Posts Tagged ‘brain research’

The Workings of Working Memory

Friday, January 27th, 2012

Synaptic Communication

How do we keep thoughts in our mind? It seems a simple question until we remind ourselves of the brain as a dynamic labyrinth of neurons constantly firing and receiving electrical signals. But researchers from the University of Wisconsin-Madison believe they’ve figured out how working memory holds a piece of information. The holder of a thought, they have discovered, is a molecular sensor that controls nerve cell communication keeping a message present and active even long after its delivery.

“The sensor could play a role in keeping a thought ‘on line’ until it is either lost or burned into longer-lasting forms of memory,” says the study lead Dr. Edwin Chapman, a professor at the UW School of Medicine and Public Health.

Most communication between synapses occurs instantaneously–an electrical impulse spurs calcium in the sending cell to release a burst of neurotransmitter into the receiving cell. This process takes just milliseconds to play out.

The Wisconsin scientists focused instead on a second, slower, asynchronous communication phase, in which residual levels of calcium continue to cause the release of neurotransmitters over several seconds.

“We knew that different calcium sensors controlled these two distinct phases of synaptic transmission,” says Chapman, based in the Department of Neuroscience.

The team theorized that slow transmission, with its maintenance of a communication state for a longer time period, might be the key to the retention of thoughts in working memory. They found that they were able to change the speed of slow release with higher and lower levels of a protein called Doc2 without impacting fast release.

“Doc2 took its time responding to calcium, unlike synaptotagmin, which responded immediately,” Chapman says.

The research could eventually produce practical results providing insight into conditions such as autism and schizophrenia. “Defects in release mechanisms are seen in many nerve diseases,” says Chapman.


See Brain Region, See Other Brain Region Run

Friday, February 26th, 2010

A novel study shows that when learning new words the part of the brain we use depends on whether the words are nouns or verbs.

“Learning nouns activates the left fusiform gyrus, while learning verbs switches on other regions (the left inferior frontal gyrus and part of the left posterior medial temporal gyrus)”, says Catalan researcher Antoni Rodríguez-Fornells, co-author of the study from the Cognition and Brain Plasticity Unit of the University of Barcelona.

He and neurologist Thomas F. Münte from the Otto-von-Guericke University in Magdeburg, in Germany, reported their findings of neural differences in acquiring new nouns and verbs in the journal Neuroimage.

By studying real time scans showing brain activation during a language learning exercise the researchers confirmed prior observations that our brains handle nouns and verbs in different ways.

The scientists inserted nonsense words into otherwise meaningful sentences, and then asked the study participants to derive the meaning of the inserted word – “Joe bought his mom a grimo of flowers for Mother’s day…” for instance, indicates that the word “grimo” means “bunch.”

“This task simulates, at an experimental level, how we acquire part of our vocabulary over the course of our lives, by discovering the meaning of new words in written contexts”, explains Rodríguez-Fornells. “This kind of vocabulary acquisition based on verbal contexts is one of the most important mechanisms for learning new words during childhood and later as adults, because we are constantly learning new terms”.

They measured responses to 80 new nouns and 80 new verbs.

“[The] results suggest that the same regions previously associated with the representation of the meaning of nouns and verbs are also associated with establishing correspondences between these meanings and new words, a process that is necessary for learning a second language”, says Rodríguez-Fornells.