25 Years Later: How the 2000 Nobel Prize Transformed Neuroscience and Medicine


By Joao L. de Quevedo, MD, PhD, Director, Center for Interventional Psychiatry UTHealth Houston
August 11, 2025

Celebrating a Quarter Century of Scientific Breakthroughs

In 2025, we mark the 25th anniversary of one of the most influential Nobel Prizes in neuroscience and medicine. Awarded in 2000, the Nobel Prize in Physiology or Medicine recognized three pioneering scientists—Arvid Carlsson, Paul Greengard, and Eric Kandel—for unraveling how brain cells communicate, adapt, and store information. Their discoveries have shaped the modern fields of psychiatry, neurology, and molecular neuroscience.

A quarter-century later, their legacy continues to guide the development of treatments for Parkinson’s disease, depression, schizophrenia, Alzheimer’s disease, and more. Let’s revisit the scientific breakthroughs that earned them this highest honor—and why their work still matters.

Arvid Carlsson: Dopamine and Parkinson’s Disease

Swedish pharmacologist Arvid Carlsson (1923–2018) fundamentally changed how we understand dopamine. In the 1950s, he discovered that dopamine is not just a precursor to norepinephrine—it’s a neurotransmitter in its own right, especially critical for motor control.

Carlsson’s research showed that dopamine deficiency in the brain leads to Parkinsonian symptoms, and that administering L-DOPA could reverse them. This directly led to L-DOPA becoming the cornerstone of Parkinson’s disease treatment—a clinical breakthrough that remains vital today.

💡 25 years on, Carlsson’s work still forms the pharmacological backbone of movement disorder therapy.

Paul Greengard: Signal Transduction Inside the Cell

American neuroscientist Paul Greengard (1925–2019) discovered how neurotransmitters like dopamine and serotonin change the internal state of neurons. Rather than acting only through fast ion channels, they initiate a slower cascade of intracellular events, notably through protein phosphorylation.

Greengard’s findings laid the foundation for understanding how psychiatric drugs work at the molecular level, influencing the design of antidepressants, antipsychotics, and mood stabilizers.

💡 Today’s psychopharmacology owes much of its molecular basis to Greengard’s discoveries.

Eric Kandel: The Molecular Biology of Memory

Austrian-American neuroscientist Eric Kandel (b. 1929) tackled the elusive mystery of memory. Working with the sea slug Aplysia, he showed that learning changes the strength of synaptic connections. He distinguished between:

  • Short-term memory: Changes in existing proteins.
  • Long-term memory: Requires new gene expression and protein synthesis, leading to structural changes in the brain.

Kandel’s research connected synaptic plasticity with memory formation, a concept now foundational to neuroscience and neuropsychiatry.

💡 His work continues to inform efforts to understand and treat cognitive disorders like dementia and PTSD.

A Unified Legacy: Communication, Plasticity, and Neuropsychiatric Disease

Together, Carlsson, Greengard, and Kandel:

  • Identified what neurotransmitters do (Carlsson)
  • Explained how they act inside cells (Greengard)
  • Revealed why they matter for learning and memory (Kandel)

These three domains—neurotransmission, signal transduction, and synaptic plasticity—remain cornerstones of modern neuroscience. Their discoveries have profoundly impacted how we treat conditions from Parkinson’s disease to major depression, and how we understand the biological basis of behavior.

The 2000 Nobel Prize was not just a scientific milestone—it was a turning point for clinical neuroscience.

A Quarter Century Later, Still Guiding the Future

The 2000 Nobel laureates did more than explain how neurons talk to each other—they transformed medicine, psychiatry, and neuroscience for generations to come. As we celebrate the 25th anniversary of their recognition, we are reminded that foundational research into the brain’s basic mechanisms can ultimately change how we treat some of the world’s most disabling diseases.

Key References

  1. Carlsson A, Lindqvist M. (1963). Effect of chlorpromazine or haloperidol on formation of 3-methoxytyramine and normetanephrine in mouse brain. Acta Pharmacol Toxicol, 20, 140–144.
    https://doi.org/10.1111/j.1600-0773.1963.tb01730.x
  2. Carlsson A, Falck B, Hillarp NA. (1962). Cellular localization of brain monoamines. Acta Physiol Scand Suppl, 56(199), 1–28.
  3. Greengard P. (2001). The neurobiology of slow synaptic transmission. Science, 294(5544), 1024–1030.
    https://doi.org/10.1126/science.294.5544.1024
  4. Kandel ER. (2001). The molecular biology of memory storage: A dialogue between genes and synapses. Science, 294(5544), 1030–1038.
    https://doi.org/10.1126/science.1067020
  5. Nobel Foundation. The Nobel Prize in Physiology or Medicine 2000.
    https://www.nobelprize.org/prizes/medicine/2000/summary/
  6. Kandel ER, Schwartz JH, Jessell TM, et al. (2013). Principles of Neural Science (5th ed.). McGraw-Hill.

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