Dataset Information

Brain dysfunction during warming is linked to oxygen limitation in larval zebrafish.

ABSTRACT: Understanding the physiological mechanisms that limit animal thermal tolerance is crucial in predicting how animals will respond to increasingly severe heat waves. Despite their importance for understanding climate change impacts, these mechanisms underlying the upper thermal tolerance limits of animals are largely unknown. It has been hypothesized that the upper thermal tolerance in fish is limited by the thermal tolerance of the brain and is ultimately caused by a global brain depolarization. In this study, we developed methods for measuring the upper thermal limit (CT_max) in larval zebrafish (Danio rerio) with simultaneous recordings of brain activity using GCaMP6s calcium imaging in both free-swimming and agar-embedded fish. We discovered that during warming, CT_max precedes, and is therefore not caused by, a global brain depolarization. Instead, the CT_max coincides with a decline in spontaneous neural activity and a loss of neural response to visual stimuli. By manipulating water oxygen levels both up and down, we found that oxygen availability during heating affects locomotor-related neural activity, the neural response to visual stimuli, and CT_max. Our results suggest that the mechanism limiting the upper thermal tolerance in zebrafish larvae is insufficient oxygen availability causing impaired brain function.

SUBMITTER: Andreassen AH

PROVIDER: S-EPMC9522358 | biostudies-literature | 2022 Sep

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Brain dysfunction during warming is linked to oxygen limitation in larval zebrafish.

Andreassen Anna H AH Hall Petter P Khatibzadeh Pouya P Jutfelt Fredrik F Kermen Florence F

Proceedings of the National Academy of Sciences of the United States of America 20220919 39

Understanding the physiological mechanisms that limit animal thermal tolerance is crucial in predicting how animals will respond to increasingly severe heat waves. Despite their importance for understanding climate change impacts, these mechanisms underlying the upper thermal tolerance limits of animals are largely unknown. It has been hypothesized that the upper thermal tolerance in fish is limited by the thermal tolerance of the brain and is ultimately caused by a global brain depolarization. ...[more]

PMID: 36122217

Similar Datasets

Project description:Animals engaged in naturalistic behavior can exhibit a large degree of behavioral variability even under sensory invariant conditions. Such behavioral variability can include not only variations of the same behavior, but also variability across qualitatively different behaviors driven by divergent cognitive states, such as fight-or-flight decisions. However, the neural circuit mechanisms that generate such divergent behaviors across trials are not well understood. To investigate this question, here we studied the visual-evoked responses of larval zebrafish to moving objects of various sizes, which we found exhibited highly variable and divergent responses across repetitions of the same stimulus. Given that the neuronal circuits underlying such behaviors span sensory, motor, and other brain areas, we built a novel Fourier light field microscope which enables high-resolution, whole-brain imaging of larval zebrafish during behavior. This enabled us to screen for neural loci which exhibited activity patterns correlated with behavioral variability. We found that despite the highly variable activity of single neurons, visual stimuli were robustly encoded at the population level, and the visual-encoding dimensions of neural activity did not explain behavioral variability. This robustness despite apparent single neuron variability was due to the multi-dimensional geometry of the neuronal population dynamics: almost all neural dimensions that were variable across individual trials, i.e. the "noise" modes, were orthogonal to those encoding for sensory information. Investigating this neuronal variability further, we identified two sparsely-distributed, brain-wide neuronal populations whose pre-motor activity predicted whether the larva would respond to a stimulus and, if so, which direction it would turn on a single-trial level. These populations predicted single-trial behavior seconds before stimulus onset, indicating they encoded time-varying internal modulating behavior, perhaps organizing behavior over longer timescales or enabling flexible behavior routines dependent on the animal's internal state. Our results provide the first whole-brain confirmation that sensory, motor, and internal variables are encoded in a highly mixed fashion throughout the brain and demonstrate that de-mixing each of these components at the neuronal population level is critical to understanding the mechanisms underlying the brain's remarkable flexibility and robustness.

Dataset Information

Brain dysfunction during warming is linked to oxygen limitation in larval zebrafish.

Publications

Brain dysfunction during warming is linked to oxygen limitation in larval zebrafish.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets