By Sofía Garcíá
Photo of Henry Molaison via Jenni Ogden
Overview
The case of H.M. (Henry Molaison) was one of the most important in the field of psychology because it helped us understand one of the most vital functions for everyone: memory. His case shed light on the brain's function and how it correlates with memory. It also revealed how damaging it can be to the performance of daily activities.
The Case
After suffering a bicycle accident during his childhood in the 1930s, the patient, known as H.M., began to suffer a series of epileptic seizures. The seizures progressed and prevented him from living a normal life. The seizures continued into adulthood, and H.M. was no longer able to work. H.M. finally agreed to a radical surgery that would remove several parts of his brain. The surgery removed the damaged areas of the brain: the hippocampus, part of the amygdala, and the hippocampal gyrus. On the one hand, the surgery was successful because he experienced fewer seizures. However, his family and friends soon noticed he struggled to remember things and had major memory gaps from the past 11 years. Furthermore, he lost the ability to form new memories.
Photo via Duke University
The Study
Following this, psychologist Dr. Brenda Milner began treating and studying him for over 30 years. While she was treating him, H.M. was unable to remember his name. Milner successfully taught him basic learning tasks, but the next day, he was unable to remember how or when he had learned them. From then on, several studies began on motor skill learning, leading to the conclusion that we have declarative memory, which is responsible for learning and remembering verbal information (facts and events), and non-declarative memory, which refers to the learning of skills, habits, simple forms of conditioning, and perceptual and emotional learning.
What Was Discovered?
Brenda Milner demonstrated that memory has other forms of organization (unlike what was thought at the time, which was believed to be concentrated solely in the temporal lobe). This resulted in the knowledge of long-term and short-term memory. These types, moreover, function independently and are stored in different places. Henry's short-term memory was intact; however, long-term memory, which is responsible for permanently storing information, was not functioning. After several years of research, Milner concluded that the hippocampus, which she had removed from the patient, was responsible for permanently storing memories.
Conclusion
This study also revealed that we have specialized areas in our memory for each type of memory; the area used to memorize songs is not the same area we use to remember faces or to do math. As can be seen, H.M.'s case has been one of the most important in neuropsychology. Through it, we were able to exhaustively study the types of memory, and this changed the understanding we had of this function. Despite the disastrous consequences for Molaison, his case was of helped to better understand the importance of memory in our daily lives.
About the Author
Sofía is a high school student from Spain. She's always been good at biology and chemistry, but it wasn't until she watched an episode of House M.D. in quarantine that she decided to become a doctor. Since then, every time she watches a medical series, she memorizes the diseases and procedures in the hopes of understanding a little more about the fascinating world of medicine. Sofia has been suffering from chronic migraines for over a year and can confidently say she is an expert on this condition. She wanted to write this to share her knowledge with anyone who wants to read more about it. This is Sofia's fourth post for the blog!
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