Neuroscience and Clustered Plasticity

Branching of cell dendrites in rat brain
Another fascinating article in the ever-growing body of knowledge about the way our brain works appeared in The New York Times this week.

An essential question has always been how the brain is able to absorb and store information in such a tiny place as one dendrite, a small stalk-like bit of a bit of a neuron in a bit of the brain called the hippocampus. (The average human brain has about 100 billion neurons, and about 1,000 times that many synapses.)

The Journal Nature reported the results of a study which begins to answer this question.

The NY Times article states: Researchers at the Howard Hughes Medical Institute in Maryland stimulated not a single cell but a single dendritic spine, one of the hairlike growths that sprout from a cell’s branching arms.

Brain cells communicate with their neighbors by sending a chemical burst from the tips of these spines, across a space called the synapse to the tip of a spine on the next cell. If the chemical bath is strong enough, the receiving spine bulges forward — strengthening the connection between the spines. This is thought to be the fundamental process underlying learning.

But the researchers, Christopher D. Harvey and Karel Svoboda, found something unusual when they stimulated a single spine. Not only did the spine bulge, but it also somehow made its neighbors more sensitive to chemical signals — standing ready, in effect, to digest any spillover of information. Imagine every neighbor on the block calling up to offer a corner of his basement for storage, just in case.

Neuroscientists had theorized that this effect, called clustered plasticity, might help account for the tremendous capacity of the brain, but they had not seen it in action. Read more.

Click here for earlier posts about the brain.