Differen
ntial Resting-S
State Network Connectivity of Extrastriatte Body Area and Lateral O
Occipital Com
mplex
1
Kaundinya Gopinath1,2, Aman
n Goyal2, Richard Briggs2, and K Saathian3
Deparrtment of Radiolog
gy & Imaging Scieences, Emory Univversity, Atlanta, GA
A, United States, 2D
Department of Raadiology, UT Southhwestern Medical C
Center, Dallas, TX
X,
United
U
States, 3Department of Neurolo
ogy, Emory Univer
ersity, Atlanta, GA,, United States
Introd
duction: A numberr of areas in the hu
uman occipitotemp
poral cortex (OTC) are specialized ffor processing partticular types of sennsory stimuli [1-4]]. These include th
he
lateral occipital complex
x (LOC), an object-selective area; th
he fusiform face area
a
(FFA), a face--selective area; thee parahippocampaal place area (PPA
A), a scene-selectiv
ve
ning resting state fuunctional connectiivity networks of tthese areas will yieeld insights into th
he
area; annd the extrastriate body area (EBA), a body part-selecctive area. Examin
processing of different ty
ypes of stimuli. In this study, fcMRI networks of OTC sub-regions weree delineated with seeed and graph based approaches [5].
ge = 30.9 yrs) weree scanned in a Siem
mens 3T Tim Trioo scanner using a 112-channel array
Methoods: Nineteen right-handed normal subjects (16 male; 3 female; mean ag
receivee-only head coil. Written
W
informed consent
c
was obtain
ned from all particiipants in the proto col approved by thhe local Institutionnal Review Board. In the fcMRI
paradiggm, subjects underrwent an 11-minutte fcMRI scan duriing which they lay
y quietly in the scaanner with their eyyes open. FcMRI scans were acquireed with an axial
whole--brain gradient ech
ho EPI (TR/TE = 2000/24
2
ms, FA = 80°, in-plane resolution = 3.4 mm x 3.4 mm; 40 slicess with thickness 3..5 mm).The fcMR
RI time-series were,
registeered, spatially norm
malized to the MNI template and low
w-pass filtered (0-0
0.1 Hz), followed bby spatial smoothiing with a FWHM
M = 5 mm isotropicc gaussian kernel.
c
of activatioon in EBA, LOC, F
FFA and PPA seenn in appropriate seensory processing
ROI-avveraged time-seriees were obtained frrom 5mm sphericaal seeds placed at centers
studiess [1-4], which serv
ved as reference veectors in cross-corrrelation analysis (C
CCA). Mixed-effeects ANOVA (ROII X Subjects) was performed on z-trransformed CC
maps, tto assess functionaal connectivity nettworks of EBA, LO
OC, FFA and PPA
A, as well as assesss differences in funnctional connectivvity between the 4 regions. The
resultaant statistical param
metric maps were clustered
c
and signiificance of cluster--level activation w
was assessed with M
Monte-Carlo modeeling [6].Graph theory measures
were employed to further probe the networrk structure of each
h OTC sub-region
ns’ functional connnectivity maps. Grraphs for OTC ROIs were formed byy considering areass
(
CC ROI > 0.3;
0 cluster p < 0.0
0001) to respectivee ROIs, resampledd to 6 mm3 voxels aand restricted to grray matter. For eacch ROI, a binary
significcantly connected (average
distancce matrix was consstructed by averaging the individual correlation matricces for all subjects and setting all connnections below thhe threshold averaage CC to 0. The
threshoold was adjusted so that the modularrity, M [5, 7] of thee graph was > 0.3 [7]. Modularities of equivalent randdom graphs [5], Mrandom were also obbtained for
compaarison. Data analyssis was performed with AFNI, FSL and
a Brain Connecttivity toolboxes [5 ].
Resultts & Discussion: EBA
E
exhibited strong functional con
nnectivity (CC > 0.3,
0 cluster-level p < 0.0001) with a number of differeent brain regions. W
When these region
ns
were fu
further examined with
w graph theory based
b
modularity analysis they exhiibited segregation into three modulees (Figure 1; M > 0.3; Mrandom = 0.022): a module (blue
e)
consistting of the defaultt mode network (D
DMN) and limbic regions; a second module (red) morre strongly conneccted with EBA, coonsisting of motorr cortex, Brodmann
area (B
BA) 6 and superio
or temporal gyrus (STG);
(
and a third
d module (yellow)) comprising occippital gyrus, OTC aand medial posterrior parietal cortexx. When modularitty
analysiis was applied to regions
r
strongly connected
c
to LOC (CC > 0.3, clusteer-level p < 0.00011), three modules (M > 0.3; Mrandomm = 0.02) were obttained (Table 1): an
a
OTC aand occipital modu
ule comprising lateral frontal and parietal
p
attention networks
n
and a thhird module consiisting of somatoseensory regions. In the EBA vs. LOC
C
contrasst (Figure 2; Tablee 2), EBA exhibitted significantly (ccluster-level p < 0.05)
0
higher functtional connectivityy with DMN regioons, motor and prremotor cortex, an
nd
middlee occipital gyrus. LOC
L
exhibited sign
nificantly (cluster--level p < 0.05) hig
gher functional connnectivity with latteral frontal, pariettal and somatosensory areas.
