When I moved from Brazil to the United States to train as a neuroscientist, I was shocked to discover that most of our ‘knowledge’ about the human brain in fact came from another species: the mouse. This struck me as pretty strange. After all, it wasn’t the mouse brain that put us on the Moon or that decoded the human genome. It was the human brain in all its complexity that generated our understanding of life and of the laws that govern the Universe.
Nonetheless, as a postdoctoral researcher, I set about busily learning how to dissect mouse brains. I hoped to find out more about the major regions and important structures associated with mental and neurological disorders such as autism and epilepsy – and, ultimately, how to fix them. I practised and practised, until I was finally an expert in the anatomy of the mouse nervous system. But it was bloody work, and I paid the price at night. In my dreams, I replayed the vivid experience of removing the brains from tiny skulls and slicing them up. Something about these nightmares was telling me not to continue down this road. Eventually, I mustered the courage to challenge my colleagues: what if the diseases we want to cure, and the answers we want, won’t be found in the mouse brain?
Many scientists would remind me of how similar these two species are in terms of brain structure. However, despite their similarities, these two species took distinct evolutionary paths, adapting the brains for their respective lifestyles and evolutionary niches. This explains why cures in mice don’t always translate into cures for humans. But there’s a reason why neuroscientists tend to rely on mouse models – it’s more practical than testing on people. Historically, however, it’s left us with many unanswered questions, such as when does the first human neuron fire? And when does the human cortex form? [Continue reading…]