Term of Award

Summer 2019

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Department of Biology

Committee Chair

Vinoth Sittaramane

Committee Member 1

Christine Bedore

Committee Member 2

Sophie George

Abstract

Complex memory has evolved because it benefits animals in all areas of life, such as remembering the location of food or conspecifics, and learning to avoid dangerous stimuli. Advances made by studying relatively simple nervous systems, such as those in gastropod mollusks, can now be used to study mechanisms of memory in more complex systems. Cephalopods offer a unique opportunity to study the mechanisms of memory in a complex invertebrates. The dwarf cuttlefish, Sepia bandensis, is a useful memory model because its fast development and small size allows it to be reared and tested in large numbers. However, primary literature regarding the behavior and neurobiology of this species is lacking. This research determined that juvenile S. bandensis exhibited short term memory (STM) and long term memory (LTM). To assess memory in dwarf cuttlefish, a memory test was conducted which utilized the predatory attack in cuttlefish. It was found that 4 week old dwarf cuttlefish retained memory of the experiment up to 4 days. Using an automated tracking software called DanioVision, this research found that cuttlefish selectively inhibit the tentacle striking phase of their predatory behavior, without inhibiting the attention and positioning phases. Determining the molecular mechanisms underlying memory is key to understanding how memory is manifested in the form of altered behavior. At the cellular level, memories are formed by altering the physical and chemical properties within specific neural circuits. The transcription factor, CREB, is responsible for transcribing genes required for initiating these long-term neuronal changes. Using immunohistochemistry, a molecular assay was developed to determine whether CREB is activated in cuttlefish arms during the memory experiment. Trained cuttlefish had a greater number of CREB positive cells in the epithelium of the arm than controls. Trained cuttlefish also had a greater average number of CREB-positive cells in positive suckers than untrained cuttlefish. These results suggest that CREB activation may result from behavioral training in cuttlefish. Lastly, it was found that the distal tip of the arm contained more CREB-positive cells than the proximal part of the arm. Spatial activation of CREB may occur predominantly in the distal portion of the arm. By locating CREB for the first time in a cephalopod, this research presents dwarf cuttlefish as interesting models for studying the molecular mechanisms of memory formation.

Research Data and Supplementary Material

Yes

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