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Dynamic Causal Modeling (DCM) neural network. The amygdala (AMY) and the ventral anterior cingulate cortex (ACC) are the regions of interest (ROIs). The faces (regardless of the emotion) were entered as driving input (DCM matrix C values) directly in both the ROIs according with electrophysiological data. The intrinsic connectivity between ROIs (DCM matrix A values) was modelled as bidirectional (see DCM methods section for further details). ‘ Angry faces ’ was used as bilinear modulator (DCM matrix B values) of connectivity in both pathways (from ventral ACC to AMY and from AMY to ventral ACC). 

Dynamic Causal Modeling (DCM) neural network. The amygdala (AMY) and the ventral anterior cingulate cortex (ACC) are the regions of interest (ROIs). The faces (regardless of the emotion) were entered as driving input (DCM matrix C values) directly in both the ROIs according with electrophysiological data. The intrinsic connectivity between ROIs (DCM matrix A values) was modelled as bidirectional (see DCM methods section for further details). ‘ Angry faces ’ was used as bilinear modulator (DCM matrix B values) of connectivity in both pathways (from ventral ACC to AMY and from AMY to ventral ACC). 

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For some people facial expressions of aggression are intimidating, for others they are perceived as provocative, evoking an aggressive response. Identifying the key neurobiological factors that underlie this variation is fundamental to our understanding of aggressive behaviour. The amygdala and the ventral anterior cingulate cortex (ACC) have been...

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... intrinsic connections (connectivity regardless the main effect of the task, DCM Bilinear matrix A value; see Fig. 2) were modelled as bidirectional in accord with anatomical evidence showing that the ventral ACC projects to the amygdala and vice versa ( Aggleton et al., 1980;Amaral and Price, 1984;Ghashghaei et al., 2007;McDonald and Mascagni, ...
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... modulation by the emotion of faces was included as a bilinear effect expressing the contextual moderator (i.e. anger versus neutral context; DCM Bilinear matrix B value; see Fig. 2). A significant effect of the bilinear variable on connectivity indicates a PPI ( Friston et al., ...
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... presentation of faces regardless of the emotional expres- sion) were 'injected' into different parts of the network (Supplemen- tary Fig. 1). This 'injection' determines the origin of perturbation of the network, from which other points in the network will be activated according to the pattern of connectivity. For the first "parallel" model ( Fig. 2), face driving inputs (i.e., all faces, regardless of emotional expressions) were 'injected' into both amygdala and the ventral ACC. This was considered the more neurobiologically plausible model according to electrophysiological literature in animals ( Leonard et al., 1985;Rolls, 2007) and humans (Eimer and Holmes, 2007;Eimer et al., ...
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... every participant we found very strong evidence (see DCM results and Supplementary Fig. 2), in favour of the "parallel" model 1. Therefore using this model we further analyzed the impact of the driving input (all faces) (DCM matrix C value: effect of faces regardless of the expression) on both ROI activities, the intrinsic connectivity between the ROIs (DCM matrix A value: connectivity regardless the main effect of the task), and the modulatory effect by emotion (DCM matrix B value: angry vs. neutral context) on specific bidirectional intrinsic connections (from amygdala to the ventral ACC and from the ventral ACC to amygdala) in each participant at a fixed-effects level. ...
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... the Bayesian model selection procedure ( Penny et al., 2004), we found strong evidence that the parallel model 1 was associated with the highest probability to explain the data (see Supplementary Fig. 2). Therefore we used model 1 to test for modulatory influence of anger (vs. ...
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... intrinsic connections (connectivity regardless the main effect of the task, DCM Bilinear matrix A value; see Fig. 2) were modelled as bidirectional in accord with anatomical evidence showing that the ventral ACC projects to the amygdala and vice versa (Aggleton et al., 1980;Amaral and Price, 1984;Ghashghaei et al., 2007;McDonald and Mascagni, ...
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... modulation by the emotion of faces was included as a bilinear effect expressing the contextual moderator (i.e. anger versus neutral context; DCM Bilinear matrix B value; see Fig. 2). A significant effect of the bilinear variable on connectivity indicates a PPI ( Friston et al., ...
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... (i.e. presentation of faces regardless of the emotional expression) were 'injected' into different parts of the network (Supplementary Fig. 1). This 'injection' determines the origin of perturbation of the network, from which other points in the network will be activated according to the pattern of connectivity. For the first "parallel" model ( Fig. 2), face driving inputs (i.e., all faces, regardless of emotional expressions) were 'injected' into both amygdala and the ventral ACC. This was considered the more neurobiologically plausible model according to electrophysiological literature in animals ( Leonard et al., 1985;Rolls, 2007) and humans (Eimer and Holmes, 2007;Eimer et al., ...
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... every participant we found very strong evidence (see DCM results and Supplementary Fig. 2), in favour of the "parallel" model 1. Therefore using this model we further analyzed the impact of the driving input (all faces) (DCM matrix C value: effect of faces regardless of the expression) on both ROI activities, the intrinsic connectivity between the ROIs (DCM matrix A value: connectivity regardless the main effect of the task), and the modulatory effect by emotion (DCM matrix B value: angry vs. neutral context) on specific bidirectional intrinsic connections (from amygdala to the ventral ACC and from the ventral ACC to amygdala) in each participant at a fixed-effects level. ...
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... the Bayesian model selection procedure (Penny et al., 2004), we found strong evidence that the parallel model 1 was associated with the highest probability to explain the data (see Supplementary Fig. 2). Therefore we used model 1 to test for modulatory influence of anger (vs. ...
