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The Capacity of Visual Short-Term Memory is Set Both by Visual Information Load and by Number of Objects

✍ Scribed by Alvarez, G.A.; Cavanagh, P.

Book ID
121662273
Publisher
SAGE Publications
Year
2004
Tongue
English
Weight
152 KB
Volume
15
Category
Article
ISSN
0956-7976

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Theta bandwidth determines human visual
Theta bandwidth determines human visual working memory capacity Human visual short term memory (VSTM) is capacity limited1. The neurophysiological basis for this limitation is, however, currently unknown. Here we apply the principle of efficient information transfer, derived from communications theory, to provide a mechanistic account of VSTM capacity. Shannon's information theory states that to increase the capacity of information encoded along a frequency axis, it is more efficient to expand the bandwidth than to increase the transmitted power for a given level of noise2. By applying Shannon's principles to human magnetoencephalography (MEG) recordings of oscillatory activity in the theta band during a VSTM task, we demonstrate that increasing memory load to capacity induces a parametric shift in theta frequency band during the delay period, from 4 to 8 Hz, in a right fronto-parietal network. Critically, we show that an individual's VSTM capacity is proportional to that parametric shift. Thus, the adherence of cortical neuronal oscillations to a fundamental principle of efficient information transfer appears to underlie the limited nature of visual representation in short-term memory.
✍ Moran, R.J.; Strange, B.A.; Campo, P.; Dolan, R.J. πŸ“‚ Article πŸ“… 2009 πŸ› Elsevier Science 🌐 English βš– 142 KB