In addition to the milieu of systems this nutritionally essential element contributes to in the human body, the divalent cation zinc also participates in neuronal signalling within the nervous system. Specifically, a subset of zinc within the brain is located in the synaptic vesicles of some glutatmatergic neurons and can be released at the presynaptic terminal in an activity-dependent manner. The location of zinc releasing neurons and pathways, and the co-release of synaptic zinc with neurotransmitters such as glutamate, supports the involvement of synaptic zinc in neuromodulation and, specifically, in cortical plasticity. In fact, chelation of extracellular zinc in vitro has been demonstrated to inhibit LTP, while sensory deprivation or sensory stimulation in intact animals can lead to activity-dependent increases or decreases of synaptic zinc, respectively.