AI-rewritten: This is a summary of an article from The Conversation, rewritten by AI (Qwen, running locally) to make it easier to read. The facts come from the original article – read it for the full story.

---

Kimberlee D’Ardenne explains that the brain’s complexity within a cubic millimeter makes mapping it difficult. To understand this, scientists follow a pattern: visualize the brain, measure its function, and then control it. Santiago Ramon y Cajal won the 1906 Nobel Prize for painting neurons using silver stains developed by Camillo Golgi. Later, researchers in the 1970s used anterograde and retrograde tracing to map pathways. Today, electron microscopy and expansion microscopy allow scientists to see connections at atomic resolution, while functional MRI measures blood flow to track activity. In 2003, the Nobel Prize recognized techniques that made fast imaging sequences possible.

Alan Hodgkin and Andrew Huxley won the 1963 Nobel Prize for measuring electrical impulses called action potentials. Modern probes can now listen to hundreds of neurons simultaneously. A series of studies published in 2025 found that 95% of the brain is active during decision-making, not just areas typically linked to it. Alim-Louis Benabid developed deep brain stimulation in the late 1980s to treat Parkinson’s disease. This method acts like a pacemaker but influences all nearby cells, so researchers are now developing more precise tools.

Optogenetics allows scientists to control neurons millisecond by millisecond using light. Researchers won the 2026 Nobel Prize for this technique. Neurons do not naturally respond to these lights, so scientists use harmless viruses to instruct them to produce light-sensitive proteins. This process is similar to designer receptors exclusively activated by designer drugs, or DREADDs, which control neurons chemically instead of with light. Several clinical trials are testing optogenetics and DREADDs for conditions like epilepsy, Alzheimer’s disease, Parkinson’s disease, and vision loss.