As shown in Table 1, PD and HC patients did differ in age, and MMSE scores. PD group had significant higher ages and lower cognitive performance according to the scores in the MMSE compared to HC group (p <0.001). In order to show the possible effects of the age difference and MMSE scores between groups, the demeaned age and MMSE scores were included as covariate in the functional connectivity analysis that suggested special role of pulvinar in PD patients.
Within Group Functional Connectivity
The resting state seed based functional connectivity of the HC and PD groups were computed separately and shown in table 2 and 3 for all seeds. As revealed in tables, all seeds were connected to both cortical and subcortical gray matter structures in the HC group. Furthermore, all seeds had the greatest cluster size with the thalamus in both groups. We also observed that the left and right PuM had the most extensive connectivity among all seeds in the HC group (Table 2-3). In addition, the PD group showed connectivity with fewer brain regions than the HC group (Fig. 1-2).
In the HC group, the right pulvinar seeds showed connectivity to the thalamus, hippocampus, brainstem, cerebellum, and cortical areas, including parietal, temporal, occipital, frontal, insular, cingulate. The left pulvinar seeds showed connectivity to the thalamus, hippocampus, amygdala, cerebellum, and cortical areas, including parietal, temporal, occipital, frontal, cingulate (Table 2-3). The functional connectivity of pulvinar seeds in the PD group were found between the right pulvinar and thalamus, hippocampus, brainstem, cerebellum, cingulate cortex; left pulvinar and thalamus, hippocampus, brainstem, and temporal cortex (Table 2-3).
Between Groups Functional Connectivity
Although there was a significant difference in age between the HC and PD groups (p<0.001), no significant effect of age was found between the two groups for functional connectivity. However, there was a significant effect of MMSE score in connectivity between two groups (Table 4). The analysis revealed the MMSE score related changes in connectivity of the pulvinar subdivisions. In particular, the stronger connectivity was observed in left PuI with bilateral thalamus, PCC, left hippocampus, brainstem; left PuL with the left thalamus; left PuM with bilateral thalamus; right PuI with bilateral thalamus, left hippocampus and brainstem; right PuL with right thalamus; right PuM with bilateral thalamus in HC group than in PD group.
Volumes of the pulvinar nuclei and thalamus
As a quality check, we carried out VBM analysis to segment the anatomical images into the gray matter, white matter, and cerebrospinal fluid. VBM analysis revealed that there were significant differences in the volumes of pulvinar nuclei between HC and patients with PD. Relative to the HC, volume reductions in the PD group were observed in the pulvinar nuclei (p<0.000), as expected. Moreover, we found that right and left thalamus volumes were significantly increased (p<0.000, p=0.003) in HC group compared with the patients. The mean volumes of the pulvinar nuclei and thalamus are shown in Table 5.
Table 1
The demographic features and MMSE scores of participants.
|
HC
|
PD
|
p*
|
N
|
15
|
12
|
NS
|
Age
|
60.26±9.37
|
75.75±10.07
|
0.001
|
Sex (male/female)
|
6 / 9
|
8 /4
|
NS
|
MMSE
|
27.6 ± 1.80
|
19.08±4.16
|
0.000
|
Data presented as mean ± SD. p*<0.001 NS: not significant
Table 2
Clusters of within-group functional connectivity for the right hemisphere seeds.
