Certain classes of dendrites contain small projections referred to as dendritic spines that increase receptive properties of dendrites to isolate signal specificity. Increased neural activity and the establishment of long-term potentiation at dendritic spines change the sizes, shape, and conduction. This ability for dendritic growth is thought to play a role in learning and memory formation. There can be as many as 15,000 spines per cell, each of which serves as a postsynaptic process for individual presynaptic axons. Dendritic branching can be extensive and in some cases is sufficient to receive as many as 100,000 inputs to a single neuron.