NEUR-MS20

Biological Rhythms and Motor Control

Thursday, June 17 at 11:30am (PDT)
Thursday, June 17 at 07:30pm (BST)
Friday, June 18 03:30am (KST)

SMB2021 Follow Thursday (Friday) during the "MS20" time block.

Note: this minisymposia has multiple sessions. The second session is MS19-NEUR (click here).

Yangyang Wang (University of Iowa, USA), Peter Thomas (Case Western Reserve University, USA)

Description:

The brain is strongly coupled to the body. Within the mathematical neuroscience community, there is growing appreciation that the analysis of neural circuits involved in motor control is inseparable from the analysis of the motor system that coevolved with, and is the raison d'etre for the brain. This double minisymposium will showcase efforts by applied mathematicians, typically in collaboration with experimental biologists, to understand the dynamics of rhythmic motor systems including respiration, swallowing, and locomotion, and to describe how phenomena such as robustness and homeostasis arise from rhythmic brain-body interactions. The first of two sessions will address control of respiratory rhythms in vertebrates and ingestive/digestive rhythms in invertebrates. The second session will address modeling of locomotory control systems, as well as the notion of homeostasis for general limit cycle systems.

Jon Rubin

(University of Pittsburgh, USA)

"Combining rhythm generation and pattern formation in a core respiratory neural circuit"

Although respiration seems simple on the surface (breathe in, breathe out, repeat!), looks can be deceiving. In this talk, I will (briefly) comment on two of the topics under active debate in the theory of the neural generation of respiratory rhythms. First, I will consider the issue of how rhythmic activity in the inspiratory core (in the famous pre-Botzinger complex of the mammalian brain stem) can succeed or fail to recruit widespread neural activation and motor output. This work, with Ryan Phillips, is done in the setting of Hodgkin-Huxley type neural models with synaptic coupling that also takes into account dynamics of certain relevant ion concentrations. Second, I will consider what happens when this rhythmic activity is embedded in the full neural circuit for respiration. This part of the talk will be based on work with Jeff Smith done in the simpler setting of coupled relaxation oscillators.

Casey Diekman

(New Jersey Institute of Technology, USA)

"Oxygen handling and parameter space interrogation in a minimalist closed-loop model of the respiratory oscillator"

Silent Hypoxemia, or happy hypoxemia is a puzzling phenomenon in which patients who have contracted COVID-19 exhibit very low oxygen saturations (SaO2 < 80%) yet experience no discomfort in breathing, or dyspnea. The mechanism by which this blunted response to hypoxia occurs is unknown. Our group has previously shown that a computational model (Diekman et al, 2017, J. Neurophys.) of the respiratory neural network can be used to test hypotheses focused on changes in chemosensory inputs to the central pattern generator (CPG). We hypothesize that altered chemosensory function at the level of the carotid bodies and/or the nucleus tractus solitarii are responsible for this blunted response to hypoxia. In this talk, we will use our model to explore this hypothesis by altering the properties of the gain function representing oxygen sensing inputs to the CPG. (Joint work with Christopher G. Wilson, Loma Linda University, and Peter J. Thomas, Case Western Reserve University.)

Todd Young

(Ohio University, USA)

"An Altered Van der Pol Oscillator and Stomatogastric Ganglion"

In the Stomatogastric Ganglion or Pyloric Network of Lobsters the LP neuron bursts 1:1 with a pacemaker group (PD) in the intact network. However, isolated LP neurons cycle much more slowly than the pacemaker group. How is the LP neuron able to adjust its firing rate to match the fast pacemaker? We propose that an alteration of a slow conductance is sufficient to explain this phenomenon and we illustrate the principal in an altered van der Pol system.

Yaroslav Molkov

(Georgia State University, USA)

"Control of steering in quadrupedal locomotion"

Traditionally, the studies of locomotor control in mammalian quadrupeds focus on spinal neural circuit organization that underlies varying patterns of limb movements (gaits) depending on the locomotor speed and other conditions. This intricate circuit includes neural rhythm generators that provide alternating flexion and extension phases for each limb, network interconnections between the generators providing proper interlimb coordination, descending control signals as well as proprioceptive feedback from the limbs. In the related experiments, the animal movements are usually restricted to walking or running along a straight path on a treadmill or over ground. Besides, to isolate particular functional components, the animals are often suspended or partly fixed. These restrictions make the balance control mechanisms irrelevant. However, during such complex maneuvers as turning, the timing of limb lifting and landing as well as limb positioning have to be tightly coordinated with the position of the center of mass to prevent the animal from falling. In addition, during turning movements quadrupedal mammals actively involve head/shoulder turning and body bending which further adds to the complexity of the control system. In this talk, we will use the experimental data on freely moving mice to develop a simple mathematical model of quadrupedal locomotion that includes a balance control system interacting with the locomotor pattern generating circuits. We show that the balance control is involved not only in complex maneuvers but also operates during straight-line locomotion. We argue that body bending is a mechanism involved in the appropriate limb positioning which is an integral part of the balance control system and as such is necessary for efficient turning. (Joint work with Ilya Rybak, Drexel University.)

Hosted by SMB2021 Follow

Virtual conference of the Society for Mathematical Biology, 2021.