Researchers have revealed that an assembly of actin filaments is crucial for long-term potentiation (LTP), an increase in synapse sensitivity that helps to lay down memories.
In the July 13, 2009 issue of the Journal of Cell Biology, Rex et al. reveal that LTP's actin reorganization occurs in two stages that are controlled by different pathways, a discovery that helps explain why it is easy to encode new memories but hard to hold onto them.
Alzheimer’s disease - Causes, Symptoms, Diagnosis, Stages, Types, Prevention, Prognosis & Treatment
Alzheimer's disease is a progressive neurodegenerative disease affecting memory and thinking and making the person increasingly dependent on others.
Alzheimer's disease is a progressive neurodegenerative disease affecting memory and thinking and making the person increasingly dependent on others.
Rex et al. tackled the question by dosing slices of rat hippocampus with adenosine, a naturally occurring signal that squelches LTP. Adenosine prevents phosphorylation and inactivation of cofilin, an inhibitor of actin filament assembly, the team found. Cofilin's involvement, in turn, implicates signaling cascades headed by GTPases, such as the RhoA-ROCK and Rac-PAK pathways. The researchers showed that a ROCK inhibitor stalled actin polymerization and resulted in a short-lived LTP. A Rac-blocking compound had no effect.
That doesn't mean the Rac-PAK pathway isn't involved in LTP, however. The team discovered that the Rac inhibitor prolonged cells' vulnerability to a molecule that prevents the stabilization of new actin filaments. That result led Rex et al. to conclude that the two pathways exert their effects at different points. The Rho-ROCK pathway initiates the cytoskeletal changes of LTP, and the Rac-PAK pathway solidifies them so that heightened synapse sensitivity can persist. The researchers hypothesize that one pathway encodes memories, while the other makes sure they stick around.
Dyslexia - Causes, Symptoms, Diagnosis, Treatment
Dyslexia is a reading disability that occurs when the brain does not properly recognize and process certain symbols.
Dyslexia is a reading disability that occurs when the brain does not properly recognize and process certain symbols.
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About Schizophrenia
Schizophrenia is a mental disorder characterized by symptoms of thought, behavior and social problems.
Schizophrenia is a mental disorder characterized by symptoms of thought, behavior and social problems.
Primary Insomniacs Use Increased Brain Activation Than Normal Sleepers, During Working Memory Task
A new study says that patients suffering from chronic primary insomnia (PIs) have higher levels of brain activation compared to normal sleepers during a working memory test.
A new study says that patients suffering from chronic primary insomnia (PIs) have higher levels of brain activation compared to normal sleepers during a working memory test.
