INNATE FEAR MODELING THROUGH PREDATOR ODOR EXPOSURE IN AWAKE RODENTS – AN FMRI STUDY

Open Access
Author:
Messner, Christopher K
Area of Honors:
Biology
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Dr. Nanyin Zhang, Thesis Supervisor
  • Dr. Bernhard Lüscher, Honors Advisor
  • Dr. Yingwei Mao, Faculty Reader
Keywords:
  • Functional Magnetic Resonance Imaging
  • Neuroscience
  • Stress
  • Innate Fear
  • Odor Exposure
Abstract:
Observing and interpreting brain activity is a complicated science. Pinpointing distinct regions of the brain responsible for certain emotions is an ongoing effort. Stress and innate fear are noteworthy emotions for their implications in human health. Utilizing a unique, awake-animal fMRI paradigm, I here attempted to contribute to the current understanding of brain activity associated with innate fear. Several questions were asked relating to how innate fear activated the brain and how exposed rats would respond to innately (unlearned) fearful stimuli. An innately fearful odor (fox urine) was administered to the rats and the resulting BOLD activation was observed during imaging, while the behavioral responses were observed over a week later. Exposure to fox urine resulted in altered BOLD signals in six regions of the brain: the retrosplenial cortex, the pituitary gland, the amygdala, the hypothalamus, the bed nucleus of the stria terminalis, and the anterior cingulate cortex. Behavioral responses of rats exposed to fox urine in the so-called Elevated Plus Maze indicated trends for elevated levels of anxiety, reminiscent of human Post-Traumatic Stress Disorder (PTSD). To conclude, further experimentation with a greater sample size was deemed necessary for several future exploits. These potential further inquiries include obtaining more information about PTSD, the retrosplenial cortex, as well as remaining unanswered questions about fMRI and behavior.