Honors Theses

Date of Award

Spring 5-9-2020

Document Type

Undergraduate Thesis


Communication Sciences and Disorders

First Advisor

Tossi Ikuta

Second Advisor

Saumen Chakraborty

Third Advisor

John Samonds

Relational Format



The raphe-hippocampal tract links the raphe nuclei to the hippocampus and is responsible for the production of the neurotransmitter serotonin. The hippocampus is key in regulating emotional and stress responses. This study utilized diffusion tensor imaging which uses Functional Magnetic Resonance Imaging to provide scans of the brain for analyzing differences in the raphe-hippocampal tract as one ages. In this specific study, 491 samples were visually analyzed to gather data about the fractional anisotropy of the raphe nuclei in both male and female brains ranging from 6 to 85 years old. Through the ranking of images, some were discarded, and all were evaluated based on the raphe-hippocampal tract highlighted in red and blue on the images. After analysis, the data allowed for a significant regression equation to be found. Thus, the predicted FA of the DRN-hippocampal tract is equal to 0.023 + 0.00046 (age) – 3.84 (sex). This means that as one increases in age, FA increases in the raphe-hippocampal tract. This is due to the fact that the brain shows decreasing connectivity in more external structures, creating an imbalance leading to decreased mood.

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