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... see Supplementary Table 1). Again, the time-series for each participant was computed by using the fi rst eigenvariate from all voxels ’ time series in this common left amygdala ROI. Regardless of the approach used to extract the time-series in the source region we obtained highly consistent results (see PPI GLM results section). The BOLD time series for each participant was deconvolved to estimate a ‘ neuronal time series ’ for this region (Gitelman et al., 2003). The psycho-physiological interaction term (PPI regressor) was calculated as the element-by-element product of the left amygdala neuronal time series and a vector coding for the main effect of task (1 for angry faces, − 1 for neutral faces, and 0 for null events). This product was re-convolved by the canonical hemodynamic response function (hrf). The model also included the main effects of task convolved by the hrf, and the movement regressors as effects of no interest. Participant speci fi c PPI models were run, and contrast images generated for positive and negative PPIs. The identi fi ed regions have greater or lesser connectivity with the source region according the context of angry vs. neutral face presentation. The 21 contrast images were entered into second level GLM analyses for contrasts of interest, and SPM-maps generated using Gaussian Random Field theory to make statistical inferences (Friston et al., 1995). To test regions with changes in connectivity with the source region following angry vs . neutral faces context in the whole sample (regardless of any personality dimension) we used a one sample t test. To identify regions for which the changes in connectivity with the source region (following angry vs. neutral faces context) were correlated with the individual variation in reward – drive score, we employed a regression model within SPM. Using distinct regression models, we also explored any correlations with the fun seeking and reward responsiveness subscales, although these dimensions have been associated with measures of aggression to a lesser extent (Carver, 2004; Putman et al., 2004). Moreover, as the neural response to angry faces has also been found to be in fl uenced by anxiety and depression (Ewbank et al., submitted; Leyman et al., 2007; Phan et al., 2006), we investigated any potential effect of the participants' STAI (state and trait anxiety) scores, FNE (fear negative evaluation) scores and CES-D (depression) scores on the connectivity between the amygdala and other potential brain ‘ target ’ regions (regression models). Two approaches to statistically threshold maps were applied. First, for small volume corrections (svc) within a priori regions of interest (ROI), the threshold was set at p b .05 Family Wise Error (Worsley et al., 1996). For the effect of reward – drive, we de fi ned a 15-mm sphere in the ventral ACC ROI using as center the local maxima derived from our previous study ( x − 15, y 36, z − 12) (Beaver et al., 2008). For the effect of anxiety the ROIs comprised the dorsal ACC (MNI local maxima: x − 2, y 12, z 40) and the ventrolateral prefrontal cortex (VLPFC) (MNI local maxima: x − 36, y 16, z − 6), de fi ned from previous work (Bishop et al., 2004; Bishop et al., 2007). Second, to explore other possible regions which were not predicted, a threshold of p b .001, uncorrected was used. To understand further the effective connectivity between the amygdala and the ventral ACC (the two regions showing a higher order interaction with the reward – drive personality, see the PPI GLM results section) we used dynamic causal modelling (DCM) (Friston et al., 2003). DCM enables an alternative method of analysis of psychophysiological interactions within a hypothesis driven anatomical model. More speci fi cally, the DCM explains regional effects in terms of changing patterns of connectivity amongst regions according to experimentally induced contextual modulation of connection strengths. The principal advantage of DCM over the GLM implementa- tion of PPI analysis is the ability to make inferences about the directionality of causal connections. The DCM anatomical model was built from speci fi c hypotheses about the amygdala and the ventral ACC as key neural structures for the processing and recognition of emotional faces (Adolphs et al., 1999; Broks et al., 1998; Calder et al., 2001; Hornak et al., 2003). A 10 mm sphere ROI was created in the left amygdala by using the local maximum for each participant that was the nearest voxel to the activation peak in the left amygdala de fi ned by the whole group cluster (Supplementary Table 1). For the ventral ACC, a 15 mm sphere ROI was de fi ned using the local maxima for each subject that was the nearest voxel to the activation peak identi fi ed by the PPI analysis (see Results section, Analysis of effective connectivity 1: PPIs in the General Linear Model). The intrinsic connections (connectivity regardless the main effect of the task, DCM Bilinear matrix A value; see Fig. 2) were modelled as bidirectional in accord with anatomical evidence showing that the ventral ACC projects to the amygdala and vice versa (Aggleton et al., 1980; Amaral and Price, 1984; Ghashghaei et al., 2007; McDonald and Mascagni, 1996). The modulation by the emotion of faces was included as a bilinear effect expressing the contextual moderator (i.e. anger versus neutral context; DCM Bilinear matrix B value; see Fig. 2). A signi fi cant effect of the bilinear variable on connectivity indicates a PPI (Friston et al., 2003). We fi rst tested three different DCM models in which the driving inputs (i.e. presentation of faces regardless of the emotional expression) were ‘ injected ’ into different parts of the network (Supplementary Fig. 1). This ‘ injection ’ determines the origin of perturbation of the network, from which other points in the network will be activated according to the pattern of connectivity. For the fi rst “ parallel ” model (Fig. 2), face driving inputs (i.e., all faces, regardless of emotional expressions) were ‘ injected ’ into both amygdala and the ventral ACC. This was considered the more neurobiologically plausible model according to electrophysiological literature in animals (Leonard et al., 1985; Rolls, 2007) and humans (Eimer and Holmes, 2007; Eimer et al., 2003; Kawasaki et al., 2001; Oya et al., 2002) suggesting that the amygdala and ACC respond very quickly and within approximately the same time-scale window ( ∼ 110 – 220 ms) to faces. The two last “ serial ” models differ from the fi rst one with respect to where the driving inputs were injected: only in the amygdala (model 2) or only in the ventral ACC (model 3). When comparing all models using Bayesian model selection implemented within SPM5 software we assumed that all of them were equally likely a priori (Penny et al., 2004). We used the selection procedure which estimates the probability of each model given the data using Akaike's information criterion (AIC) and Bayesian's information criterion (BIC) approximations to each model's log-evidence or marginal likelihood (Penny et al., 2004). For every participant we found very strong evidence (see DCM results and Supplementary Fig. 2), in favour of the “ parallel ” model 1. Therefore using this model we further analyzed the impact of the driving input (all faces) (DCM matrix C value: effect of faces regardless of the expression) on both ROI activities, the intrinsic connectivity between the ROIs (DCM matrix A value: connectivity regardless the main effect of the task), and the modulatory effect by emotion (DCM matrix B value: angry vs. neutral context) on speci fi c bidirectional intrinsic connections (from amygdala to the ventral ACC and from the ventral ACC to amygdala) in each participant at a fi xed-effects level. One sample t tests were performed on the A-, B- and C-DCM matrix values to enable inference about the whole group (irrespective of any personality scores). Finally, individual B-, and C-DCM matrix values were entered into simple regression models with reward – drive, STAI (state or trait) anxiety, FNE (fear negative evaluation), and CES-D (depression) scores as main regressors in order to identify any speci fi c modulation by the reward-drive personality, anxiety or depression. The scores on the BAS/BIS subscales, on the Spielberger State and Trait anxiety (STAI), on the Fear of Negative Evaluation scale (FNE-Brief), and on the Center for Epidemiologic Studies Depression Scale (CES-D) were as follows: BAS reward-drive, range 6 to14 (0.5 – 80 percentile of the normal population), mean = 10.09, SD = 2.02; BAS- reward responsiveness, range 12 to 20 (0.4 – 87 percentile), mean = 16.66, SD = 1.85; BAS-fun seeking, range 7 to15 (0.8 – 87 percentile), mean = 11.66, SD = 2.29; BIS, range 17 to 28 (14 – 98 percentile), mean = 21.71, SD = 3.54; State anxiety, range 20 to 43 (1.7 – 94 percentile), mean = 30.71, SD = 6.76; Trait anxiety, range 21 to 52 (2.5 – 99 percentile), mean = 36.52, SD = 8.39; FNE range 0 to 42 (0 – 94 percentile), mean = 20.45, SD = 12.73; CES-D, range 1 to 24 (17 – 96 percentile), mean = 11, SD = 6.20. We found a borderline negative correlation between the reward – drive and BIS measures ( r = − .40, p = .06). Thus, to exclude any contribution from BIS scores, they were included as a covariate of no interest in the general linear model (GLM). Across the whole group, reaction times (RT) during the gender decision task were longer for angry (mean RT = 717 ms, SD = 88) than for neutral face trials (mean RT = 696 ms; SD = 74; t (20) = 2.46, p b .02). The difference in RT between angry and neutral face trials correlated negatively with reward – drive scores ( r = − .51, p b .02), re fl ecting faster gender categorization of angry faces with increasing reward – drive. This accords with previous research showing increased attention to angry faces in high reward – drive individuals (Putman et al., 2004). Again, to exclude any confounding effect of ...
