Abstract

Introduction

Aging is associated with well-known co-morbidities and losses, but also with relatively high levels of emotional well-being. The idea of relatively well-preserved emotional processing in aging is supported by evidence showing that older adults tend to (a) pay attention to and remember more positive information (Charles et al., 2003; Mather and Carstensen, 2003; Isaacowitz et al., 2006) and (b) show reduced processing of negative information compared to young adults (Wood and Kisley, 2006; Gruhn et al., 2007).

Prominent models of emotion identify valence and arousal as fundamental components of emotion (see Bradley and Lang, 2000, for a review). Valence refers to the direction of an emotional response (positive or negative), whereas arousal refers to the magnitude of the response (exciting, agitating, or calming, subduing; Russell, 1980). Empirical evidence shows that these two emotional dimensions are not independent of each other (Ito et al., 1998; Lang et al., 1998; Libkuman et al., 2007; but see Ribeiro et al., 2007). Rather, they form a V (“boomerang”)-shaped function, with the unpleasant pictures tending to be more highly arousing than pleasant stimuli, and both pleasant and unpleasant pictures being more arousing than neutral stimuli. Considerable evidence supports the “boomerang” shape in averaged data on arousal and valence ratings of people's reactions to affective visual stimuli, such as the International Affective Picture System (IAPS) (e.g., Lang et al., 1992, 1998; Lang, 1995; Bradley and Lang, 2007). Despite substantial support for the preserved emotional function in aging, the role of emotional arousal has not been systematically investigated in neuroimaging studies. Moreover, the few behavioral studies that included examinations of arousal have produced inconsistent findings. For instance, a study investigating age-differences in memory for arousing and non-arousing words (Kensinger, 2008) showed that older adults remembered more positive than negative low-arousing words, whereas young adults showed the reverse pattern. There were no differences in the ratio of high-arousing positive vs. negative words remembered by young and older adults. A study examining age-differences in the relation between valence and arousal ratings (Keil and Freund, 2009) showed that in young adults both pleasantness and unpleasantness increased with emotional arousal, whereas in older adults low-arousing stimuli were experienced as most pleasant, and the high-arousing ones as most unpleasant. Finally, a study investigating age-differences in emotional reactions to stimuli differing in arousal and age-relevance (Streubel and Kunzmann, 2011) showed that older adults rated unpleasant low-arousing pictures as less unpleasant compared to young adults, while there were no age-related differences in unpleasant ratings for unpleasant pictures that were high in arousal. Despite these inconsistent findings, these behavioral studies indicate that age-related changes are more likely to influence the response to stimuli low in arousal. This idea is also suggested by recent neuroimaging evidence (St. Jacques et al., 2010) showing that older adults tend to rate some negative pictures as neutral more frequently than young adults (thus suggesting a negative-to-neutral shift in older adults). However, the latter study did not explicitly manipulate the level of arousal.

Previous evidence has shown that processing of low and high arousing emotional stimuli relies on distinct processes. On the one hand, low arousing negative stimuli activate more goal-driven processes, which tend to engage controlled, resource-demanding processes (Kensinger and Corkin, 2004) and the prefrontal cortex (PFC). On the other hand, high arousing information activates more stimulus-driven processes (Mather and Knight, 2006), which tend to capture attention automatically and require reduced cognitive effort (Dolan, 2002). There is evidence for the idea that the automatic processing of high-arousing stimuli is relatively preserved in older adults (Mather and Knight, 2006). One structure typically associated with the relatively automatic processing of emotional information is the amygdala. Amygdala, a region involved in basic emotion processing, is involved in two related and important abilities: (a) to rapidly detect emotional information presented with a rapid stream of stimuli (Anderson and Phelps, 1998) and (b) to detect emotional stimuli even when attentional resources are drained (reviewed by Dolan and Vuilleumier, 2003). These observations suggest that the role of the amygdala in emotional processing is not heavily dependent on the availability of extensive cognitive resources. Despite a relative structural preservation of the amygdala in healthy aging (Allen et al., 2005; Brabec et al., 2010), functional magnetic resonance imaging (fMRI) evidence reveals different patterns of activation in the amygdala. For instance, some fMRI studies have found an age-related decrease in activation in response to negative stimuli (Iidaka et al., 2002; Gunning-Dixon et al., 2003; Mather et al., 2004; Tessitore et al., 2005; Erk et al., 2008). One study reported robust amygdala activity in both young and older adults during the perception of novel fearful faces (vs. familiar neutral ones) (Wright et al., 2006), while another study found enhanced amygdala activity to negative compared to neutral stimuli in both young and older adults (St. Jacques et al., 2010). Importantly, the latter study also showed that the amygdala activation in older adults involved overlapping areas with young adults, thus suggesting that amygdala functions similarly in healthy young and older adults. This makes it unlikely that an age-related decline in the amygdala (as suggested by the aging-brain model: Cacioppo et al., 2011) would account for the reduced amygdala activity to negative stimuli in older adults reported in some of the previous studies.

