at physiological temperature
Nathan Baertsch
Jack- the latency from the light onset to the evoke action potential is used to distinguish direct excitation vs neurons excited synaptically.
Nathan Baertsch
Chris - yes I would agree this is likely. Also there is more feedback inhibition involved in vivo, which should reduce the refractory period
jack feldman
While our 1991 SCIENCE paper is the first formal publication of preBötC, Jeff and I presented our hypothesis a year earlier J. L. Feldman, C. A. Connelly, H. H. Ellenberger, J.C. Smith, Bur.]. Neurosci. Supple 3, 171 (1990).
dan mulkey
Any idea what channels mediate post-burst refractoriness in Dbx1 neurons (KCNQ?) and might these be directly subject to modulation by inhibitory signaling (as opposed to inhibitory signaling only working by limiting bursting)?
jack feldman
Nathan: Of course, there will be a delay between direct and secondary activation. My question is what criteria did you use, i.e., what delays were used to sort the neurons?
Christopher Del Negro
Dan — Na/K pump current, K-ATP current, and Na+ dependent K+ current. I think KCNQ is probably involved too as we recently published (first author Ann Revill)
dan mulkey
thanks Christopher!
Nathan Baertsch
Dan- There are many candidates that could mediate the intrinsic refractory properties. I did try a few experiments with a KCNQ antagonist, but the results weren't clear. The problem is that if you affect the burst, you also affect the refractory period, so interpretation is not straight forward.
Nathan Baertsch
Jack- I don't know the exact value Nick Bush used as his criteria. Nick?
dan mulkey
Thanks Nathan!
Alfredo Garcia
@Christopher and Nathan: So what I am hearing the refractory period is sensitive the [K+]o. Did either of you look at relationship between [K+]o and refractory period?
Nick Burgraff
Stay tuned for that data Fred! doing those recordings now
Christopher Del Negro
@Alfredo: We showed the refractory period was sensitive to [Ca2+]o, but did not test [K+]o dependence
Kaiwen Kam
Is it known whether NALCN, one of the effector targets of SP signaling, is differentially expressed in excitatory and inhibitory preBotC neurons?
Nathan Baertsch
Kaiwen - I'm not sure the definitive experiments have been done, but NK1 seems to be preferentially expressed on excitatory neurons.
Christopher Del Negro
NALCN (gene) expression is equivalent in Dbx1+ and non-Dbx1 neurons in preBotC (Hayes et al Sci Rep, 2017) RNA Seq study
Nathan Baertsch
Chis- Are you sure all glutamatergic preBotC neurons are derived from precursors expressing Dbx1 at E9.5? I think it is only a subset
Christopher Del Negro
What does Neuropixel record? What is the signal?
Nick Burgraff
Neuropixel records the spike activity
Nathan Baertsch
Neuropixel is a fancy multielectrode array which records extracellular activity
Donald Bolser
This is multi-unit activity?
Christopher Del Negro
Thanks @Nathan
Alicia Vose
alyssa Have you done any tracing between PICO and NTS to consider the incoming afferent information that modulates the swallow and is necessary for swallow initiation? Perhaps PICO is more of a hub receiving info from upper airway, lungs, diaphragm and info from prebotc to time swallowing with the optimal respiratory cycle (post-i/expiration)?
Nathan Baertsch
Don - if you are referring to the work in this PNAS study, yes it is integrated multiunit actiivty
Donald Bolser
ok thanks
Cleyton Sobrinho
all these neurons from the extend column has the same phenotype than the center core?
Donald Bolser
The overexcited state is a lot like what happens to insp amplitude during repetitive coughing
Christopher Del Negro
@Cleyton, there are Dbx1-derived neurons throughout th VRG but whether they have the same membrane properties outside preBötC is not known. My group has characterized Dbx1 neurons but only in preBötC
Cleyton Sobrinho
thanks @Christopher
Nathan Baertsch
Hi Cleyton - this is a good question! The answer is not straight forward, since even within the prebotC there are many different phenotypes that are not easily "grouped". This heterogeneity likely all applies to the more rostral neurons
Mia Kelly
Are there some respiratory-related behaviors that may benefit from some level of irregularity? / like coughing or particularly expressive vocalizations?
Cleyton Sobrinho
Thank you @Nathan
Nathan Baertsch
Mia - excellent question. Yes irregularity can be an important feature. I would speculate and say that this is because when the network is irregular, it is a sign that it is in a flexible state. And this flexibility is important for its function
Nathan Baertsch
Of course this must be balanced. Too much irregularity is also bad.
Bill Milsom
Does this imply that irregularity is indicative of ability to respond quickly to inpouts - similar to heart rate variability?