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... series ’ for this region (Gitelman et al., 2003). The psycho-physiological interaction term (PPI regressor) was calculated as the element-by-element product of the left amygdala neuronal time series and a vector coding for the main effect of task (1 for angry faces, − 1 for neutral faces, and 0 for null events). This product was re-convolved by the canonical hemodynamic response function (hrf). The model also included the main effects of task convolved by the hrf, and the movement regressors as effects of no interest. Participant speci fi c PPI models were run, and contrast images generated for positive and negative PPIs. The identi fi ed regions have greater or lesser connectivity with the source region according the context of angry vs. neutral face presentation. The 21 contrast images were entered into second level GLM analyses for contrasts of interest, and SPM-maps generated using Gaussian Random Field theory to make statistical inferences (Friston et al., 1995). To test regions with changes in connectivity with the source region following angry vs . neutral faces context in the whole sample (regardless of any personality dimension) we used a one sample t test. To identify regions for which the changes in connectivity with the source region (following angry vs. neutral faces context) were correlated with the individual variation in reward – drive score, we employed a regression model within SPM. Using distinct regression models, we also explored any correlations with the fun seeking and reward responsiveness subscales, although these dimensions have been associated with measures of aggression to a lesser extent (Carver, 2004; Putman et al., 2004). Moreover, as the neural response to angry faces has also been found to be in fl uenced by anxiety and depression (Ewbank et al., submitted; Leyman et al., 2007; Phan et al., 2006), we investigated any potential effect of the participants' STAI (state and trait anxiety) scores, FNE (fear negative evaluation) scores and CES-D (depression) scores on the connectivity between the amygdala and other potential brain ‘ target ’ regions (regression models). Two approaches to statistically threshold maps were applied. First, for small volume corrections (svc) within a priori regions of interest (ROI), the threshold was set at p b .05 Family Wise Error (Worsley et al., 1996). For the effect of reward – drive, we de fi ned a 15-mm sphere in the ventral ACC ROI using as center the local maxima derived from our previous study ( x − 15, y 36, z − 12) (Beaver et al., 2008). For the effect of anxiety the ROIs comprised the dorsal ACC (MNI local maxima: x − 2, y 12, z 40) and the ventrolateral prefrontal cortex (VLPFC) (MNI local maxima: x − 36, y 16, z − 6), de fi ned from previous work (Bishop et al., 2004; Bishop et al., 2007). Second, to explore other possible regions which were not predicted, a threshold of p b .001, uncorrected was used. To understand further the effective connectivity between the amygdala and the ventral ACC (the two regions showing a higher order interaction with the reward – drive personality, see the PPI GLM results section) we used dynamic causal modelling (DCM) (Friston et al., 2003). DCM enables an alternative method of analysis of psychophysiological interactions within a hypothesis driven anatomical model. More speci fi cally, the DCM explains regional effects in terms of changing patterns of connectivity amongst regions according to experimentally induced contextual modulation of connection strengths. The principal advantage of DCM over the GLM implementa- tion of PPI analysis is the ability to make inferences about the directionality of causal connections. The DCM anatomical model was built from speci fi c hypotheses about the amygdala and the ventral ACC as key neural structures for the processing and recognition of emotional faces (Adolphs et al., 1999; Broks et al., 1998; Calder et al., 2001; Hornak et al., 2003). A 10 mm sphere ROI was created in the left amygdala by using the local maximum for each participant that was the nearest voxel to the activation peak in the left amygdala de fi ned by the whole group cluster (Supplementary Table 1). For the ventral ACC, a 15 mm sphere ROI was de fi ned using the local maxima for each subject that was the nearest voxel to the activation peak identi fi ed by the PPI analysis (see Results section, Analysis of effective connectivity 1: PPIs in the General Linear Model). The intrinsic connections (connectivity regardless the main effect of the task, DCM Bilinear matrix A value; see Fig. 2) were modelled as bidirectional in accord with anatomical evidence showing that the ventral ACC projects to the amygdala and vice versa (Aggleton et al., 1980; Amaral and Price, 1984; Ghashghaei et al., 2007; McDonald and Mascagni, 1996). The modulation by the emotion of faces was included as a bilinear effect expressing the contextual moderator (i.e. anger versus neutral context; DCM Bilinear matrix B value; see Fig. 2). A signi fi cant effect of the bilinear variable on connectivity indicates a PPI (Friston et al., 2003). We fi rst tested three different DCM models in which the driving inputs (i.e. presentation of faces regardless of the emotional expression) were ‘ injected ’ into different parts of the network (Supplementary Fig. 1). This ‘ injection ’ determines the origin of perturbation of the network, from which other points in the network will be activated according to the pattern of connectivity. For the fi rst “ parallel ” model (Fig. 2), face driving inputs (i.e., all faces, regardless of emotional expressions) were ‘ injected ’ into both amygdala and the ventral ACC. This was considered the more neurobiologically plausible model according to electrophysiological literature in animals (Leonard et al., 1985; Rolls, 2007) and humans (Eimer and Holmes, 2007; Eimer et al., 2003; Kawasaki et al., 2001; Oya et al., 2002) suggesting that the amygdala and ACC respond very quickly and within approximately the same time-scale window ( ∼ 110 – 220 ms) to faces. The two last “ serial ” models differ from the fi rst one with respect to where the driving inputs were injected: only in the amygdala (model 2) or only in the ventral ACC (model 3). When comparing all models using Bayesian model selection implemented within SPM5 software we assumed that all of them were equally likely a priori (Penny et al., 2004). We used the selection procedure which estimates the probability of each model given the data using Akaike's information criterion (AIC) and Bayesian's information criterion (BIC) approximations to each model's