Region
|
Peak MNI coordinates (x, y, z)
|
Size
|
Size- pFWE
|
t-Max
|
Region
|
Peak MNI coordinates (x, y, z)
|
Size
|
Size- pFWE
|
t-Max
|
Healthy Control
|
|
|
|
|
Parkinson Disease’s
|
|
|
|
|
R-PuA
|
|
|
|
|
|
|
|
|
|
L-R thalamus,
R- insular cortex
|
10 -20 10
|
1673
|
0.000000
|
15.81
|
L- R thalamus
|
12 -22 10
|
626
|
0.000000
|
15.09
|
ACC
|
08 20 32
|
205
|
0.000787
|
7.28
|
R- planum temporale
|
62 -26 12
|
149
|
0.002019
|
8.13
|
R-PuI
|
|
|
|
|
|
|
|
|
|
R-L thalamus,
L-R hippocampus, PCC
|
16 -28 00
|
1136
|
0.000000
|
14.93
|
L-R thalamus, brainstem L-R hippocampus
|
16 -30 00
|
1098
|
0.000000
|
13.83
|
Precuneus cortex
|
02 -64 24
|
524
|
0.000000
|
5.60
|
|
|
|
|
|
L- MFG
|
-30 36 24
|
183
|
0.001604
|
-7.50
|
|
|
|
|
|
R-PuL
|
|
|
|
|
|
|
|
|
|
L-R thalamus
|
12 -22 14
|
1315
|
0.000000
|
11.15
|
L-R thalamus
|
12 -22 14
|
583
|
0.000000
|
16.04
|
Precuneus cortex
|
-02 -42 50
|
246
|
0.000356
|
7.51
|
|
|
|
|
|
R-PuM
|
|
|
|
|
|
|
|
|
|
L-R thalamus, PCC
|
10 -26 08
|
3719
|
0.000000
|
17.65
|
L-R thalamus
|
14 -30 10
|
1559
|
0.000000
|
17.60
|
Brainstem
|
12 -16 -26
|
830
|
0.000000
|
9.55
|
R-fusiform cortex, R-ITG
|
34 -16 -28
|
187
|
0.001904
|
7.60
|
R- SMG
|
54 -34 28
|
459
|
0.000001
|
-9.01
|
|
|
|
|
|
L- insular cortex
|
-36 -04-12
|
458
|
0.000001
|
-9.68
|
|
|
|
|
|
L-R ICC, L-R lingual gyrus
|
06 -64 08
|
395
|
0.000003
|
-7.30
|
|
|
|
|
|
R- L IFG, R-L PreCG
|
42 04 18
|
340
|
0.000015
|
-7.72
|
|
|
|
|
|
L-R cerebellum
|
06 -50 -46
|
312
|
0.000033
|
8.37
|
|
|
|
|
|
R- hippocampus,
R- fusiform cortex
|
36 -14 -24
|
280
|
0.000087
|
9.00
|
|
|
|
|
|
Cingulate cortex
|
-02 -12 38
|
200
|
0.001145
|
6.58
|
|
|
|
|
|
L- MFG
|
-46 02 46
|
187
|
0.001793
|
-6.27
|
|
|
|
|
|
R- PostCG
|
08 -28 72
|
170
|
0.003275
|
8.93
|
|
|
|
|
|
R- SPL, R- angular gyrus
|
42 -48 54
|
158
|
0.005070
|
-6.07
|
|
|
|
|
|
Abbreviations: L, left; R, right; ACC, anterior cingulate cortex; ICC, intracalcarine cortex; IFG, inferior frontal gyrus; ITG, inferior temporal gyrus; MFG, middle frontal gyrus; PCC, posterior cingulate cortex; PreCG, precentral gyrus; PostCG, postcentral gyrus; SMG, supramarginal gyrus; SPL, superior parietal lobule
Table 3
Clusters of within-group functional connectivity for the left hemisphere seeds.
Region
|
Peak MNI coordinates (x, y, z)
|
Size
|
Size- pFWE
|
t-Max
|
Region
|
Peak MNI coordinates (x, y, z)
|
Size
|
Size- pFWE
|
t-Max
|
Healthy Control
|
|
|
|
|
Parkinson Disease’s
|
|
|
|
|
L-PuA
|
|
|
|
|
|
|
|
|
|
L-R thalamus
|
-12 -22 08
|
1189
|
0.000000
|
13.07
|
L-R thalamus
|
-12 -22 12
|
803
|
0.000000
|
14.92
|
L-fusiform cortex, L-ITG,
L-PPHG
|
-34 -32-16
|
255
|
0.000211
|
7.27
|
|
|
|
|
|
PCC, precuneus
|
02 -54 10
|
250
|
0.000247
|
6.68
|
|
|
|
|
|
L-PuI
|
|
|
|
|
|
|
|
|
|
L-R thalamus,
L-R hippocampus
|
-18 -30 00
|
1686