Gordon Mitchell
Very interesting hypothesis about opioid actions stabilizing or destabilizing depending on initial conditions. Is there evidence that opiates are released only at high levels of neuronal activity like some other peptides?
Nathan Baertsch
Bill - Yes, this is a great example
Alyssa Huff
Alicia, We have not done any tracing experiments yet, however with the addition of our new post doc out of Brazil Luiz Oliveira, new studies are in the works to look at excitatory and inhibitory connections from dorsal and ventral swallow/breathing related areas to PiCo we are beginning to understand the incoming afferent information as well as ongoing information about state affect the swallow pattern generator within the NTS and the iRt!
Prof. Dr. Gustavo Zubieta-Calleja
Excellent talk, Nino, as usual! The respiratory pacemaker is very complex with multiple security backup systems, as I understood. Hypoventilation is an issue in some Chronic Mountain Sickness patients. I published a paper that considered hypoventilation in CMS an energy saving mechanism due to pulmonary insufficiency in many diseases in the chronic hypoxia environment. Is there a possible Pre-Botzinger and Pico center interaction explanation for hypoventilation in a hypoxic environment?
Michael Matott
Does the overstimulation instability lead to a post-stimulation depression or do the areas recover stability fairly quickly?
Jonathan Rubin
I’m not sure stochastic is the right word. Chaotic deterministic dynamics can give the same result.
Alicia Vose
Alyssa - amazing work, so looking forward to learning more from your experiments!
Nathan Baertsch
Gordon - opioids can sometimes be given to treat tachypnea during panic attacks. Of course there is a lot going on in that context, but based on our data, it's easy to speculate that the opioids are helpful in pushing the respiratory network towards its stable state
Nick Burgraff
Gordon- I don't know, we'd have to look at the previous work. The conceptual ideas with the endorphins just focused on the "over"-excited state
Gordon Mitchell
Thanks Nathan was curious if endogenous opiate release was during high states of agitation, like Iverson’s demonstration of peptide release from raphe neurons?
dan mulkey
since many transmitters share common downstream signaling pathways it seems like convergence of these pathways should prevent hyperexcitability but that’s not what you see. Any idea why convergence does not prevent onset of a hyperexcitable/unstable state?
Alyssa Huff
Alicia, Thank You I appreciate that greatly!
Nathan Baertsch
Gordon - this is our working hypothesis. But why the respiratory network expresses MOR and how endogenous opioid signaling affects the system are still not well understood
Gordon Mitchell
Thanks Nathan and Nick
Gregory Funk
Thanks Nathan, thanks Nick!
Nick Burgraff
Interesting idea Dan. Perhaps some irregularity from over-excitation is from going beyond the limits of the convergence and other instances could be from lack of proper compensation
Donald Bolser
Great talk Nino!
Paloma Graziele Bittencourt
Really nice talk! I loved! I learned a lot!!!
Teresa Pitts
Great job Nino and the whole team!!
Eric Herlenius
Superbe Nino! Great talk and YES Every Breath is a new breath!Neurons, neuronal networks and circuits are crucial as well as sexy, but remember modulation by the mother astrocytes. Coupled oscillators .Apnea, Sighs, and Inspiratory modulation, (e.g Forsberg Elife 2016, 2017).More dynamic inspiration!
Luciane Gargaglioni
Amazing talk Nino! Thank you!
Donald Bolser
And thanks for the great responses to the questions Nick/Alyssa/Nathan
Donatella Mutolo
Thanks Nino! Great talk!
Jonathan Rubin
Great talk!! One more comment on stochastic: calling this stochastic de-emphasizes the many important dynamic effects of excitation, inhibition, and ion currents.
Nick Burgraff
THANK YOU for the wonderful questions. Amazingly helpful to all of the projects
Sofia Lopes Basílio da Silva Matos
Brilliant work! Thank you for the talk!
Jaime Eugenin
Thanks Nino for an excellent and motivating talk!
Eric Herlenius
SUPC ( Sudden Unexpected Collapse) Life-threatening events that occur during the first 7 postnatal life, some 4% of SIDS. Are mainly occurring during the first postnatal hours and associated with hours potsnatal hours and airway obstruction but, as SIDS a lot of ? remain- Pernatal fr. Inability to autorescitatec, respond to CO2 during first hours and during Inflammation induced alteration of homeostasis (eg PGE2). Coordination vocalization Inspitaion
Christopher Del Negro
Na/K pump is big. Also K-ATP current, Na-dependent K+ current, and maybe some KCNQ channels too
Mia Kelly
So interesting! Curious as to whether if there is a window on the curve most susceptible for plasticity inducing interventions :) Thanks for a great talk!
Eric Herlenius
Stochastic LAGOM excitation! Amazing Nino!
Consuelo Morgado-Valle
Thanks Nino. Great talk!