log-evidence or marginal likelihood (Penny et al., 2004). For every participant we found very strong evidence (see DCM results and Supplementary Fig. 2), in favour of the “ parallel ” model 1. Therefore using this model we further analyzed the impact of the driving input (all faces) (DCM matrix C value: effect of faces regardless of the expression) on both ROI activities, the intrinsic connectivity between the ROIs (DCM matrix A value: connectivity regardless the main effect of the task), and the modulatory effect by emotion (DCM matrix B value: angry vs. neutral context) on speci fi c bidirectional intrinsic connections (from amygdala to the ventral ACC and from the ventral ACC to amygdala) in each participant at a fi xed-effects level. One sample t tests were performed on the A-, B- and C-DCM matrix values to enable inference about the whole group (irrespective of any personality scores). Finally, individual B-, and C-DCM matrix values were entered into simple regression models with reward – drive, STAI (state or trait) anxiety, FNE (fear negative evaluation), and CES-D (depression) scores as main regressors in order to identify any speci fi c modulation by the reward-drive personality, anxiety or depression. The scores on the BAS/BIS subscales, on the Spielberger State and Trait anxiety (STAI), on the Fear of Negative Evaluation scale (FNE-Brief), and on the Center for Epidemiologic Studies Depression Scale (CES-D) were as follows: BAS reward-drive, range 6 to14 (0.5 – 80 percentile of the normal population), mean = 10.09, SD = 2.02; BAS- reward responsiveness, range 12 to 20 (0.4 – 87 percentile), mean = 16.66, SD = 1.85; BAS-fun seeking, range 7 to15 (0.8 – 87 percentile), mean = 11.66, SD = 2.29; BIS, range 17 to 28 (14 – 98 percentile), mean = 21.71, SD = 3.54; State anxiety, range 20 to 43 (1.7 – 94 percentile), mean = 30.71, SD = 6.76; Trait anxiety, range 21 to 52 (2.5 – 99 percentile), mean = 36.52, SD = 8.39; FNE range 0 to 42 (0 – 94 percentile), mean = 20.45, SD = 12.73; CES-D, range 1 to 24 (17 – 96 percentile), mean = 11, SD = 6.20. We found a borderline negative correlation between the reward – drive and BIS measures ( r = − .40, p = .06). Thus, to exclude any contribution from BIS scores, they were included as a covariate of no interest in the general linear model (GLM). Across the whole group, reaction times (RT) during the gender decision task were longer for angry (mean RT = 717 ms, SD = 88) than for neutral face trials (mean RT = 696 ms; SD = 74; t (20) = 2.46, p b .02). The difference in RT between angry and neutral face trials correlated negatively with reward – drive scores ( r = − .51, p b .02), re fl ecting faster gender categorization of angry faces with increasing reward – drive. This accords with previous research showing increased attention to angry faces in high reward – drive individuals (Putman et al., 2004). Again, to exclude any confounding effect of the response time, the differences in RT between angry and neutral faces trials were factored out in the PPI GLM model. There were no correlations between differences in RT and other BAS/BIS subscales, measures of anxiety, or depression scores ( r s b .23, p s N .15). In addition, task accuracy was consistently high across participants (mean accuracy = 94.5%, SD = 2.39) with no statistically signi fi cant correlations ...
Context 13
... speci fi c PPI models were run, and contrast images generated for positive and negative PPIs. The identi fi ed regions have greater or lesser connectivity with the source region according the context of angry vs. neutral face presentation. The 21 contrast images were entered into second level GLM analyses for contrasts of interest, and SPM-maps generated using Gaussian Random Field theory to make statistical inferences (Friston et al., 1995). To test regions with changes in connectivity with the source region following angry vs . neutral faces context in the whole sample (regardless of any personality dimension) we used a one sample t test. To identify regions for which the changes in connectivity with the source region (following angry vs. neutral faces context) were correlated with the individual variation in reward – drive score, we employed a regression model within SPM. Using distinct regression models, we also explored any correlations with the fun seeking and reward responsiveness subscales, although these dimensions have been associated with measures of aggression to a lesser extent (Carver, 2004; Putman et al., 2004). Moreover, as the neural response to angry faces has also been found to be in fl uenced by anxiety and depression (Ewbank et al., submitted; Leyman et al., 2007; Phan et al., 2006), we investigated any potential effect of the participants' STAI (state and trait anxiety) scores, FNE (fear negative evaluation) scores and CES-D (depression) scores on the connectivity between the amygdala and other potential brain ‘ target ’ regions (regression models). Two approaches to statistically threshold maps were applied. First, for small volume corrections (svc) within a priori regions of interest (ROI), the threshold was set at p b .05 Family Wise Error (Worsley et al., 1996). For the effect of reward – drive, we de fi ned a 15-mm sphere in the ventral ACC ROI using as center the local maxima derived from our previous study ( x − 15, y 36, z − 12) (Beaver et al., 2008). For the effect of anxiety the ROIs comprised the dorsal ACC (MNI local maxima: x − 2, y 12, z 40) and the ventrolateral prefrontal cortex (VLPFC) (MNI local maxima: x − 36, y 16, z − 6), de fi ned from previous work (Bishop et al., 2004; Bishop et al., 2007). Second, to explore other possible regions which were not predicted, a threshold of p b .001, uncorrected was used. To understand further the effective connectivity between the amygdala and the ventral ACC (the two regions showing a higher order interaction with the reward – drive personality, see the PPI GLM results section) we used dynamic causal modelling (DCM) (Friston et al., 2003). DCM enables an alternative method of analysis of psychophysiological interactions within a hypothesis driven anatomical model. More speci fi cally, the DCM explains regional effects in terms of changing patterns of connectivity amongst regions according to experimentally induced contextual modulation of connection strengths. The principal advantage of DCM over the GLM implementa- tion of PPI analysis is the ability to make inferences about the directionality of causal connections. The DCM anatomical model was built from speci fi c hypotheses about the amygdala and the ventral ACC as key neural structures for the processing and