Neuronal strategies for meeting the right partner during brain wiring

•A series of developmental steps restricts neuronal contacts during brain wiring.•Restricting contacts in time and space allows for more promiscuous synapse formation.•Positional strategies are dynamic processes in time and space.•Directional instructions are syntheses of molecular, cellular and tissue properties. Two neurons can only form a synapse if their axonal and dendritic projections meet at the same time and place. While spatiotemporal proximity is necessary for synapse formation, it remains unclear to what extent the underlying positional strategies are sufficient to ensure synapse formation between the right partners. Many neurons readily form synapses with wrong partners if they find themselves at the wrong place or time. Minimally, restricting spatiotemporal proximity can prevent incorrect synapses. Maximally, restricting encounters in time and space could be sufficient to ensure correct partnerships between neurons that can form synapses promiscuously. In this review we explore recent findings on positional strategies during developmental growth that contribute to precise outcomes in brain wiring.