|
0.000000
|
17.44
|
L-R thalamus,
L-R hippocampus,
PCC, brainstem,
L-cerebellum
|
-18 -30 02
|
1547
|
0.000000
|
11.95
|
L- ITG, L- fusiform cortex
|
-46 -48-22
|
139
|
0.007013
|
6.86
|
|
|
|
|
|
L-PuL
|
|
|
|
|
|
|
|
|
|
L-R thalamus
|
-12 -22 14
|
1369
|
0.000000
|
13.95
|
L-R thalamus
|
-14 -24 14
|
665
|
0.000000
|
14.26
|
Precuneus cortex, L-R LOC,
L- SPL
|
14 -76 50
|
571
|
0.000000
|
8.66
|
|
|
|
|
|
FMC
|
-46 44 -16
|
455
|
0.000000
|
-9.71
|
|
|
|
|
|
R- amygdala,
|
14 02 -16
|
150
|
0.004708
|
-6.84
|
|
|
|
|
|
L-PuM
|
|
|
|
|
|
|
|
|
|
L-R thalamus, PCC
|
-12 -30 06
|
3063
|
0.000000
|
18.23
|
L-R thalamus
|
-14 -30 06
|
1712
|
0.000000
|
17.53
|
ACC, R-PreCG,
R-L paracingulate gyrus
|
42 02 44
|
905
|
0.000000
|
-8.77
|
|
|
|
|
|
R-L SMG
|
62 -24 36
|
474
|
0.000000
|
-9.15
|
|
|
|
|
|
Precuneus cortex
|
06 -46 36
|
384
|
0.000003
|
6.87
|
|
|
|
|
|
R- lingual Gyrus, R- ICC
|
10 -86 02
|
338
|
0.000012
|
-8.22
|
|
|
|
|
|
R-MTG, R- fusiform cortex
|
36 -14 -24
|
319
|
0.000022
|
9.87
|
|
|
|
|
|
L- SFG, L-MFG
|
-28 24 52
|
301
|
0.000037
|
10.37
|
|
|
|
|
|
R- LOC
|
10 -64 60
|
281
|
0.000069
|
-6.50
|
|
|
|
|
|
R- cerebellum
|
30 -60 -26
|
178
|
0.002133
|
-13.39
|
|
|
|
|
|
Abbreviations: L, left; R, right; ACC, anterior cingulate cortex; FMC, frontal medial cortex; ICC, intracalcarine cortex; ITG, inferior temporal gyrus; LOC, lateral occipital cortex; MFG, middle frontal gyrus; MTG, middle temporal gyrus; PCC, posterior cingulate cortex; PreCG, precentral gyrus; PPHG, posterior parahippocampal gyrus; SFG, superior frontal gyrus; SMG, supramarginal gyrus; SPL, superior parietal lobule.
Table 4
The effect of MMSE on connectivity in groups. Between-groups functional connectivity differences for HC > PD contrast.
|
MNI Coordinate
|
Region
|
Clusters Size
|
FWE
|
L-PuI
|
14 -30 00
|
L-R thalamus
PCC
L-hippocampus
brainstem
|
529
|
0.000004
|
L-PuL
|
-14 -28 16
|
L- thalamus
|
288
|
0.001083
|
L-PuM
|
-10 -28 08
|
L-R thalamus
|
266
|
0.002346
|
R-PuI
|
-16 -30 00
|
L- thalamus
L-hippocampus
|
290
|
0.000883
|
14 -30 00
|
R-thalamus
brainstem
|
269
|
0.001449
|
R-PuL
|
16 -26 18
|
R-thalamus
|
338
|
0.000406
|
R-PuM
|
-04 -32 14
|
R-L thalamus
|
280
|
0.00194
|
Abbreviations: L, left; R, right, PCC, posterior cingulate cortex
Table 5 Comparisons of pulvinar seeds volumes in patients with Parkinson disease and healthy controls
|
Healthy Controls
|
Parkinson Disease’s
|
Mean Differences (p-value)
|
|
Mean, %
|
SD, %
|
Mean, %
|
SD, %
|
HC > PD
|
R- Pulvinar
|
0.82069
|
0.084392
|
0.62975
|
0.112525
|
**0.000
|
L- Pulvinar
|
0.64909
|
0.067201
|
0.52966
|
0.064898
|
**0.000
|
R-Thalamus
|
4.92291
|
0.281830
|
3.94133
|
0.567563
|
**0.000
|
L-Thalamus
|
4.82235
|
0.276868
|
4.06551
|
0.470424
|
**0.003
|
SD standard deviation, L: left, R: right. *p < 0.05, **p < 0.01.