Cecilia Diniz Behn

I am an active member of the AMS Math Biology Research Group.

Diniz Behn Research Group

My research group currently includes

From left to right: Kelsey Kalmbach, Nick Koprowicz, Cecilia Diniz Behn, Nora Stack, and Mollie Murray (not pictured: Kai Bartlette).

Recent graduates of my group are Jacqueline Simens (MS 2015), Sean Lopp (BS 2015), and Abigail Branch (BS 2015).

Current Research Projects

Multiple time scales in sleep-wake modeling

Sleep-wake behavior is produced by the interaction of many processes occurring on a range of spatial and temporal scales: individual neurons spiking on a millisecond time scale coordinate their activity to promote states of wake and sleep that are modulated by processes, such as the approximately 24-hour circadian drive, that act on time scales of days. Mathematical modeling provides a key tool for integrating anatomic and physiologic data across these scales to probe the dynamic interactions of these elements. Current and ongoing work in this area involves the application of reduction of dimension and fast-slow techniques to identify mechanisms of state transition; establishing numerical criteria to compare and contrast the existence and robustness of REM/non-REM cycling produced by different putative REM-generating network structures; and investigating interactions between sleep and circadian systems.

Glucose-insulin dynamics and tissue-specific insulin resistance

In recent years, my research program has increasingly addressed questions of whole-body metabolism. From a physiological perspective, the common role of the hypothalamus provides a unified substrate for sleep/circadian and metabolic investigation. However, my current research considers metabolism in contexts outside, as well as inside, the brain. My collaborators are pioneering novel experimental protocols involving multiple stable isotope tracers to provide less-invasive techniques to assess tissue-specific insulin resistance (IR) in at-risk adolescent populations. However, new mathematical tools are necessary for optimal mining and interpretation of these complex data sets, and current work focuses on meeting this need.

Orexin/hypocretin neurons and their role in stabilizing sleep-wake behavior

In normal sleep-wake behavior, the neuropeptide orexin (also known as hypocretin) helps to stabilize transitions between wake and sleep, and dysregulation of orexin is associated with the sleep disorder narcolepsy. Since the state instability that characterizes narcolepsy reflects an alteration of the network dynamics producing sleep-wake behavior, mathematical approaches aimed at understanding the stability of the network provide vital complementary techniques to traditional sleep research. In previous work I have developed higher-order statistical and signal-processing techniques to analyze the altered dynamics of sleep-wake behavior in mice with disrupted orexinergic systems; modeled the action of orexin at the network level; and described a Hodgkin-Huxley-type model orexin neuron. Recent work has analyzed the role of progressive orexin cell loss in a novel rodent model of narcolepsy. Orexin neurons are also glucose-sensing and, therefore, are ideally situated to integrate information between sleep/wake and metabolic systems.

Stochastic and deterministic contributions to the fine architecture of sleep-wake behavior

The fine architecture of sleep-wake behavior reflects the underlying deterministic and stochastic processes that produce it and provides an important constraint for models seeking to represent this system. Systematic analysis of the effects of different kinds of noise on resulting dynamics has provided insights into the interaction between deterministic and stochastic elements of the system and revealed some fundamental asymmetries in the network dynamics producing states of wake and sleep. Current work includes assessing the relative contributions of stochastic and deterministic elements to fundamental features of sleep-wake behavior including comparative analyses across different mammalian species and includes collaborations with several labs investigating sleep in mice, rats, cats, degus, and humans.