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Ipsilateral cortical activation during finger sequences of increasing complexity: representation of movement difficulty or memory load?

✍ Scribed by Friedhelm Hummel; Rolf Kirsammer; Christian Gerloff

Book ID: 119606390
Publisher: Elsevier Science
Year: 2003
Tongue: English
Weight: 414 KB
Volume: 114
Category: Article
ISSN: 1388-2457
DOI: 10.1016/s1388-2457(02)00417-0

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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.

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