Assessing the Computational Capacity of Functionally-Defined Networks Anthony Randal McIntosh The Rotman Research Institute Rolf Kötter C. &. O. Vogt Brain Research Institute Computational Systems Neuroscience Group

Network Participation Indices (NPI) & Regional Maps Density –Proportion of existing connections (afferent and efferent) relative to the number of all potential connections –1.0 high density Transmission –Proportion of outputs relative to the number of existing inputs and outputs –Outdegree & indegree in graph theory –T >0.5 more efferents, T<0.5 more afferents Symmetry –Proportion of reciprocal connections relative to existing reciprocal and unidirectional connections –S >0.5 more reciprocal, S <0.5 more asymmetric Kötter & Stephan, Neural Net, 2003Kötter & Wanke, Phil Trans R Soc B 2005

STRESS=0.092 RM entire matrix

Awareness & Medial Temporal Lobe Functional Connectivity AwareUnaware Seed Behavior Seed Behavior McIntosh, Rajah & Lobaugh, J Neurosci, 2003

Aware STRESS=0.076 CCA CCP CCS M1 PCI PCIP PFCCL PFCORB PFCPOL PFCVL PHC PMCVL S1 TCC TCI TCPOL TCS V1 V2 VACD VACV Transmission Density Symmetry Single Primary Cluster Significant regions show increase in density and transmission: TC V1 (transmission greater) VACv PHC PFCpol (symmetry)

STRESS=0.053 A2 CCP IA PCI PFCCL PFCM PFCORB PFCVL PHC PMCVL TCC TCI TCPOL TCS V1 Transmission Density Symmetry Unaware Two Clusters based on density V1 isolation (no intermediate VA areas) Higher density: PFCm PFCorb PHC Reduced Transmission: PFCvl TCs