Dopamine modulation of escape movements in larval zebrafish

Graduation Date

2012

Document Type

Thesis

Program

Other

Program

Thesis (M.A.)--Psychology, Academic Research: Biological Psychology, 2012

Committee Chair Name

Ethan Gahtan

Committee Chair Affiliation

HSU Faculty or Staff

Keywords

Humboldt State University -- Theses -- Psychology, Zebrafish, Motor, Mauthner, Dopamine, Escape

Abstract

Dopamine is a neurotransmitter involved in the control of motor coordination. Its modulation of inhibitory and excitatory processes in the motor pathways of the brain and spinal cord influences initiation and control of movement behaviors. This study examined the effects of dopamine on the physiological responses of a pair of hindbrain neurons, called the Mauthner cells, and the associated behavioral effects, in larval zebrafish. The Mauthner pair coordinate swift escape responses to sensory stimuli in zebrafish. Evidence from previous studies suggests that the Mauthner neuron receives input from dopamine neurons in the brain, and my experiments were to determine whether dopamine actually modulates Mauthner cell activity. Physiological recordings of the Mauthner and other descending neurons were done using intracellular calcium imaging, with an escape-eliciting tap stimulus applied during cell recording. The effects of bath-applied dopamine on Mauthner neuron responses were assessed by comparing responses before, during, and after dopamine treatment in the same larvae (within subjects design), and, in separate experiments, by comparing responses in dopamine treated larvae and untreated control larvae. Dopamine exposure produced increases in Mauthner calcium response magnitude and likelihood of behavioral response to stimuli. These differences were not found in the control experiments. In the context of this and previous research, dopamine appears to facilitate escape-related swimming in larvae while inhibiting spontaneous swimming activity.

https://scholarworks.calstate.edu/concern/theses/2f75rb449

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