Randomness of Functional Connectivity Networks for Working Memory and Episodic Memory

Sengupta, Pallabi (2013) Randomness of Functional Connectivity Networks for Working Memory and Episodic Memory. Masters thesis, Indian Institute of Science Education and Research Kolkata.

PDF (MS Dissertation of Pallabi Sengupta (08MS61)) Pallabi_Sengupta-08Ms61-MSThesis.pdf - Submitted Version Restricted to Repository staff only Download (661kB)

Abstract

The aim of the study was to determine the increment in randomness of the functional connectivity network for working memory and episodic memory with respect to age. Even though the concept of entropy as a measure of randomness dates long back to nineteenth century, with the development of statistical mechanics; calculation of entropy of a network was used recently by Manke et al (2005) [12]. The normalization of entropy was required for a proper indication of randomness of a network, as we found that the entropy increases with number of vertices and edges. The requirement of the calculation of randomness comes from the fact that previous studies by our group (Math�aus, Schmidt, Demirakca, Diener, Banerjee & Schulze (2012) [14]) showed that small-worldness of functional connectivity network, which gives implication of the extent of segregation of the network into modules and integration of these modules, is much lower for the 'old-age' group than that of the 'younger' ones. Moreover, the average shortest path length is observed to have decreased and the transitivity, which gives an indication of network cluster, to have increased in the 'old-age' group. After the determination of be�tting normalization of randomness of a network, increment in randomness is observed with increment in age, especially for the functional connectivity network for working memory.

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