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Neuroimage. 2015 Jul 1;114:320-7. doi: 10.1016/j.neuroimage.2015.04.001. Epub 2015 Apr 9.

Context-specific differences in fronto-parieto-occipital effective connectivity during short-term memory maintenance.

Author information

1
Neuroscience Training Program and Medical Scientist Training Program, University of Wisconsin-Madison, 7225 Medical Sciences Center, 1300 University Avenue, Madison, WI 57306, USA. Electronic address: bkundu@wisc.edu.
2
Department of Electrical and Computer Engineering, University of Wisconsin-Madison, 3611 Engineering Hall, 1415 Engineering Drive, Madison, WI 53706, USA.
3
Neuroscience Training Program and Medical Scientist Training Program, University of Wisconsin-Madison, 7225 Medical Sciences Center, 1300 University Avenue, Madison, WI 57306, USA; Department of Psychology, University of Wisconsin-Madison, 1202 West Johnson Street, Madison, WI 53706, USA.

Abstract

Although visual short-term memory (VSTM) performance has been hypothesized to rely on two distinct mechanisms, capacity and filtering, the two have not been dissociated using network-level causality measures. Here, we hypothesized that behavioral tasks challenging capacity or distraction filtering would both engage a common network of areas, namely dorsolateral prefrontal cortex (dlPFC), superior parietal lobule (SPL), and occipital cortex, but would do so according to dissociable patterns of effective connectivity. We tested this by estimating directed connectivity between areas using conditional Granger causality (cGC). Consistent with our prediction, the results indicated that increasing mnemonic load (capacity) increased the top-down drive from dlPFC to SPL, and cGC in the alpha (8-14Hz) frequency range was a predominant component of this effect. The presence of distraction during encoding (filtering), in contrast, was associated with increased top-down drive from dlPFC to occipital cortices directly and from SPL to occipital cortices directly, in both cases in the beta (15-25Hz) range. Thus, although a common anatomical network may serve VSTM in different contexts, it does so via specific functions that are carried out within distinct, dynamically configured frequency channels.

KEYWORDS:

Attention; Effective connectivity; Electroencephalogram; Granger causality; Multivariate autoregressive models; Short-term memory

PMID:
25863155
PMCID:
PMC4446161
DOI:
10.1016/j.neuroimage.2015.04.001
[Indexed for MEDLINE]
Free PMC Article

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