recognition of emotional faces (Adolphs et al., 1999; Broks et al., 1998; Calder et al., 2001; Hornak et al., 2003). A 10 mm sphere ROI was created in the left amygdala by using the local maximum for each participant that was the nearest voxel to the activation peak in the left amygdala de fi ned by the whole group cluster (Supplementary Table 1). For the ventral ACC, a 15 mm sphere ROI was de fi ned using the local maxima for each subject that was the nearest voxel to the activation peak identi fi ed by the PPI analysis (see Results section, Analysis of effective connectivity 1: PPIs in the General Linear Model). The intrinsic connections (connectivity regardless the main effect of the task, DCM Bilinear matrix A value; see Fig. 2) were modelled as bidirectional in accord with anatomical evidence showing that the ventral ACC projects to the amygdala and vice versa (Aggleton et al., 1980; Amaral and Price, 1984; Ghashghaei et al., 2007; McDonald and Mascagni, 1996). The modulation by the emotion of faces was included as a bilinear effect expressing the contextual moderator (i.e. anger versus neutral context; DCM Bilinear matrix B value; see Fig. 2). A signi fi cant effect of the bilinear variable on connectivity indicates a PPI (Friston et al., 2003). We fi rst tested three different DCM models in which the driving inputs (i.e. presentation of faces regardless of the emotional expression) were ‘ injected ’ into different parts of the network (Supplementary Fig. 1). This ‘ injection ’ determines the origin of perturbation of the network, from which other points in the network will be activated according to the pattern of connectivity. For the fi rst “ parallel ” model (Fig. 2), face driving inputs (i.e., all faces, regardless of emotional expressions) were ‘ injected ’ into both amygdala and the ventral ACC. This was considered the more neurobiologically plausible model according to electrophysiological literature in animals (Leonard et al., 1985; Rolls, 2007) and humans (Eimer and Holmes, 2007; Eimer et al., 2003; Kawasaki et al., 2001; Oya et al., 2002) suggesting that the amygdala and ACC respond very quickly and within approximately the same time-scale window ( ∼ 110 – 220 ms) to faces. The two last “ serial ” models differ from the fi rst one with respect to where the driving inputs were injected: only in the amygdala (model 2) or only in the ventral ACC (model 3). When comparing all models using Bayesian model selection implemented within SPM5 software we assumed that all of them were equally likely a priori (Penny et al., 2004). We used the selection procedure which estimates the probability of each model given the data using Akaike's information criterion (AIC) and Bayesian's information criterion (BIC) approximations to each model's log-evidence or marginal likelihood (Penny et al., 2004). For every participant we found very strong evidence (see DCM results and Supplementary Fig. 2), in favour of the “ parallel ” model 1. Therefore using this model we further analyzed the impact of the driving input (all faces) (DCM matrix C value: effect of faces regardless of the expression) on both ROI activities, the intrinsic connectivity between the ROIs (DCM matrix A value: connectivity regardless the main effect of the task), and the modulatory effect by emotion (DCM matrix B value: angry vs. neutral context) on speci fi c bidirectional intrinsic connections (from amygdala to the ventral ACC and from the ventral ACC to amygdala) in each participant at a fi xed-effects level. One sample t tests were performed on the A-, B- and C-DCM matrix values to enable inference about the whole group (irrespective of any personality scores). Finally, individual B-, and C-DCM matrix values were entered into simple regression models with reward – drive, STAI (state or trait) anxiety, FNE (fear negative evaluation), and CES-D (depression) scores as main regressors in order to identify any speci fi c modulation by the reward-drive personality, anxiety or depression. The scores on the BAS/BIS subscales, on the Spielberger State and Trait anxiety (STAI), on the Fear of Negative Evaluation scale (FNE-Brief), and on the Center for Epidemiologic Studies Depression Scale (CES-D) were as follows: BAS reward-drive, range 6 to14 (0.5 – 80 percentile of the normal population), mean = 10.09, SD = 2.02; BAS- reward responsiveness, range 12 to 20 (0.4 – 87 percentile), mean = 16.66, SD = 1.85; BAS-fun seeking, range 7 to15 (0.8 – 87 percentile), mean = 11.66, SD = 2.29; BIS, range 17 to 28 (14 – 98 percentile), mean = 21.71, SD = 3.54; State anxiety, range 20 to 43 (1.7 – 94 percentile), mean = 30.71, SD = 6.76; Trait anxiety, range 21 to 52 (2.5 – 99 percentile), mean = 36.52, SD = 8.39; FNE range 0 to 42 (0 – 94 percentile), mean = 20.45, SD = 12.73; CES-D, range 1 to 24 (17 – 96 percentile), mean = 11, SD = 6.20. We found a borderline negative correlation between the reward – drive and BIS measures ( r = − .40, p = .06). Thus, to exclude any contribution from BIS scores, they were included as a covariate of no interest in the general linear model (GLM). Across the whole group, reaction times (RT) during the gender decision task were longer for angry (mean RT = 717 ms, SD = 88) than for neutral face trials (mean RT = 696 ms; SD = 74; t (20) = 2.46, p b .02). The difference in RT between angry and neutral face trials correlated negatively with reward – drive scores ( r = − .51, p b .02), re fl ecting faster gender categorization of angry faces with increasing reward – drive. This accords with previous research showing increased attention to angry faces in high reward – drive individuals (Putman et al., 2004). Again, to exclude any confounding effect of the response time, the differences in RT between angry and neutral faces trials were factored out in the PPI GLM model. There were no correlations between differences in RT and other BAS/BIS subscales, measures of anxiety, or depression scores ( r s b .23, p s N .15). In addition, task accuracy was consistently high across participants (mean accuracy = 94.5%, SD = 2.39) with no statistically signi fi cant correlations with any of the BAS/BIS subscales, measures of anxiety, or depression scores ( r s b .12, p s N .48). The PPI GLM showed a borderline negative connectivity between the left amygdala (source region) and the left ventral ACC across all participants (regardless any personality dimension) that did not meet the a priori threshold for signi fi cance ( x − 8, y 44, z 4; t = 2.89; p b .005, uncorrected) (one sample t test). However, our hypothesis was that the magnitude of this effect might re fl ect systematic individual differences in ...
