Monthly Archives: January 2020

What Comes First: Phrenic Motor Neuron Loss or Neuromuscular Junction Dysfunction?
Ann Mary Wilfred
Fourth Year
Health sciences major with biomedical specialization
McMaster University

My Research Project

Drawing of the chest cavity with the diaphragm colored in red.

As we age, there are many changes that happen in our body. One of these changes is the loss of phrenic motor neurons (PhMNs), a specific type of neuron that controls the diaphragm, the main muscle we use for breathing.

In older adults, the consequence of this loss of neurons is the inability to clear the airways through high-force behaviors like coughing and sneezing. Not being able to clear the airways may lead to infection and sometimes, death. With aging, the connection between these PhMNs and the muscle fibers it innervates—called the neuromuscular junction (NMJ)—breaks down because the PhMNs withdraw their connection from these muscles in a process called pre-synaptic withdrawal. The problem is that we do not know which event happens first: PhMN loss or pre-synaptic withdrawal.

My project aimed to chronicle a timeline of these events using a specific type of imaging technique called confocal microscopy. Being able to identify the sequence of events may help us pinpoint areas of therapeutic intervention in order to prevent or delay PhMN loss and NMJ dysfunction.

Realities of Research

Although I have participated in previous research activities, this summer fellowship was my first experience in a wet lab. It was a very valuable opportunity because I learned a wide variety of wet lab techniques, such as immunohistochemistry staining and how to handle rodents. What surprised me most was how much trouble-shooting was required— there are so many things that can go wrong! My project was mainly focused on imaging PhMNs. The biggest learning highlight of this project was learning how to use a confocal microscope and quantitatively analyzing the images. Initially, I felt intimidated because the process seemed so complex, and this was a very advanced and expensive piece of equipment. However, after imaging and analyzing so many samples, I am proud to say that I feel comfortable using this type of technique. I was happy to see that the experiments worked and the results were what I expected:that pre-synaptic withdrawal precedes PhMN loss in the NMJ and that large PhMNs seem to be more vulnerable to this loss.

Life as a Scientist

Working in the lab was an amazing experience! There were moments where it was very hectic, days when I had to go home later than usual or even times when I felt very frustrated because the work was tedious and laborious. Despite all of this, the experience was very rewarding because of the friends I made in the lab, the valuable networking opportunities I was engaged in, the important connections I made and most of all, the unique satisfaction I experienced when the experiments worked properly. In the end, I had really good data that I can contribute to a paper or publication.

I am grateful to have had the opportunity to work in a very supportive and welcoming lab environment; my lab mates, research mentor and principal investigator were always so receptive to my questions and concerns and helped mold me into the scientist and researcher that I am today.

It feels amazing to know that my research is contributing in a meaningful way to the larger goal of improving age-related respiratory dysfunction in hopes of someday helping so many people.

Ann Mary Wilfred is a senior in the Bachelor of Health Sciences (biomedical sciences specialization) at McMaster University in Hamilton, Ontario, Canada. She is a 2019 Undergraduate Student Research Fellow (UGSRF) working under the mentorship of Dr. Gary C. Sieck at Mayo Clinic in Rochester, Minn. Ann’s fellowship is funded by the American Physiological Society. After graduation, Ann plans to pursue a career in medicine, specializing to become a pediatric neurosurgeon, while also continuing her involvement in neuroscience and physiology research.

Biomechanics to improve running performance
Gemma Malagón
2019, senior
Biomedical engineering
Tecnológico de Monterrey, Mexico

My Research Project

As a Fellow from the American Physiological Society (APS), Hearst Undergraduate Summer Research Fellowship, I was grateful to have had an opportunity to work under Dr. Arellano at the University of Houston at the Center for Neuromotor and Biomechanics Research.

My research this summer focused on the biomechanics of arm swing across different walking speeds and its effect on the metabolic cost. Our main objective was to better understand the passive and active contributions by examining the electromyographic (EMG) activity of the muscles involved in arm swing, with a special focus on understanding how changes in EMG amplitude in the upper limb varied across walking speed.

The data acquisition consisted of:

  1. Measurements of oxygen consumption and carbon dioxide production using indirect calorimetry, which is a process that measured the amount of heat that was released or absorbed during a chemical reaction;
  2. XYZ coordinates of joint positions, which has the objective to understand the kinematics of the body;
  3. Ground reaction forces; and
  4. Muscle activity of arm muscles of interest.

These measurements allowed us to compute and compare metabolic power, joint angles and mechanics and average muscle activity patterns when walking with and without arm swing.

Realities of Research

The research that I conducted was exciting and it was a wonderful experience working in the lab. In the beginning, I spent most of my time reading articles and doing research on my assigned project. I had an engineering background prior to my summer research, so one of the aims of my research project was to develop an efficient MATLAB code to process and analyze the EMG data collected on the studies.

I have learned to measure my progress due to the number of setbacks I had, which also helped me realize different paths which brought me closer to reaching my goal. I have learned more than I could ever hope and was fortunate to have had the opportunity to work—even for a little while—with some of the most talented and coolest people in the U.S.

Life as a Scientist

I made the decision to study biomedical engineering with a concentration in research driven by my desire to contribute to fundamental breakthroughs in medicine and become a better Mexican-researcher. This past summer, besides working on my own research, I’ve was involved in many lab projects, so I realized how amazing it is when you work with people who share the same passion as you. The truth is, having to work eight hours a day during the week, and some days even more, might be tiring! This was especially true when I would have to take the bus for two hours to get to the lab and two more hours to get back home. However, it was a unique experience that not everyone is willing to take advantage of. Participating in this program not only widened my research experience, but it has helped me on my path towards a master’s degree, which I plan to pursue after I graduate.


Christopher J. Arellano, Rodger Kram. Journal of Experimental Biology 2014 217: 2456-2461; doi: 10.1242/jeb.100420

Gemma Malagón is a senior majoring in biomedical engineering at the University of Tecnológico de Monterrey in Mexico. She is a Hearst Undergraduate Summer Research Fellow working in Dr. Arellano’s lab at the University of Houston, Health and Human Performance Department. Gemma’s fellowship is funded by the American Physiological Society and Hearst Foundations. After graduation, Gemma plans to pursue a master’s degree in clinical and sports engineering.


I would like to express my deepest appreciation to Hearst Foundations and the American Physiological Society (APS) for my research fellowship, and to Dr. Christopher J. Arellano, which the completion of my internship would not have been possible without his support and mentorship.