Neural Network Theory Publication (1943) - Warren McCulloch and Walter Pitts published "A Logical Calculus of the Ideas Immanent in Nervous Activity," establishing the theoretical foundation for neural networks and computational neuroscience.
First Clinical Use of Positron Emission Tomography (PET) for Brain Imaging (1976) - This technological breakthrough at Washington University enabled researchers to visualize metabolic activity in the living human brain for the first time.