News reports of research into memory January 2003

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January 2003

Gene linked to poor episodic memory

Brain derived neurotrophic factor (BDNF) plays a key role in neuron growth and survival and, it now appears, memory. We inherit two copies of the BDNF gene - one from each parent - in either of two versions. Slightly more than a third inherit at least one copy of a version nicknamed "met," which the researchers have now linked to poorer memory. Those who inherit the “met” gene appear significantly worse at remembering events that have happened to them, probably as a result of the gene’s effect on hippocampal function. Most notably, those who had two copies of the “met” gene scored only 40% on a test of episodic (event) memory, while those who had two copies of the other version scored 70%. Other types of memory did not appear to be affected. It is speculated that having the “met” gene might also increase the risk of disorders such as Alzheimer’s and Parkinsons.
The study was reported in the January 24 issue of Cell. Full reference
http://www.nih.gov/news/pr/jan2003/nimh-23.htm
http://www.eurekalert.org/pub_releases/2003-01/niom-hga012203.php
http://news.bbc.co.uk/1/hi/health/2687267.stm

Biofeedback training for the brain

“Neurofeedback” is a biofeedback technique involving showing people their own brainwaves on a computer screen and training them in altering the brainwaves. It has reportedly had some success in treating attention deficit hyperactivity disorder, epilepsy and alcoholism. A new study has attempted to apply the technique to memory. Forty people were given a series of words which related to specific categories. They were then given the categories and asked to recall related words. Those who had experienced neurofeedback training recalled 81.6% of the words, compared to an earlier memory test in which they recalled 70.6%. Control subjects recalled 75.1% compared to their earlier score of 72.5%.
The study is published in the International Journal of Psychophysiology. Full reference http://www.eurekalert.org/pub_releases/2003-01/icos-rfl012203.php

Second language best taught in childhood

Sadly, it does appear that the easiest time to learn a second language is, indeed, in childhood. An imaging study has found that when grammatical judgement in the second language was compared to grammatical judgement in first language (as evidenced by performance on sentences with grammatical mistakes), there was no difference in brain activation in those who learned the second language as children. However, people who acquired the second language late and with different proficiency levels displayed significantly more activity in the Broca's region during second language grammatical processing. "This finding suggests that at the level of brain activity, the parallel learning of the two languages since birth or the early acquisition of a second language are crucial in the setting of the neural substrate for grammar."
The research was published in Neuron. Full reference

Detection of foreign faces faster than faces of your own race

A recent study tracked the time it takes for the brain to perceive the faces of people of other races as opposed to faces from the same race. The faces were mixed with images of everyday objects, and the subjects were given the distracting task of counting butterflies. The study found that the Caucasian subjects took longer to detect Caucasian faces than Asian faces. The study complements an earlier imaging study that showed that, when people are actively trying to recognize faces, they are better at recognizing members of their own race. [see Why recognizing a face is easier when the race matches our own]
The report will appear in Clinical Neurophysiology.
http://news.bmn.com/news/story?day=030108&story=1

Imaging study confirms link between exercise and cognitive function

A number of studies have suggested a link between exercise and cognitive function in older adults, but now an imaging study shows that there are actual anatomical differences in the brains of physically fit versus less fit older adults (over 55). Specifically, they found very distinct differences in the gray and white matter in the frontal, temporal, and parietal cortexes. With aging, these tissues shrink, a reduction closely matched by declines in cognitive performance. Fitness, it appears, slows that decline. A related study, published in March, suggests that women may benefit more from exercise than men.
The report appeared in the February issue of the Journal of Gerontology: Medical Sciences. Full reference
http://www.eurekalert.org/pub_releases/2003-01/uoia-sif012703.php

Calorie restriction reduces age-related brain cell death

A recent rat study has shown that certain proteins that increase with age and are linked to cell death were significantly reduced in the brains of rats whose calories were limited (but nutritionally dense, to guard against malnutrition). Moreover, the levels of a beneficial protein known to protect against neuron death were twice as high in older rats whose calories were restricted by 40%. This is consistent with a number of studies of other species that have found calorie restriction not only boosts life span and general health but also increases mental capacity.
The findings were published on Jan. 2 in the online edition of the journal of the Federation of American Societies for Experimental Biology. Full reference
http://www.eurekalert.org/pub_releases/2003-01/uof-usc010903.php

Neural circuits that control eye movements play crucial role in visual attention

Everyone agrees that to improve your memory it is important to “pay attention”. Unfortunately, noone really knows how to improve our ability to “pay attention”. An important step in telling us how visual attention works was recently made in a study that looked at the brain circuits that control eye movements. It appears that those brain circuits that program eye movements also govern whether the myriad signals that pour in from the locations where the eyes could move should be amplified or suppressed. It appears that the very act of preparing to move the eye to a particular location can cause an amplification (or suppression) of signals from that area. This is possible because humans and primates can attend to something without moving their eyes to that object.
The report was published in the Jan. 23 issue of Nature. Full reference
http://www.eurekalert.org/pub_releases/2003-01/pu-ssh012303.php

Learning a sequence with explicit knowledge of that sequence involves same

Imaging studies have found that sequence learning accompanied with awareness of the sequence activates entirely different brain regions than learning without awareness of the sequence. It has not been clear to what extent these two forms of learning (declarative vs procedural) are independent. A new imaging study devised a situation where subjects were simultaneously learning different sequences under implicit or explicit instructions, in order to establish whether, as many have thought, declarative learning prevents learning in procedural memory systems. It was found that procedural learning activated the left prefrontal cortex, left inferior parietal cortex, and right putamen. These same regions were also active during declarative learning. It appears that, in a well-controlled situation where procedural and declarative learning are occurring simultaneously, the same neural network for procedural learning is active whether that learning is or is not accompanied by declarative knowledge. Declarative learning, however, activates many additional brain regions.
Their findings appeared in the September 2002 edition of the Journal of Neurophysiology. Full reference

More details about how memories are formed in the hippocampus

We know how important the hippocampus is in forming memories, but now, using newly developed imaging techniques, researchers have managed to observe how activity patterns within specific substructures of the hippocampus change during learning. The study identified areas within the hippocampus (the cornu ammonis and the dentate gyrus) as highly active during encoding of face-name pairs. This activity decreased as the associations were learned. A different area of the hippocampus (the subiculum) was active primarily during the retrieval of the face-name associations. Activity in the subiculum also decreased as retrieval became more practiced.
The report appeared in the Jan. 24 edition of Science. Full reference
http://www.eurekalert.org/pub_releases/2003-01/uoc--som012303.php

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