Evidence that angiogenesis lags behind neuron and astrocyte growth in experience-dependent plasticity.

Bill Greenough's work on the cell biology of information storage suggests that we cannot understand the mechanism of long-term memory without understanding the series of cellular transactions that drive coordinated structural changes in neurons, glia, and blood vessels. Here, we show that after 4 days of differential housing, neuropil of EC cortex has expanded significantly, but the vasculature has not, resulting in a dilution of the blood supply. Significant growth of neurons and astrocytes has been reported within this time period, suggesting expression of synaptic plasticity might involve temporally coordinated genomic responses by both neurons and glia. Given that astrocytes appear to couple neuronal and vascular growth during development, we hypothesize that they may also mediate the onset of angiogenesis in response to neural demand in the EC brain. Further, these results may imply that a neuron's capacity for plasticity could be constrained by the rate of vascular expansion.