Assessing the Computational Capacity Assessing the Computational Capacity of Functionally-Defined Networksof 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, 2003 Kötter & Wanke, Phil Trans R Soc B 2005
A1
A2
CCACCP
CCR
CCS
FEF
IA
IP
M1
PCI
PCIP
PCM
PCS
PFCCL
PFCDLPFCDM
PFCM
PFCORB
PFCPOL
PFCVL
PHCPMCDLPMCM
PMCVL
S1
S2
TCCTCI
TCPOL
TCS
TCV
V1
V2
VACD
VACV
Pulvinar
ThalAM
Transmission
Density
Symmetry
STRESS=0.092
RM entire matrix
Awareness & Medial Temporal Lobe Functional Connectivity
Aware Unaware
See
d
Beh
avio
r
See
d
Beh
avio
r
McIntosh, Rajah & Lobaugh, J Neurosci, 2003
AwareSTRESS=0.076
CCA
CCP
CCS
M1
PCIPCIP
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:TCV1 (transmission greater)VACvPHCPFCpol (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 densityV1 isolation (no intermediate VA areas)
Higher density:PFCmPFCorbPHC
Reduced Transmission:PFCvlTCs