By K J Foxhall 
This article links with the theme of May 2026 which gave us a reminder about what the hippocampus is all about. As this is also the name for the magazine, you will see a lot of information, but the main point to remember (excuse the pun), is that the hippocampus is all about encoding and storing memory, so it is an important conduit.
For a long time, the prevailing belief was that the human brain was like a concrete block; once it hardened in early adulthood, its structure was fixed. We now know that nothing could be further from the truth. Your brain is a dynamic, ever-changing ecosystem, constantly rewiring itself in response to your experiences, thoughts, and environment.
This remarkable ability is known as neuroplasticity. When it comes to learning and memory, neuroplasticity works hand-in-hand with a small, seahorse-shaped structure deep within the brain called the hippocampus.
Here is a look at exactly how this biological partnership forms the foundation of who we are and what we remember.
The hippocampus: The brain’s printing press
Located in the inner folds of the temporal lobe, the hippocampus is the central hub for memory formation. You can think of it as the brain’s printing press for declarative memories (facts and events) and spatial memories (navigation and environments).
When you learn someone’s name, read a new concept, or navigate a new city, the sensory information is first funnelled into the hippocampus. However, the hippocampus is not where memories live permanently. Instead, it acts as a temporary sorting and processing centre. It links the different aspects of a memory (the sights, sounds, and emotions) and eventually helps transfer them to the outer layer of the brain (the cerebral cortex/neocortex1) for long-term storage.
Neuroplasticity in action: How connections change
To understand how the hippocampus processes these memories, we have to look at the microscopic level of neurons (brain cells). Neuroplasticity in the hippocampus primarily occurs in two major ways:
1. Synaptic plasticity
Neurons communicate with each other across tiny gaps called synapses. When you learn something new, the neurons in your hippocampus fire in a specific sequence. As the famous neuroscientific saying goes; ‘Neurons that fire together, wire together.’
Long-Term Potentiation (LTP): When a specific pathway of neurons is activated repeatedly (like when you study a concept over and over), the connection between those synapses physically strengthens. The sending neuron becomes better at releasing neurotransmitters, and the receiving neuron becomes more sensitive to them. This enhanced signal transmission is the biological basis of learning.
Long-Term Depression (LTD): Conversely, if a neural pathway is rarely used, the connections weaken. This allows the brain to clear out irrelevant information and remain efficient.
2. Neurogenesis
The hippocampus is one of the very few regions in the adult human brain capable of neurogenesis (the birth of entirely new neurons). Specifically, a subfield of the hippocampus located in the brain’s temporal lobe called the dentate gyrus, continually produces new brain cells throughout your life.
These fresh neurons are highly adaptable and are easily recruited into new memory circuits, making them crucial for distinguishing between similar memories and learning new things.
The memory lifecycle
The collaboration between neuroplasticity and the hippocampus can be broken down into three core phases:
- Encoding: You experience something new. The sensory inputs trigger a unique pattern of neural firing in the hippocampus. Synaptic plasticity begins as these temporary connections are formed.
- Consolidation: This is where the memory is stabilised. The hippocampus repeatedly replays the neural firing patterns associated with the new memory, especially while you are asleep. Over time, this repetitive firing permanently strengthens the connections in the cerebral cortex, freeing up the hippocampus to encode new information.
- Retrieval: When you try to remember an event, the brain activates the network of neurons that were wired together during encoding and consolidation. The more you retrieve a memory, the more you reinforce that neural pathway, making it easier to recall in the future.
Optimising your brain’s plasticity
Because neuroplasticity is driven by behavior and environment, you have an incredible amount of agency over your brain’s health. The hippocampus is highly responsive to lifestyle factors:
- Sleep: Sleep is non-negotiable for memory. It is during deep sleep that the hippocampus acts as an off-line processor, replaying the day’s events and consolidating them into long-term storage.
- Aerobic exercise: Cardiovascular exercise dramatically boosts the production of Brain-Derived Neurotrophic Factor (BDNF). BDNF is often described as ‘Miracle-Gro for the brain’, it promotes the survival of existing neurons and encourages the growth of new ones in the hippocampus.
- Novelty and challenge: Learning a new language, picking up an instrument, or simply changing your routine forces the hippocampus to forge new neural pathways, keeping the brain agile and resilient.
- Stress management: Chronic stress floods the brain with cortisol. Over time, sustained high levels of cortisol can actually shrink the hippocampus and halt neurogenesis, severely impairing memory formation.
Your brain is a lifelong work in progress. By understanding how the hippocampus utilises neuroplasticity, we can view our daily habits not just as physical maintenance, but as the very architects of our minds and memories.
- The neocortex is the outer, highly-folded layer of the mammalian brain. It comprises the largest part of the cerebral cortex and is responsible for higher-order cognitive functions such as conscious thought, sensory perception, spatial reasoning, language, and executive control – there is more to this an further descriptions will be detailed in other articles / posts. ↩︎