Context 14
... the response time, the differences in RT between angry and neutral faces trials were factored out in the PPI GLM model. There were no correlations between differences in RT and other BAS/BIS subscales, measures of anxiety, or depression scores ( r s b .23, p s N .15). In addition, task accuracy was consistently high across participants (mean accuracy = 94.5%, SD = 2.39) with no statistically signi fi cant correlations with any of the BAS/BIS subscales, measures of anxiety, or depression scores ( r s b .12, p s N .48). The PPI GLM showed a borderline negative connectivity between the left amygdala (source region) and the left ventral ACC across all participants (regardless any personality dimension) that did not meet the a priori threshold for signi fi cance ( x − 8, y 44, z 4; t = 2.89; p b .005, uncorrected) (one sample t test). However, our hypothesis was that the magnitude of this effect might re fl ect systematic individual differences in reward – drive personality, representing a higher-order PPI. As predicted, the statistical parametrical map (SPM) of this higher-order PPI again identi fi ed the left ventral ACC and was highly signi fi cant ( x − 10, y 42, z − 10; t = 6.03; p b .005, Family Wise Error (FWE), small volume corrected (svc); Fig. 1 C). Moreover, it is striking that the left ventral ACC was one of only three regions that showed connectivity with the amygdala as a function of the anger context and the reward – drive personality ( x − 10, y 42, z − 10; t = 6.03; p b .001, uncorrected). The others regions were the dorsolateral prefrontal cortex ( x 26, y 34, z 34; t = 4.10; p b .001, uncorrected) that has been also implicated in aggression although to a lesser extent (Davidson et al., 2000), and the parietal cortex ( x 12, y − 52, z 74; t = 4.68; p b .001, uncorrected). Anger-related changes in the connectivity between the amygdala and the ventral ACC were highly correlated with the reward – drive scores ( r = .77, p b .001), ranging from more negative connectivity with lower reward – drive scores to less negative connectivity for higher reward – drive scores (Fig. 1 D, see also Supplementary Fig. 3). In the previous analysis, the time series for the source region was extracted from a participant-speci fi c local maximum in the left amygdala ROI, consistent with previous studies (Stephan et al., 2003). However, it is of note that we also obtained consistent results using a different approach in which the time series for each participant was extracted using the same center of the 10 mm sphere ROI for all participants (see PPI-GLM methods for details). Again, the left ventral ACC showed connectivity with the amygdala as a function of both the anger context and the reward – drive personality ( x − 12, y 40, z − 10; t = 4.80; p b .02, FWE svc). In both PPI analyses we did not fi nd any higher-order PPI between the amygdala – ventral ACC connectivity and other BAS/BIS measures (reward responsiveness, fun seeking or BIS) (no suprathreshold voxels even reducing the threshold at p b .005, uncorrected). We also tested for brain ‘ target ’ regions showing changes in connectivity with the amygdala as a function of the trait or state anxiety and we identi fi ed different areas, including the dorsal ACC ( x − 10, y 24, z 42; t = 4.27; p b .05, FWE, svc) and the ventrolateral prefrontal cortex (VLPFC) ( x − 32, y 24, z − 12; t = 4.11; p b .05, FWE, svc), which have been previously associated with individual differences in anxiety (Bishop et al., 2004; Bishop et al., 2007). The anger-related changes in the connectivity between the amygdala and the dorsal ACC and the VLPFC were positively correlated with state anxiety ( r = .69, p b .001 for the dorsal ACC; r = .65, p b .001 for the VLPFC), ranging from more negative connectivity with lower anxiety scores to less negative connectivity for higher anxiety scores. No signi fi cant higher-order PPI was found with the FNE (fear negative evaluation) scale (no suprathreshold voxels even reducing the threshold at p b .005, uncorrected). However, we identi fi ed the left ventral putamen as a region coupled with the left amygdala as a function of the CES-D (depression) score ( x − 12, y 8, z − 10; t = 5.21; p b .0001, uncorrected; r = .63, p b .005). In summary, the anger-related modulation of connectivity between the amygdala and the ventral ACC was strongly correlated with individual differences in reward – drive but not with other emotional dimensions (fun-seeking, reward-responsiveness, BIS, state and trait anxiety, FNE, and depression). Moreover, by covarying out any contribution by RT's and BIS scores, we have demonstrated that these variables do not account for the statistically signi fi cant effect of the reward – drive personality on amygdala-ventral ACC PPI. Using the Bayesian model selection procedure (Penny et al., 2004), we found strong evidence that the parallel model 1 was associated with the highest probability to explain the data (see Supplementary Fig. 2). Therefore we used model 1 to test for modulatory in fl uence of anger ( vs. neutral) expression on each speci fi c pathway (from ventral ACC to amygdala and from amygdala to ventral ACC). As predicted, face presentation (regardless of the emotional expression: DCM matrix C) had a very strong in fl uence on the neural activity of both amygdala and ventral ACC ROIs in all participants ( p s b .00001) (Fig. 3). Similarly, the intrinsic connectivity (DCM matrix A) between the ROIs in the whole sample was highly signi fi cant in both directions (from the ventral ACC to amygdala and vice versa ) ( p s b .00001) (Fig. 3). The main effect of the emotional expression (angry vs. neutral context: DCM Bilinear matrix B) enhanced the connectivity from ventral ACC to amygdala ( p b .002) but not vice versa ( p N .2) across individuals (one sample t test, irrespective of the reward – drive personality) (Fig. 3). The direct comparison between the DCM Bilinear matrix B's (B values from ventral ACC to amygdala vs. B values from amygdala to ventral ACC) con fi rmed that the anger-related changes in connectivity between the ventral ACC and amygdala were not symmetrical (paired t test, t (20) = 2.54, p b .02). Of particular interest, we found a signi fi cant higher-order interaction between the reward – drive scores and the subject-speci fi c effect of emotion on connectivity (DCM Bilinear matrix B: angry versus neutral context). There was a negative correlation between the reward – drive and the DCM bilinear moderator term (DCM Bilinear matrix B) for the connectivity in the speci fi c pathway from the ventral ACC to the amygdala ( r = − .50, p b .02) (Fig. 4). The reverse connection (from the amygdala to the ventral ACC) did not correlate with reward – drive ( r = .02, p N .90). Furthermore, there was no signi fi cant in fl uence of reward – drive on the driving inputs (presentation of faces regardless of the emotional expression: DCM Bilinear matrix C) to the amygdala or the ventral ACC (Fig. 4) and we found no correlations between STAI (state or trait anxiety), FNE (fear negative evaluation) or the CES-D (depression) scores and the B- or C-DCM Bilinear