Have you ever wondered what happens in our brain when we learn to ride a bike? Why is it that once we learn to execute movements and maintain balance, we remember it for life? And how do we remember in great detail special moments in our lives? The answer to how we learn and remember things lies in a fascinating phenomenon known as synaptic plasticity.
First described by Donald Hebb in his Hebbian theory in 1949, and demonstrated in the laboratory by Terje Lmo and Timothy Bliss in 1973synaptic plasticity is defined as the brain’s ability to adapt and change in response to experience. Simply put, they are the changes that occur in the connections between neuron synapses as a result of their activity.
The brain is like a road network
One of the key players in synaptic plasticity is the hippocampus, a brain structure located in the medial temporal lobe. The hippocampus plays a fundamental role in the formation and consolidation of memory, especially episodic memorythat is, personal experiences. It acts as the conductor of the orchestra in the learning and remembering process, coordinating the neuronal activity of different brain regions to store and retrieve important information.
Imagine your brain as a road network, where neurons are the vehicles and synapses are the intersection points where the roads cross. Synaptic plasticity will be the ability to modify these intersections. Some may be expanded to allow more traffic flow (synaptic strengthening or LTP), while others may be closed or reduced (synaptic weakening or LTD). Whether one thing or another happens will depend on their use: synapses strengthen or weaken depending on how much they are used.
For example, when we learn something new, such as playing a musical instrument, the synaptic connections involved in that process tend to strengthen. This is because the neural activity associated with that specific experience strengthens its connections, making it easier for us to remember the information in the future.
Intense emotions strengthen the connections between neurons
A curious fact is that we are able to clearly remember the day we met that special person, even if many years have passed, but we are not able to remember what we ate last week.
Well, this is also directly related to synaptic plasticity in the hippocampus and its connection with other brain areas such as the carrywhich is the command center of emotions.
When we experience very intense emotions, such as love, joy or fear, the synaptic connections in our brain become stronger, anchoring those memories with intense emotional bonds. Thus, synaptic plasticity not only allows us to remember past events, but also to relive the associated emotions, creating a rich tapestry of experiences that shape our identity and our perception of the world.
Adapt or die
Plasticity phenomena also play a crucial role in recovery from brain injuries. After brain damage, such as a stroke, the brain can reorganize and recruit neighboring neurons to take over the functions of injured areas. This phenomenon, known as compensatory plasticityis possible thanks to the brain’s ability to form new synaptic connections and reconfigure neuronal circuits.
Unfortunately, the hippocampus is also implicated in neurodegenerative diseases such as Alzheimer’s disease. In this pathology, an accumulation of toxic proteins occurs that seriously affects the hippocampus, causing neuronal damage and preventing normal synaptic plasticity from occurring. As the disease progresses, the hippocampus gradually deteriorates, resulting in significant loss of memory and other cognitive functions.
This has led researchers to explore therapeutic approaches that can modulate synaptic plasticity, such as the use of drugs that improve LTP and protect the synapses from damage caused by toxic proteins, thus reserving the function of the hippocampus and slowing the progression of the disease.
Additionally, this research is also shedding light on possible non-pharmacological prevention strategies, including regular physical exercise, a healthy diet, and cognitively stimulating activities such as listening to musicwhich could promote synaptic plasticity and protect the brain against deterioration associated with the disease.
Flexible algorithms like neurons
From the formation of memories to recovery after brain injuries, synaptic plasticity is essential for the proper functioning of the human brain.
Understanding these processes is essential to develop new therapies and prevention strategies that can help combat diseases. But the importance of synaptic plasticity is not limited to the brain: researchers are studying how to mimic the human brain using algorithms inspired by synoptic plasticity. This could lead to the development of more flexible and adaptable artificial intelligence systems, capable of learning and improving with experience, just like humans.
