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Monday, July 20 • 7:00pm - 8:00pm
P173: How energy constraints shape brain dynamics during hypoxia and epileptic seizures

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Shrey Dutta, James A Roberts

Google Meet link: https://meet.google.com/xxc-ifyr-fai
The brain consumes 20% of the body's energy, 10 times more than predicted by its mass, which makes it highly sensitive to metabolic disturbances [1]. Asphyxia and epileptic seizures disrupt energy and oxygen availability in the brain, leading to pathological activity in the electroencephalogram (EEG) [2-4]. Modelling the bidirectional relationship between brain activity and energy resources is crucial to understand brain disorders where metabolic disturbances are implicated. Most models of brain activity do not explicitly include metabolic variables and so are unable to address dynamical constraints on energy resources. Here, we explore the roles of energy demand and energy supply in Hodgkin-Huxley neurons augmented with the energy resource dynamics of Na+/K+ pumps [4]. Using a small-scale network of excitatory and inhibitory neurons, we show that during high energy demand and low energy supply (extreme hypoxia) the model simulates scale-free burst suppression with asymmetric longer-duration bursts (Figure 1)—similar to empirical EEG from infants recovering from hypoxia. During normal energy demand and low-to-moderate energy supply the model generates several types of epileptic seizures (Figure 1). We also show multiple mechanisms for seizure terminations depending on the magnitude of hypoxia. Seizure termination during low energy supply is due to depletion of local energy resources, while during moderate energy supply ion (Na+ & K+) imbalances terminate the seizure. This suggests that seizure termination due to lack of energy is a potential mechanism for postictal generalised EEG suppression. Our results unify burst suppression during hypoxia and epileptic seizures, and our modelling provides a general platform to study brain pathologies linked with metabolic disturbances.

References

[1] Raichle, M. E. (2006). The brain's dark energy. Science, 314(5803):1249–1250

[2] Roberts, J. A., Iyer, K. K., Finnigan, S., Vanhatalo, S., and Breakspear, M. (2014). Scale-free bursting in human cortex following hypoxia at birth. The Journal of neuroscience, 34(19):6557–6572

[3] Jirsa, V. K., Stacey, W. C., Quilichini, P. P., Ivanov, A. I., and Bernard, C. (2014). On the nature of seizure dynamics. Brain, 137(8):2210–2230

[4] Wei, Y., Ullah, G., Ingram, J., and Schiff, S. J. (2014). Oxygen and seizure dynamics: II.Computational modeling. Journal of neurophysiology, 112(2):213–223

Speakers
SD

Shrey Dutta

Student, Faculty of Medicine, QIMR Berghofer Medical Research Institute, University of Queensland



Monday July 20, 2020 7:00pm - 8:00pm CEST
Slot 08