FIGURE 3. (a) The GLM [successful trials >
failed trials] contrast in the second stage of feedback reveals
activated clusters, such as the rPG. (b) The right Sub-gyral
was found correlated with the individual reciprocity index in the
[successful trials > failed trials] contrast. The other
two indices (greed and total reward) were not shown correlated with any
brain regions. (c) The PPI results showed more negative
functional connectivity in the MNS (such as the rPG, the left IPL, and
the bilateral IFG,) with the rTPJseed in the successful
reciprocity trials. (d) The bar graph shows the beta values
extracted from some of the regions shown in (d) for
illustration purposes only. These regions are negatively correlated with
the seed region, the rTPJ [from left to the right:
rTPJseed (M = 0.13, SD = 1.07), rPG
(M = -3.29, SD = 0.51), left IPL (M = -2.98,SD = 0.38), and left IFG -3 (M = -3.15, SD =
0.43)]. (e) The rTPJseed-rPG, -rAG, and -rIPL
connectivities, correlated with individual total reward indicates that
one’s rTPJ (thinking of others) activity increases, with the depressed
activity of the right PG for coordinated action, and the right IPL and
right AG for relating themselves and detecting incongruence, in the
successful reciprocity trials. See further detailed interpretation in
Discussion. (f) The scatter plot shows the correlations between
the total reward and one of the three ROIs (the right IPL chosen for
illustration purposes; See the other two in Supplementary Figure S3)
found via PPI. The three types of participants are: reciprocal (red),
dominant (green), and submissive (blue). The bars on the x axle show the
mean total reward of the three types: reciprocal (NT$ 307.82), dominant
(NT$ 274), and submissive (NT$ 247.28). The scatter plot suggests the
reciprocal individuals (in red) with the most reward
(reciprocal-dominant, p = 0.014; reciprocal-submissive, p< 0.001) and negative connectivity between the
rTPJseed and the right IPL identified from PPI.
rTPJseed-to-whole brain frequency-domain
coherence
Comparisons among various pairing combinations
The rTPJseed-whole brain interpersonal coherence of the
WIPs in the second stage feedback time is shown in the Supplementary
Table S6. Brain regions show significant coherence with the
rTPJseed during the event of feedback time under the
cluster k-threshold of 40 voxels and the applied map threshold of 0.215.
Furthermore, we compared the 36th frequency bin with the rest, excluding
the first 3 bins, and the 35th/the 37th; the peak of 36th bin is higher
than the rest by 1.5 of the standard errors. The ROIs with significant
coherence with the rTPJseed are the rTPJ and among
others. In the WNPs, the rTPJseed are significantly
coupled with the rSTG and others under the cluster k-threshold of 40
voxels and the applied map threshold of 0.215 (see Supplementary Table
S7). Also the peak of the 36th frequency bin is higher than the rest by
1.5 standard errors.
To further investigate inter-regional couplings, Figure 4 shows the
coherence spectra between rTPJseed-rTPJp(posterior right TPJ) in the WIPs pairs (Figure 4a) and
rTPJseed-rSTG in the WNPs (Figure 4b). The independent
two-sample t-tests are applied among every possible pair at the 36th
frequency bin. The rTPJseed-rTPJpcoherence value of the WIPs is stronger than those of the WNPs and BPPs
(all ps < 0.001). The rTPJseed-rSTG coherence
value of the WNPs (in yellow) is stronger than those of the WIPs
(p < 0.016) and BPPs (p < 0.001).
We ran the same analyses and applied the same peak threshold (the 36th
frequency bin is higher than the rest by 1.5 standard errors) on the
first feedback (in the planning stage) to compare with the results of
the second feedback stage in coherence. Brain regions show significant
coherence with the rTPJseed during the event of first
feedback time under the cluster k-threshold of 40 voxels and the applied
map threshold of 0.225. Bilateral Lingual Gyri, the left PG, and the
right Precuneus are identified in the WIPs. In the WNPs, the bilateral
Lingual Gyri were found coupling with the rTPJseedduring the event of first feedback time under the cluster k-threshold of
40 voxels and the applied map threshold of 0.22 (see Figure 4c and
Supplementary Table S8-9).
As the interacting pairs had real interactions with each other in the
same group, we calculated the three neural differences in coherence when
1) reciprocal people interacted with reciprocal partners and 2) with
non-reciprocal ones (the dominant and submissive types). Furthermore, we
calculated the coherence values among 3) the non-reciprocal pairs. After
applying the stringent threshold (the peak of the designated frequency
bin, the 36th, should be higher than the rest by 1.5
standard errors), we found the left TPJ and right IFG coupled with the
rTPJ among the reciprocal pairs (under the cluster k-threshold of 40
voxels and the applied map threshold of 0.228). When the reciprocal
individuals interacted with the non-reciprocal partners, no coupling was
found with the rTPJ. As for the non-reciprocal pairs, their left IFG and
the right amygdala were in sync with the rTPJ (under the cluster
k-threshold of 40 voxels and the applied map threshold of 0.226). (See
Figure 4d-e and the Supplementary Table S10-11)
To examine the brain-behavior relationship, we calculated the
correlation between the coherence values of the regions found coupled
with the rTPJ in the WIP. No significant results were shown (see the
Supplementary Table S12).