The Surprising Link Between DNA, Inflammation, and Long-Lasting Memories

Wednesday - April 10 2024, 18:27 UTC - 7 months ago

A new study suggests that breaking and repairing DNA in neurons may pave the way for long-lasting memories. Surprisingly, inflammation in certain neurons in the brain’s hippocampal region is essential for making these memories. The hippocampus is a key brain region for encoding memories, and scientists have long believed that rewiring the brain's connections is a fast and unstable process. However, the study found that a subset of neurons alter their connections to encode long-lasting memories, by recruiting proteins that usually fight off bacteria and cause inflammation. This process, called synaptic plasticity, allows for rapid changes in overall neural connections and helps memories form.

Some memories last a lifetime. The awe of seeing a full solar eclipse. The first smile you shared with your partner. The glimpse of a beloved pet who just passed away in their sleep. Other memories, not so much. Few of us remember what we had for lunch a week ago. Why do some memories last, while others fade away? Surprisingly, the answer may be broken DNA and inflammation in the brain. On the surface, these processes sound utterly detrimental to brain function. Broken DNA strands are usually associated with cancer, and inflammation is linked to aging.

But a new study in mice suggests that breaking and repairing DNA in neurons paves the way for long-lasting memories. We form memories when electrical signals zap through neurons in the hippocampus, a seahorse-shaped region deep inside the brain. The electrical pulses wire groups of neurons together into networks that encode memories. The signals only capture brief snippets of a treasured experience, yet some can be replayed over and over for decades (although they do gradually decay like a broken record).

Like artificial neural networks, which power most of today's AI, scientists have long thought that rewiring the brain's connections happens fast and is prone to changes. But the new study found a subset of neurons that alter their connections to encode long-lasting memories. To do this, strangely, the neurons recruit proteins that normally fend off bacteria and cause inflammation.

'Inflammation of brain neurons is usually considered to be a bad thing, since it can lead to neurological problems such as Alzheimer's and Parkinson's disease,' said study author Dr. Jelena Radulovic at Albert Einstein College of Medicine in a press release. 'But our findings suggest that inflammation in certain neurons in the brain's hippocampal region is essential for making long-lasting memories.' .

Should I Stay or Should I Go? We all have a mental scrapbook for our lives. When playing a memory—the whens, wheres, whos, and whats—our minds transport us through time to relive the experience. The hippocampus is at the heart of this ability. In the 1950s, a man known as H.M. had his hippocampus removed to treat epilepsy. After the surgery, he retained old memories, but could no longer form new ones, suggesting that the brain region is a hotspot for encoding memories.

But what does DNA have to do with the hippocampus or memory? It comes down to how brain cells are wired. Neurons connect with each other through little bumps called synapses. Like docks between two opposing shores, synapses pump out chemicals to transmit messages from one neuron to another. Depending on the signals, synapses can form a strong connection to their neighboring neurons, or they can dial down communications. This ability to rewire the brain is called synaptic plasticity. Scientists have long thought it's the basis of memory. When learning something new, electrical signals flow through neurons triggering a cascade of molecules. These stimulate genes that restructure the synapse to either bump up or decrease their connection with neighbors. In the hippocampus, this 'dial' can rapidly change overall neural connections, so one experience may be woven into the rich tapestry of our mind.