A part of the brain known as the basal ganglia may act to filter out irrelevant information from memory, increasing its apparent capacity, finds a study in the January 2008 issue of Nature Neuroscience. The study could help to explain why some people are better at remembering things than others.
The ability to hold information 'online' so that it is immediately accessible is known as working memory, and its capacity is strictly limited. These variations are not just due to having a larger or smaller memory store, but also due to differences in how effectively irrelevant items are kept out of memory.
Torkel Klingberg and colleagues find in a functional imaging study that people who can hold more items in working memory have more activity in the basal ganglia when distracting stimuli are present during a task. An auditory cue informed subjects whether an upcoming visual display would contain irrelevant distracters (along with the targets). When this cue occurred, neural activity increased in the basal ganglia and the prefrontal cortex, before the visual display appeared. This increased activity suggests readiness to filter out the upcoming distracters.
Greater activity in the globus pallidus, a subregion of the basal ganglia, correlated with less unnecessary storage in another part of the brain, the posterior parietal cortex, which is sensitive to the amount of information held in memory. Consider the posterior parietal cortex as an exclusive nightclub and the basal ganglia as the bouncer: the size of the nightclub influences its crowding, but the effectiveness of the bouncer is important too.
Torkel Klingberg (Karolinska Institute, Stockholm, Sweden)
Abstract available online.
(C) Nature Neuroscience press release.
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