Poster abstracts
Poster number 90 submitted by Kaarthik Abhinav Balakrishnan
Identifying internal states that underlie thermal navigation behavior in larval zebrafish using Hidden Markov models and in-vivo functional imaging
Kaarthik Abhinav Balakrishnan (Biophysics Graduate Program), Jamie D. Costabile (Department of Neuroscience, The Ohio State University), Martin Haesemeyer (Department of Neuroscience, The Ohio State University)
Abstract:
Animals navigate their surroundings to reach their goals, which include foraging, thermoregulation and exploration. Modulation of internal temperature is a crucial task for survival, and this is critical for ectotherms which lack physiological mechanisms to control their temperature. We study the navigational strategies adopted by larval zebrafish, which are ectotherms, by tracking their position while freely swimming in a thermal gradient chamber. Since they swim in discrete bouts, the entire experiment can be decomposed into these separate movements which can be analyzed using different bout related parameters- namely bout distance, bout turn angles and inter-bout intervals. We find that these quantities vary with the temperature of the chamber. Our goal is to model how larval zebrafish integrate temperature information to modulate their bout parameters. Previous research on a bout-by-bout level revealed that bout distances and bout turn angles increase with temperature, while inter-bout intervals decrease with temperature. While this presents an intuitive basis for avoiding hot temperatures, the robust avoidance of cold temperatures is not as obvious. Our preliminary analysis indicates a weak autocorrelation in consecutive bout distances and bout turn angles, leading us to speculate the presence of longer timescale control of movements. We model this using a combination of Generalized Linear Model and a Hidden Markov model (GLM-HMM) to represent the internal states that control the turn angles in successive bouts. This model would provide an insight into the decisions made during thermal navigation and highlight the differences between cold and hot temperature navigation. Subsequently, we identify neural correlates that represent information about temperature using in-vivo functional imaging through two-photon fluorescence microscopy.
Keywords: Computational Neuroscience, Zebrafish, Fluorescence microscopy