Cellular Mechanisms of Startle Response: a study of M-cells in the Xenopus laevis tadpole

One of the most important decisions an organism can make is how it will respond to a potential predator. One of the more studied mechanisms of startle response is in teleost fish and amphibians, which is mediated by a pair of neurons known as the Mauthner cells (M-cells). These M-cells are responsible for the left and right turning in response to potentially dangerous stimuli, via linking sensory processing in the brain to motor output in the spinal cord. In this study, I explore the properties of the local field potentials (LFPs) generated by the M-cell and its surrounding inputs to better understand the cellular mechanisms of the startle response. In particular, I identified what components of the LFP were consistent across brains, and then pharmacologically blocked different synaptic receptors to determine the nature and origin of LFP components. The results of this study yielded four notable findings: (1) in addition to chemical transmission, electrical signals are responsible for part of the main excitatory component of the LFP; (2) there is an early excitatory component that is entirely pre-synaptic; (3) the NMDA receptors of this network contribute to the timing and efficiency of the main spiking component; (4) there are potentially additional excitatory inputs contributing to the latter excitation of the LFP. The results of this study can be used as a foundation for further exploration of the M-Cell system in Xenopus tadpoles