The case of Henry Molaison, famously known as HM, provided groundbreaking insights into the human brain and memory. Understanding what type of long term memory was intact in HM is crucial for grasping the architecture of our recollections and how they are stored and retrieved.
The Power of Doing What Type Of Long Term Memory Was Intact In Hm
One of the most remarkable discoveries from studying HM was the preservation of his procedural memory. This is the memory of how to do things, the skills and habits we acquire over time. Even though HM couldn’t remember meeting a new doctor from one day to the next, he could still learn new motor tasks. For example, he could learn to trace a star shape while looking at his hand in a mirror, a task that requires coordination and learning. This demonstrated that the brain could still form new long-term memories for skills, even without the ability to recall factual information or personal experiences.
This ability to learn new skills, or procedural memory, highlights a critical distinction in how our brains store information:
- Declarative Memory (knowing that): This includes facts and events, like remembering your birthday or the capital of France. HM had a severe deficit in this area.
- Non-declarative Memory (knowing how): This encompasses skills and habits, such as riding a bike or playing a musical instrument. HM’s procedural memory remained largely intact.
The experiments conducted with HM, particularly those involving learning new motor tasks, revealed that the brain has distinct systems for different types of memory. Here’s a simplified look at the types of long-term memory, with HM’s situation in focus:
| Type of Memory | HM’s Ability |
|---|---|
| Episodic Memory (events) | Severely Impaired |
| Semantic Memory (facts) | Severely Impaired |
| Procedural Memory (skills) | Intact |
The fact that HM could learn new procedures and exhibit improved performance over time, despite having no conscious recollection of the learning process, was a pivotal finding. It suggested that the brain structures responsible for forming new episodic and semantic memories (like the hippocampus) were different from those involved in learning new motor skills.
To delve deeper into the fascinating world of memory and the enduring legacy of HM’s case, consider the resources available in the section following this text. You’ll find detailed explanations and further explorations of these concepts.