matrix values ( r s b .21, p s N .36). The speci fi city of reward – drive effect in the pathway from the ventral ACC to the amygdala was con fi rmed by comparing the r value derived from the correlation with reward – drive with the r values derived from the correlations with other personality dimensions ( t s N 2.7, p s b .05, Hottelling's t tests). This means that the anger-related effective connectivity from the ventral ACC to amygdala is the only critical pathway in fl uenced by the reward – drive personality but not by other emotional dimensions, such anxiety or depression. Group statistics for DCM results are summarized in Figs. 3 and 4 (one sample t tests and correlation with reward – drive scores). We have shown that individual differences in reward – drive (appetitive motivation) strongly modulate the neural connectivity between the ventral ACC and amygdala while viewing facial signals of aggression. This was addressed using two complementary methods — Psychophysiological Interactions (PPI) in a general linear model (GLM) and Dynamic Causal Modelling (DCM). PPI analyses have the advantage of being anatomically unconstrained, providing an objec- tive, data-driven approach. The PPI analysis in the whole sample (regardless of individual differences in reward – drive) identi fi ed the ventral ACC as showing a weak change in connectivity with the amygdala according to whether the faces displayed angry or neutral expressions (more negative connectivity for angry faces), although this effect did not meet our criteria for signi fi cance. However, when the individual differences in reward – drive were taken into consideration, we found that the change in connectivity between the same regions (ventral ACC and amygdala) was highly correlated with reward – drive, ranging from more negative to less negative values with increasing reward – drive. DCM analysis supported and extended these fi ndings by showing that this latter effect was restricted to connectivity from the ventral ACC to the amygdala, but not vice versa . Note also, that our results provide no evidence that connectivity between the amygdala and ventral ACC was modulated by the different measures of anxiety, other reward processing dimensions, or depression. Our previous research showed that regional activation within the amygdala and ventral ACC in response to viewing angry (relative to neutral or sad) expressions is correlated with individual differences in reward – drive (Beaver et al., 2008), a dimension consistently linked to the tendency to display hostile and aggressive behaviour (Carver, 2004; Cooper et al., 2008; Cornell et al., 1996; Diefendorff and Mehta, 2007; Putman et al., 2004; Smits and Kuppens, 2005). The present study goes signi fi cantly further by showing that it is speci fi cally ...
Context 15
... and depression (Ewbank et al., submitted; Leyman et al., 2007; Phan et al., 2006), we investigated any potential effect of the participants' STAI (state and trait anxiety) scores, FNE (fear negative evaluation) scores and CES-D (depression) scores on the connectivity between the amygdala and other potential brain ‘ target ’ regions (regression models). Two approaches to statistically threshold maps were applied. First, for small volume corrections (svc) within a priori regions of interest (ROI), the threshold was set at p b .05 Family Wise Error (Worsley et al., 1996). For the effect of reward – drive, we de fi ned a 15-mm sphere in the ventral ACC ROI using as center the local maxima derived from our previous study ( x − 15, y 36, z − 12) (Beaver et al., 2008). For the effect of anxiety the ROIs comprised the dorsal ACC (MNI local maxima: x − 2, y 12, z 40) and the ventrolateral prefrontal cortex (VLPFC) (MNI local maxima: x − 36, y 16, z − 6), de fi ned from previous work (Bishop et al., 2004; Bishop et al., 2007). Second, to explore other possible regions which were not predicted, a threshold of p b .001, uncorrected was used. To understand further the effective connectivity between the amygdala and the ventral ACC (the two regions showing a higher order interaction with the reward – drive personality, see the PPI GLM results section) we used dynamic causal modelling (DCM) (Friston et al., 2003). DCM enables an alternative method of analysis of psychophysiological interactions within a hypothesis driven anatomical model. More speci fi cally, the DCM explains regional effects in terms of changing patterns of connectivity amongst regions according to experimentally induced contextual modulation of connection strengths. The principal advantage of DCM over the GLM implementa- tion of PPI analysis is the ability to make inferences about the directionality of causal connections. The DCM anatomical model was built from speci fi c hypotheses about the amygdala and the ventral ACC as key neural structures for the processing and recognition of emotional faces (Adolphs et al., 1999; Broks et al., 1998; Calder et al., 2001; Hornak et al., 2003). A 10 mm sphere ROI was created in the left amygdala by using the local maximum for each participant that was the nearest voxel to the activation peak in the left amygdala de fi ned by the whole group cluster (Supplementary Table 1). For the ventral ACC, a 15 mm sphere ROI was de fi ned using the local maxima for each subject that was the nearest voxel to the activation peak identi fi ed by the PPI analysis (see Results section, Analysis of effective connectivity 1: PPIs in the General Linear Model). The intrinsic connections (connectivity regardless the main effect of the task, DCM Bilinear matrix A value; see Fig. 2) were modelled as bidirectional in accord with anatomical evidence showing that the ventral ACC projects to the amygdala and vice versa (Aggleton et al., 1980; Amaral and Price, 1984; Ghashghaei et al., 2007; McDonald and Mascagni, 1996). The modulation by the emotion of faces was included as a bilinear effect expressing the contextual moderator (i.e. anger versus neutral context; DCM Bilinear matrix B value; see Fig. 2). A signi fi cant effect of the bilinear variable on connectivity indicates a PPI (Friston et al., 2003). We fi rst tested three different DCM models in which the driving inputs (i.e. presentation of faces regardless of the emotional expression) were ‘ injected ’ into different parts of the network (Supplementary Fig. 1). This ‘ injection ’ determines the origin of perturbation of the network, from which other points in the network will be activated according to the pattern of connectivity. For the fi rst “ parallel ” model (Fig. 2), face driving inputs (i.e., all faces, regardless of emotional expressions) were ‘ injected ’ into both amygdala and the ventral ACC. This was considered the more neurobiologically plausible model according to electrophysiological literature in animals (Leonard et al., 1985; Rolls, 2007) and humans (Eimer and Holmes, 2007; Eimer et al., 2003; Kawasaki et al., 2001; Oya et al., 2002) suggesting that the amygdala and ACC respond very quickly and within approximately the same time-scale window ( ∼ 110 – 220 ms) to faces. The two last “ serial ” models differ from the fi rst one with respect to where