Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/25861
Title: ORCHESTRATING FEAR RESPONSES IN LARVAL ZEBRAFISH: A ROLE FOR THE HABENULA
Authors: LEE MIN ALETHEIA
Keywords: zebrafish, conditioning, optogenetic, control, habenula, anxiety
Issue Date: 16-Aug-2010
Source: LEE MIN ALETHEIA (2010-08-16). ORCHESTRATING FEAR RESPONSES IN LARVAL ZEBRAFISH: A ROLE FOR THE HABENULA. ScholarBank@NUS Repository.
Abstract: Animals learn to fear stimuli that predict danger, and may flee or freeze in defensive response to those threats. However, pre-exposure to uncontrollable aversive events produce a helpless state that impairs subsequent active avoidance learning, induced by a cascade of stress-induced neural activation in brainstem nuclei. Here, transgenic zebrafish were used to test the involvement of specific habenula neurons in orchestrating active fear responses, as the habenula regulates monoaminergic neurons in the midbrain. In an escapable aversive conditioning paradigm, larval zebrafish learned to avoid a mild electric shock that was predicted by light. KillerRed-mediated optical disruption of habenula afferents caused a deficit in the acquisition of active avoidance, despite the controllable outcome. Instead, larvae switched to freezing-like responses over the course of training, and displayed increased startle. Silencing habenula efferents with expression of the light chain of tetanus toxin similarly altered the conditioned response. These findings identify components of the neural network regulating fear responses in vertebrates, and suggest that the septal-habenula pathway provides a signal for control over a stressor. When disrupted, animals appear unable to downregulate anxiety, and exhibit helpless behavior as if the outcome is uncontrollable. Perturbation of this pathway and consequent dysregulation of monoaminergic systems may contribute to the pathological conditions associated with anxiety disorders.
URI: http://scholarbank.nus.edu.sg/handle/10635/25861
Appears in Collections:Master's Theses (Open)

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