Graduation Date

Fall 2025

Document Type

Thesis

Program

Master of Arts degree with a major in Psychology, option Academic Research

Committee Chair Name

Ethan Gahtan

Committee Chair Affiliation

Cal Poly Humboldt Faculty or Staff

Second Committee Member Name

Karen Kiemnec-Tyburczy

Second Committee Member Affiliation

Cal Poly Humboldt Faculty or Staff

Third Committee Member Name

Amanda Hahn

Keywords

Perineuronal net, Zebrafish, Trout, Critical periods, Neural plasticity, Extracellular matrix, Model organisms, Central nervous system, Brain, Comparative neuroscience

Subject Categories

Psychology

Abstract

Perineuronal nets (PNNs) are specialized extracellular matrix structures that surround certain types of neurons in the central nervous system. Research from the past few decades has cemented PNNs as an integral player in the closure and onset of critical periods, memory modulation, and neural plasticity. These effects are thought to occur when PNNs form around a neuron and structurally stabilize its synaptic connections. PNNs have been directly linked to behavioral changes, making them of interest to psychologists as well as neuroscientists. Several PNN components, such as Hapln1 and aggrecan such as have been found in zebrafish, a teleost fish (Kang et al., 2008). While this suggest the presence of PNNs in the zebrafish extracellular matrix, mammalian-like PNNs have not been directly observed. I tested zebrafish brain sections for PNNs using Wisteria Floribunda Agglutinate (WFA) labeling--a well-established method for visualizing PNNs--in sections alongside brain sections from mouse and trout (another teleost fish). Mouse brains are known to have PNNs, therefore, the presence of PNNs in zebrafish and trout were judged based on their similarity to PNNs expected to be found in mouse brain samples. By testing these three species, this study had a positive control for methods (finding expected PNNs in mice) and two teleost fish to assess the generalization of my findings to the teleost class. Our methods revealed PNNs within mice as expected but failed to find any staining within zebrafish or trout that differed statistically from background fluorescence. Our conclusions are limited secondary to the variety of brain regions sampled, and I cannot conclusively rule out the presence of PNNs of the tested species. Zebrafish are a widely used research model in neuroscience, and confirming the presence of PNNs would widen the application of powerful zebrafish research methods to the many open questions about PNNs.

Citation Style

APA

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