These tiny protrusions from the surface of dendrites measure about 1 micrometer in length. Dendritic spine structure is clearly important for normal brain function because when brain function is impaired, such as in conditions of mental retardation, epilepsy, and stroke, the dendritic spines are either gone, or have highly distorted shapes and sizes. These methods allow us to assess the structural basis of synaptic function using multiple approaches. In the mature brain, more dendritic spines and synapses form when synaptic activity is reduced or blocked. This finding suggests that spine formation is homeostatically regulated by global activity levels.
More spines form when a neuron receives insufficient levels of activation.
The new spine synapses can then be incorporated into new networks to support new memories. Future goals are to develop animal models and add molecular biological tools to these structural and physiological approaches to investigate the synaptic basis of learning and memory. Effect of inactivity on spinogenesis during development. Early synaptic changes induced by slice preparation. Gold labeling of activated synapses.