June 13 Nature article: Deciphering the Neuronal Code
Buzsaki, professor at Rutgers-Newark's Center for Molecular and Behavioral Neuroscience, said that the research published in the journal Nature, "Spike train dynamics predicts theta-related phase precission in hippocampal pyramidal cells," revealed new aspects of the code by which neurons (brain cells) communicate with each other. Buzsaki's collaborators include Kenneth D. Harris, Darrell A. Henze, Hajime Hirase, Xavier Leinekugel, George Dragoi, and Andras Czurko.
Buzsaki compares the way brain neurons communicate to a talking drum. "Perhaps the most fundamental problem of neuroscience is to decipher the code which the neuron uses to encode its message into a sequence of electrical events," said Buzsaki. His collaborator, Ken Harris, notes that evidence over the last decade "strongly suggests a temporal code is employed, and that the precise rhythm of the neuronal drum beat is also used to convey information."
Buzsaki's research found that the rhythms a neuron may play are not random, "but obey certain rules, which are followed by the whole population of neurons." He said the new findings provide clues to how brain rhythms assist brain cells to represent information in the temporal domain, similar to melodies played on a musical instrument. Timing is of the essence in the brain. Moreover, Buzsaki said researchers "showed that this complex behavior can be explained by the biophysical properties of single neurons rather than by complicated rules within neuronal networks as previously suggested."
June 14 Science article: Wiring the Newborn Brain
To get a better understanding of how an immature brain network develops over time, Buzsaki's research appearing in the journal Science, "Correlated Bursts of Activity in the Neonatal Hippocampus In Vivo," reveals findings that have possible implications for a newborn's brain. Buzsaki collaborated with Xavier Leinekugel, Rustem Khazipov, Robert Cannon, Hajime Hirase, and Yehezkel Ben-Ari from the Inserm, Marseilles, France.
Previous Buzsaki research has indicated that in a sleeping adult's brain, hippoccampal neurons discharge together in bursts, which serves to consolidate information learned during the day into long-term memories. In this research on newborn rat pups, Buzsaki indicates that similar patterns of wave-like bursts were found. "In fact, they are the only patterns in the hippocampus of the newborn that can be reasonably associated with plasticity of neuronal connections," he added.
Buzsaki noted that the old-fashioned assumption about brain development was that the environment imposes its effect by way of inputs, and the inputs determine how the connections are wired. But he said that view no longer holds since "all parents know that drugs that have beneficial effects in adults can have all sorts of deleterious effects in the brains of children."
Buzsaki indicated that the wave-like bursts play a critical role in shaping the connections in the newborn brain. "Since we all believe that the developing brain is the most plastic, the question is: What patterns secure this?" Since the rat pups have closed eyes and ears, their brain filters the outside information, and "during the second week of life, the adult-type patterns emerge," Buzsaki said. This research was made possible by using new techniques for measuring cellular activity in the hippocampus. Some of these techniques, and more advanced methods, are part of Buzsaki's recent $1.4 million NIH grant.
$1.4 Million NIH Grant: How Memories Are Formed
The grant from the National Institutes of Health will enable Buzsaki and his co-researchers to further their brain memory research. "The main goal is to understand the formation of memories and the underlying plastic mechanisms in the brain," said Buzsaki. "Current imaging methods such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) do not have either the time or spatial resolution for this task."
Under the NIH grant, the researchers will be taking advantage of the "fast progress in silicon technology and laser-scanning microscopy to directly study the subcellular elements that play a critical role in changing connectivity among neurons and are part of the overall process leading to memory formation," Buzsaki added.
Buzsaki compares the silicon brain probes to earthquake monitoring stations. "To determine the precise position and timing of seismographic activity requires a lot of information from many recording stations to find out what is happening. Similarly, in the brain, multiple monitoring sites at the microscopic level allow researchers to monitor numerous neuronal coalitions to find out what their collective message might be."
Assisting the brain memory research are Kenneth Harris, Hajime Hirase, and Joseph Csicsvari, research associates in Buzsaki's laboratory at the Center for Molecular and Behavioral Neuroscience at Rutgers-Newark (www.cmbn.rutgers.edu).
For more information contact Buzsaki at buzsaki@axon.rutgers.edu.
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Science