The stronger functional connecctivity of EBA with
h DMN is consisteent with studies thhat report a role forr self-referential processing [8] in viisual representation
of bodies. The stronger functional
f
connecttivity of LOC with
h frontoparietal an
nd somatosensory rregions is consisteent with a model oof multisensory obbject representation
n,
onnections [9]. FcMRI networks rev
veal different pathw
ways for body andd object representaation in the brain. G
Graph theory based
engagiing both top-down and bottom-up co
modulaarity analysis reveeals sub-networks within
w
the regions functionally conn
nected to EBA and LOC, representinng their involvemennt in different cognnitive systems.
Figuure 1: Brain region
ns functionally con
nnected to EBA (C
CC > 0.3; p < 0.000
01)
segrregated into 3 mod
dules (2475 nodes). Slice locations in
n MNI co-ordinatees.
Figuree 2: LOC – EBA t--contrast map (p < 0.05). Slice
locatioons in MNI co-orddinates.
ons functionally co
onnected to LOC (CC
(
> 0.3; p < 0.00001; 2061-node ggraph) segregated iinto 3 modules
Table 1: Brain regio
Module 1
<CCLOOC> = 0.41; 957 no
odes
Module 2
<CCLOOC> = 0.41; 344 no
odes
Module 3
<CCLOOC> = 0.37; 760 no
odes
Occip
pital gyrus, OTC, ccerebellum, cuneuus
ons: inferior and su
uperior parietal lobbules (I/SPL), BA
A7, dorsolateral PFC, LOC, BA9, BA
A46
Frontall and parietal regio
Sensory areass: primary (S1), and
a secondary (S2)) somatosensory coortex, BA5, STG aand insula
Table2: LOC vs EBA funcctional connectivitty differences (AN
NOVA t-contrast ccluster-level p < 0.05)
EBA > LOC
LOC > EBA
PCC, LPC,
L
precuneus, medial
m
PFC, ITR, MTG,
M
amygdala, veentrolateral PFC, B
BA 38, cuneus, miiddle occipital gyrrus, EBA, M1, premotor
corttex, cingulate, SMA
A.
Dorsolaterral PFC, inferior frrontal gyrus, lateraal BA6, IPL, SPL aand BA 40, laterall BA7, LOC, S1, S
S2, insula
A et al., Cereb. Cort.,
C
12:1202-121
12, 2002; [2] Orlo
ov T. et al., Neuroon, 68:586-600, 20010; [3] Pitcher D
D., et al., Neuroimaage, 56:2356-2363
3,
Refereences: [1] Amedi A.,
2011; [[4] Epstein R., et al., Cereb. Cort., 17:1680-1693, 200
07; [5] Rubinov M.,
M et al., Neuroim
mage, 52:1059–10669, 2010; [6] Form
man S., Magn. Reson. Med., 33:636
6647, 19995; [7] Newman
n M., et al., Phys. Rev. E, 69:026113-1-15, 2004; [8] Vocks S., et al. C
Cog. Aff. Soc. Behhav. Neurosci., 100:422-429, 2010; [[9] Lacey S., et all.,
Brain T
Topog., 21:269–27
74.
Acknoowledgments: Thiis study was suppo
orted by IDIQ con
ntract VA549-P-00
027, awarded and aadministered by D
Department of Veteerans Affairs Meddical Center, Dallass,
TX, byy DoD grant DAM
MD 17-01-1-0741, by Atlanta VAMC
C, by NIH Grant EY012440,
E
by Deepartment of Radioology, UT Southw
western Med Ctr., D
Dallas, TX, and by
Departtments of Radiolog
gy and Imaging Scciences, and Neurology, Emory Uniiversity, Atlanta, G
GA. The content d oes not necessarilyy reflect the positiion or the policy of
o
the fedderal government or
o the sponsoring agencies,
a
and no official endorsemen
nt should be inferrred.
Proc. Intl. Soc. Mag. Reson. Med. 20 (2012)
2115