A more probable explanation for the inconsistent findings regarding age-related differences in amygdala activation to negative stimuli may be that the pictures used in those studies differed in emotional arousal. This explanation is in line with previous evidence in older adults showing (a) preserved amygdala responses to positive (Mather et al., 2004) or novel stimuli (Moriguchi et al., 2011), (b) reduced responses selectively to negative stimuli, and (c) decreased amygdala activity for the trials in which older participants subjectively experienced negative pictures as neutral (negative-to-neutral shift), but not for the negative pictures subjectively rated as negative (St. Jacques et al., 2010). Taken together, these findings suggest the possibility of age-related differential engagement of the amygdala by stimuli with different levels of arousal, but again such manipulation has not been previously used in conjunction with brain imaging recordings.

Decreased amygdala activity, combined with increased activity in emotion control regions, such as the medial PFC and the adjacent anterior cingulate cortex (ACC), might also be the result of a greater focus on emotion regulation goals. According to the Socioemotional Selectivity Theory (SST; Scheibe and Carstensen, 2010), older adults tend to prioritize social and emotional well-being goals over other goals, potentially as a result of shrinking time horizons. The increased salience of emotional goals may enhance older adults' motivation to regulate the emotions experienced in everyday life, either by selecting stimuli and situations that minimize negative emotions (Blanchard-Fields et al., 2004) or by using emotion regulation strategies (Gross et al., 1997). The “cognitive-control model” extension of the SST (Mather and Knight, 2005; Kryla-Lighthall and Mather, 2009) posits that such negativity avoidance is the result of older adults' greater chronic focus on emotion regulation goals. Consistent with the cognitive control model, a number of studies reported increased activity in the medial PFC/ACC to negative compared to neutral stimuli in older compared to young adults (Gunning-Dixon et al., 2003; Williams et al., 2006; Leclerc and Kensinger, 2008; Roalf et al., 2011). Moreover, studies also showed that the increased activity in medial PFC/ACC was accompanied by decreased activity in the amygdala in older, but not in young adults, during the anticipation of monetary loss (Larkin et al., 2007) and during evaluation of negative stimuli (St. Jacques et al., 2010). Notably, functional connectivity between these regions was greater in older compared to young adults, thus suggesting that medial PFC and ACC might be involved more generally in subcortical emotion regulation.

This interpretation is consistent with studies showing interactions between similar medial PFC/ACC regions and the amygdala, when older adults voluntarily decreased emotional responses to negative stimuli (Urry et al., 2006; Winecoff et al., 2011). Given that medial PFC shows stronger activity when adults (a) are told to up-regulate positive emotion and down-regulate negative emotion (Ochsner et al., 2004) and (b) spontaneously regulate their emotions (e.g., Drabant et al., 2009), the increased medial PFC/ACC activity seen in older adults while processing emotional stimuli might reflect their spontaneous engagement of emotion regulation operations. Moreover, negative correlations between the ventral ACC and amygdala when evaluating negative pictures (according to IAPS standardized norms) as neutral (negative-to-neutral shift; St. Jacques et al., 2010) suggest that the spontaneous emotion regulation in older adults might be limited to low arousing stimuli.

