Reconstructions of Information in Visual Spatial Working Memory Degrade with Memory Load

Working memory (WM) enables the maintenance and manipulation of information relevant to behavioral goals. Variability in WM ability is strongly correlated with IQ [1], and WM function is impaired in many neurological and psychiatric disorders [2, 3], suggesting that this system is a core component o...

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Veröffentlicht in:Current biology 2014-09, Vol.24 (18), p.2174-2180
Hauptverfasser: Sprague, Thomas C., Ester, Edward F., Serences, John T.
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Sprache:eng
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Zusammenfassung:Working memory (WM) enables the maintenance and manipulation of information relevant to behavioral goals. Variability in WM ability is strongly correlated with IQ [1], and WM function is impaired in many neurological and psychiatric disorders [2, 3], suggesting that this system is a core component of higher cognition. WM storage is thought to be mediated by patterns of activity in neural populations selective for specific properties (e.g., color, orientation, location, and motion direction) of memoranda [4–13]. Accordingly, many models propose that differences in the amplitude of these population responses should be related to differences in memory performance [14, 15]. Here, we used functional magnetic resonance imaging and an image reconstruction technique based on a spatial encoding model [16] to visualize and quantify population-level memory representations supported by multivoxel patterns of activation within regions of occipital, parietal and frontal cortex while participants precisely remembered the location(s) of zero, one, or two small stimuli. We successfully reconstructed images containing representations of the remembered—but not forgotten—locations within regions of occipital, parietal, and frontal cortex using delay-period activation patterns. Critically, the amplitude of representations of remembered locations and behavioral performance both decreased with increasing memory load. These results suggest that differences in visual WM performance between memory load conditions are mediated by changes in the fidelity of large-scale population response profiles distributed across multiple areas of human cortex. [Display omitted] •We reconstructed images of remembered visual stimuli•We found mnemonic representations in occipital, parietal, and frontal cortex•When multiple items were remembered, target representations decreased in amplitude•Changes in amplitude echoed changes in behavioral performance Working memory is an important component of cognition, enabling information to be maintained and manipulated through time. Sprague et al. reconstruct the contents of spatial working memory from brain activation patterns measured with fMRI to show that when more information is remembered, neural representations of items held in working memory degrade.
ISSN:0960-9822
1879-0445
DOI:10.1016/j.cub.2014.07.066