Dendritic spines are cytoplasmic protrusions that develop directly or indirectly from the filopodia of neurons. Dendritic spines mediate excitatory neurotransmission and they can isolate the electrical activity generated by synaptic impulses, enabling them to translate excitatory afferent information via several types of plastic changes, including neoformation, disappearance, redistribution and changes in geometric shape. The fine line between normal and abnormal excitatory neurotransmission is mediated by the concerted action of glutamate-mediated stimulation and calcium ion entry into spines. Moreover, within the range of normal excitatory activity, dendritic spines undergo specific plastic changes to regulate different forms of afferent information that are often related to distinct modes of cognition-related electrophysiological stimulation, such as long-term potentiation or long-term depression. (Contains 1 figure.)