Forget gigabytes. Even the most powerful computers available today are mere playthings compared to the complexity, efficiency, and information processing capacity of the human brain. Underlying the brain's far superior design are the billion-million or so connections between brain cellscalled synapsesthat form vast neural networks in which brain cells, or neurons, are each connected to thousands of other neurons. These networksand their ability to be shaped by experienceenable us to receive, process, store, and retrieve all manner of information about our world. Unfortunately, the extremely tiny size of synapses and the limitations of conventional experimental techniques have hampered detailed studies of these essential structures. (One trillion synaptic compartments, or "dendritic spines," could fit into a thimble). Now, scientists at Cold Spring Harbor Laboratory have overcome these technical obstacles to gain an extremely close look at the properties of dendritic spines and synapses that govern brain function.
"Our findings reveal fundamental properties of synapses that enables them to trigger the changes in neurons that underlie learning and memory," says Karel Svoboda, the principal author of the study which will be published tomorrow in Nature. Svoboda, an investigator of the Howard Hughes Medical Institute at Cold Spring Harbor Laboratory, helped pioneer the use of a high resolution imaging technique called "two-photon microscopy" in neuroscience.
In the current study, Svoboda and his colleague Bernardo Sabatini electrically stimulated brain neurons and used two-photon microscopy to watch as calcium rushed-in to single dendritic spines of these neurons (see figure). These measurements enabled the researchers to determine the number and type of "calcium channels" present at synapses in a region of the brain important for learning and memory, the hippocampus. Calcium channels are molecular gates that open in response to e
Contact: Michael Stebbins
Cold Spring Harbor Laboratory