Posts Tagged ‘research’

How The Brain Works: Visual Working Memory

Thursday, February 9th, 2012

Scientists from Cardiff University in Wales, have contributed a new and important piece of information to our understanding of working memory processing — specifically visual working memory. Unlike image recognition (known as encoding) which activates specific brain regions depending on the type of image, the short term storage of images in working memory involves more generalized brain activation.

David E. J. Linden, Nikolaas N. Oosterhof, Christoph Klein, and, Paul E. Downing detailed their findings in the Journal of Neurophysiology.

Using fMRI (real time brain imaging) the researchers had eighteen participants view and memorize three sequentially presented images from one of four categories: faces, bodies, scenes, or flowers.

Ten seconds later they displayed an image from the same category and asked the participants to indicate whether this new image matched one of the previous three images–a test of visual working memory.  The test was repeated eighty times (with twenty iterations for each of the four categories). The researchers addressed the possibility that the participants were remembering the images as words rather than pictures they played the radio as background noise during the entirety of the experiment.

Region Activated for Working Memory Storage

The fMRI data showed that the brain areas known to be activated during visualization (encoding) at the rear of the brain declined in activity during the 10 second delay. Whereas areas near the front of the brain–in the prefrontal cortex and medial frontal gyrus–became active during the long delay while the participants tried to hold the images in working memory.

The same frontal areas activated during the working memory test for all visual stimuli, regardless of the category, suggesting they activate in a more general pattern for visual working memory with no particular specialization based on image category.

“We conclude that principles of cortical activation differ between encoding and maintenance of visual material,” the authors said.

Exercise That Stimulates Brain Plasticity

Thursday, September 17th, 2009

“This New York Times article about brain change in mice reports that mice who underwent intensive treadmill exercise showed more plastic change than mice who underwent normal treadmill exercise or none.

Reading on the article also has some interesting bits about other studies involving exercise and cognition:

“…fundamental questions remain, like whether exercise must be strenuous to be beneficial. Should it be aerobic? What about weight lifting? And are the cognitive improvements permanent or fleeting?

“Other recent studies provide some preliminary answers. In an experiment published in the journal of the American College of Sports Medicine, 21 students at the University of Illinois were asked to memorize a string of letters and then pick them out from a list flashed at them. Then they were asked to do one of three things for 30 minutes — sit quietly, run on a treadmill or lift weights — before performing the letter test again. After an additional 30-minute cool down, they were tested once more. On subsequent days, … the students were noticeably quicker and more accurate on the retest after they ran compared with the other two options, and they continued to perform better when tested after the cool down.

““It appears that various growth factors must be carried from the periphery of the body into the brain to start a molecular cascade there,” creating new neurons and brain connections, says Henriette van Praag, an investigator in the Laboratory of Neurosciences at the National Institute on Aging. For that to happen, “you need a fairly dramatic change in blood flow,” like the one that occurs when you run or cycle or swim.” van Praag says.

“Jen cautions against assuming human bodies work exactly like those of rats. But there are lessons from his work. “It would be fair to say that any form of regular exercise,” he says, if it is aerobic, “should be able to maintain or even increase our brain functions.””