Zinc plays a critical role in regulating how neurons communicate with one another, affecting memories and learning, U.S. and Canadian researchers say.Study authors Xiao-an Zhang, now a chemistry professor at the University of Toronto, Scarborough, and colleagues at the Massachusetts Institute of Technology and Duke University in North Carolina, said researchers have been trying to crack the 50-year-old mystery of what role the mineral has on the brain.Fifty years ago, scientists found high concentrations of zinc in synaptic vesicles -- a portion of the neuron that stores neurotransmitters. But it was hard to determine just what zinc\'s function was, the researchers said.In the study, the researchers designed a chemical ZX1 that would bind with zinc rapidly after it was released from the vesicles but before it could complete its journey across the synapse.Using the chemical, the researchers were able to observe how neurons behaved when deprived of zinc, Zhang said.\"As a chemist, I\'m proud that I can make a contribution to neuroscience,\" Zhang said in a statement.The researchers studied neurons in the brain region hippocampus, which is associated with learning and memory formation.The study found removing zinc interfered with a process called long-term potentiation, which strengthens the connection between two neurons, and seems to be important for memory and learning.