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A computational study of visual working memory capacity in the presence of saliency effects
BMC Neuroscience volume 12, Article number: P64 (2011)
The study of working memory capacity is of outmost importance in cognitive psychology as working memory is at the basis of general cognitive function. Although the storage capacity limit has been thoroughly studied , its origin still remains a matter of debate. Several neurophysiological studies suggest that items are maintained in working memory through elevated firing activity in cortical neural assemblies that selectively respond to specific stimuli. Accounting for this experimental observation, Edin et al.  proposed a mechanistic explanation of the top-down control of working memory capacity and, based on a mean-field analysis, established an upper boundary to the number of items that can be held in memory. By also making use of a recurrent network model of working memory , we have further investigated the mechanisms underlying working memory capacity while also accounting for the two following experimental observations: 1) visual saliency reduces the number of items that can be held in working memory, and 2) visually salient items are commonly kept in memory in delay match-to-sample tasks at the cost of not keeping as many non-salient items.
A severe limitation in visual working memory capacity arises from the constraints that lateral inhibition imposes to the mnemonic activity during the delay period. However, it is also worth noting that a further limitation to working memory capacity derives from the need that the neural assemblies which have received stimulation reach a sufficiently high level of excitation. In particular, in the presence of visual saliency, the neural assemblies that receive stimulation but are not selective to the salient stimulus are less likely to achieve the elevated firing rates required to be subsequently held in memory.
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Edin F, Klingberg T, Johansson P, McNab F, Tegnér J, Compte A: Mechanism for top-down control of working memory capacity. Proc Natl Acad Sci. 2009, 106 (16): 6802-6807. 10.1073/pnas.0901894106.
Brunel N, Wang XJ: Effects of neuromodulation in a cortical network of object working memory dominated by recurrent inhibition. J Comput Neurosci. 2001, 11: 63-85. 10.1023/A:1011204814320.
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Dempere-Marco, L., Melcher, D.P. & Deco, G. A computational study of visual working memory capacity in the presence of saliency effects. BMC Neurosci 12, P64 (2011) doi:10.1186/1471-2202-12-S1-P64
- Lateral Inhibition
- Work Memory Capacity
- Delay Period
- Firing Activity
- Recurrent Network