the driving inputs were injected: only in the amygdala (model 2) or only in the ventral ACC (model 3). When comparing all models using Bayesian model selection implemented within SPM5 software we assumed that all of them were equally likely a priori (Penny et al., 2004). We used the selection procedure which estimates the probability of each model given the data using Akaike's information criterion (AIC) and Bayesian's information criterion (BIC) approximations to each model's log-evidence or marginal likelihood (Penny et al., 2004). For every participant we found very strong evidence (see DCM results and Supplementary Fig. 2), in favour of the “ parallel ” model 1. Therefore using this model we further analyzed the impact of the driving input (all faces) (DCM matrix C value: effect of faces regardless of the expression) on both ROI activities, the intrinsic connectivity between the ROIs (DCM matrix A value: connectivity regardless the main effect of the task), and the modulatory effect by emotion (DCM matrix B value: angry vs. neutral context) on speci fi c bidirectional intrinsic connections (from amygdala to the ventral ACC and from the ventral ACC to amygdala) in each participant at a fi xed-effects level. One sample t tests were performed on the A-, B- and C-DCM matrix values to enable inference about the whole group (irrespective of any personality scores). Finally, individual B-, and C-DCM matrix values were entered into simple regression models with reward – drive, STAI (state or trait) anxiety, FNE (fear negative evaluation), and CES-D (depression) scores as main regressors in order to identify any speci fi c modulation by the reward-drive personality, anxiety or depression. The scores on the BAS/BIS subscales, on the Spielberger State and Trait anxiety (STAI), on the Fear of Negative Evaluation scale (FNE-Brief), and on the Center for Epidemiologic Studies Depression Scale (CES-D) were as follows: BAS reward-drive, range 6 to14 (0.5 – 80 percentile of the normal population), mean = 10.09, SD = 2.02; BAS- reward responsiveness, range 12 to 20 (0.4 – 87 percentile), mean = 16.66, SD = 1.85; BAS-fun seeking, range 7 to15 (0.8 – 87 percentile), mean = 11.66, SD = 2.29; BIS, range 17 to 28 (14 – 98 percentile), mean = 21.71, SD = 3.54; State anxiety, range 20 to 43 (1.7 – 94 percentile), mean = 30.71, SD = 6.76; Trait anxiety, range 21 to 52 (2.5 – 99 percentile), mean = 36.52, SD = 8.39; FNE range 0 to 42 (0 – 94 percentile), mean = 20.45, SD = 12.73; CES-D, range 1 to 24 (17 – 96 percentile), mean = 11, SD = 6.20. We found a borderline negative correlation between the reward – drive and BIS measures ( r = − .40, p = .06). Thus, to exclude any contribution from BIS scores, they were included as a covariate of no interest in the general linear model (GLM). Across the whole group, reaction times (RT) during the gender decision task were longer for angry (mean RT = 717 ms, SD = 88) than for neutral face trials (mean RT = 696 ms; SD = 74; t (20) = 2.46, p b .02). The difference in RT between angry and neutral face trials correlated negatively with reward – drive scores ( r = − .51, p b .02), re fl ecting faster gender categorization of angry faces with increasing reward – drive. This accords with previous research showing increased attention to angry faces in high reward – drive individuals (Putman et al., 2004). Again, to exclude any confounding effect of the response time, the differences in RT between angry and neutral faces trials were factored out in the PPI GLM model. There were no correlations between differences in RT and other BAS/BIS subscales, measures of anxiety, or depression scores ( r s b .23, p s N .15). In addition, task accuracy was consistently high across participants (mean accuracy = 94.5%, SD = 2.39) with no statistically signi fi cant correlations with any of the BAS/BIS subscales, measures of anxiety, or depression scores ( r s b .12, p s N .48). The PPI GLM showed a borderline negative connectivity between the left amygdala (source region) and the left ventral ACC across all participants (regardless any personality dimension) that did not meet the a priori threshold for signi fi cance ( x − 8, y 44, z 4; t = 2.89; p b .005, uncorrected) (one sample t test). However, our hypothesis was that the magnitude of this effect might re fl ect systematic individual differences in reward – drive personality, representing a higher-order PPI. As predicted, the statistical parametrical map (SPM) of this higher-order PPI again identi fi ed the left ventral ACC and was highly signi fi cant ( x − 10, y 42, z − 10; t = 6.03; p b .005, Family Wise Error (FWE), small volume corrected (svc); Fig. 1 C). Moreover, it is striking that the left ventral ACC was one of only three regions that showed connectivity with the amygdala as a function of the anger context and the reward – drive personality ( x − 10, y 42, z − 10; t = 6.03; p b .001, uncorrected). The others regions were the dorsolateral prefrontal cortex ( x 26, y 34, z 34; t = 4.10; p b .001, uncorrected) that has been also implicated in aggression although to a lesser extent (Davidson et al., 2000), and the parietal cortex ( x 12, y − 52, z 74; t = 4.68; p b .001, uncorrected). Anger-related changes in the connectivity between the amygdala and the ventral ACC were highly correlated with the reward – drive scores ( r = .77, p b .001), ranging from more negative connectivity with lower reward – drive scores to less negative connectivity for higher reward – drive scores (Fig. 1 D, see also Supplementary Fig. 3). In the previous analysis, the time series for ...

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... To achieve the goal mentioned above, we further conducted a dynamic causal modelling analysis to test directional information flow between the brain regions involved in phantom inferior and phantom superior conditions (Friston et al. 2003). DCM estimates three sets of parameters, including the intrinsic connections between regions independent of experimental context, the driving effect of external stimuli on specific regions, and the modulatory effect of stimuli on the effective connectivity between regions (Ewbank et al. 2011;Passamonti et al. 2008). Consistent with common approaches (Gandolla et al. 2014;Passamonti et al. 2008;Rothkirch et al. 2018), the nodes in our models were identified based on brain regions identified in our previous network connectivity analysis. ...
... DCM estimates three sets of parameters, including the intrinsic connections between regions independent of experimental context, the driving effect of external stimuli on specific regions, and the modulatory effect of stimuli on the effective connectivity between regions (Ewbank et al. 2011;Passamonti et al. 2008). Consistent with common approaches (Gandolla et al. 2014;Passamonti et al. 2008;Rothkirch et al. 2018), the nodes in our models were identified based on brain regions identified in our previous network connectivity analysis. In the phantom inferior condition, we create a 6-mm sphere ROI in the left caudate and the left vACC (see Tables 1 and 2). ...
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