The present event-related fMRI study used a broader range of negative emotional stimuli (low, medium, and high arousing) to test the hypothesis that emotional functioning in aging is modulated by the level of arousal, and to identify the associated neural correlates. The focus was on the ACC/vmPFC and the amygdala. Participants were presented with negative and neutral pictures, which they rated for emotional content, while fMRI data were recorded. Based on the above review, we made the following four predictions. First, from the evidence showing a negative-to-neutral shift in older adults' ratings, we predicted lower ratings to the low arousing negative pictures in older adults. Second, we predicted that common engagement of the amygdala in young and older adults would be specific to high arousing pictures, reflecting preserved responses to high arousing stimuli in older adults. Third, we predicted that opposing patterns of response in the ACC/vmPFC (increased) vs. amygdala (decreased) would be specific to low arousing stimuli. Finally, consistent with a role of the vACC/vmPFC in spontaneous emotional regulation, we explored the possibility that increased activity in this region would be linked to reduced ratings for low arousing negative stimuli in older adults.

Methods

Results

fMRI results

Common engagement of the amygdala in young and older groups driven by high arousing stimuli

Conjunction analyses of brain activity associated with the evaluation of negative and neutral pictures identified an area in the right amygdala that was commonly engaged by both age groups (see Table ​Table3;3; Figure ​Figure1).1). Consistent with previous evidence showing common engagement of the amygdala to negative compared to neutral stimuli by both age-groups (St. Jacques et al., 2010), we did not find significant differences in this region in an ANOVA examining Valence (Negative and Neutral) × Age Group (Young and Older) interaction. Analyses looking at the effect of arousal revealed that the common engagement of the right amygdala in the two age-groups was driven by the high arousing negative stimuli, which also activated left amygdala in both groups. Further analyses identified amygdala activation to low, medium, and high arousing negative stimuli in younger adults, but only to high and medium arousing negative stimuli in older adults. However, there were no overlapping areas in the brain regions engaged by the low and medium arousing pictures. The Arousal (NegLo vs. NeuAll, NegMed vs. NeuAll, and NegHi vs. NeuAll) × Age Group (Young and Older) interaction was not significant in the amygdala region commonly engaged by young and older adults in response to negative compared to neutral pictures, but it was significant (F = 4.55, p < 0.05) for the peak voxel showing decreased amygdala activity to low-arousing stimuli in the older compared to young adults (discussed below). Although the interaction was not significant in the amygdala region commonly engaged by young and older adults in response to negative compared to neutral pictures, our findings are still consistent with the idea that the overlap is more likely to occur in high-arousing stimuli, and with our prediction that amygdala activity will be associated with minimal age-related differences for high arousing negative stimuli, but will show age-related differences for the low-arousing negative stimuli. This differential impact is also reflected in the results of the follow-up pairwise comparisons showing age-related differences in the amygdala to low, but not to medium and high arousing negative pictures. T-tests comparing amygdala activation to high arousing negative stimuli revealed reduced activity to the high arousing negative pictures in temporal, occipital, parietal, and cingulate areas, and to the medium arousing pictures in occipital areas (see Table ​Table4)4) in older compared to the young adults. In addition to the right amygdala, high arousing stimuli also engaged a common area in the extra striate cortex (Talairach coordinates: x = 48, y = −74, z = 7), in both young and older adults. As described below, low arousing pictures were associated with different patterns of activity in young and older adults.

Table 3

Common amygdala activity for negative vs. neutral stimuli.

Brain region	H	Voxels	Talairach coordinates			t
			x	y	z
YOUNG ∩ OLDER (NegAll vs. NeuAll)
Amygdala	R	6	28	−1	−20	3.86
YOUNG ∩ OLDER (NegHi vs. NeuAll)
Amygdala	L	6	−20	−5	−17	3.98
Amygdala	R	22	16	−5	−17	3.11*
			28	−1	−20	2.86*

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H, Hemisphere. t-values represent the multiplied score from the conjunction analysis of young and older groups. Bolded t-values indicate the voxels surviving a voxel-level threshold of p < 0.05 (FDR-corrected).

^*Denotes significant difference at a cluster-level threshold of p < 0.05 (FDR-corrected).

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Figure 1

Common amygdala activation for high arousing stimuli in young and older adults. Common engagement of the right amygdala by young and older groups was identified using conjunction analysis based on a region of interest approach, where both young and older groups showed common activity for negative vs. neutral (blue area) and high arousing negative vs. neutral (red area) stimuli (p = 0.0025). The bar graph illustrates the parameter estimates corresponding to the peak voxel in the area of R AMY commonly activated by young and older adults for NegAll vs. NeuAll contrast. L, left; R, right; NegHi, Negative High Arousal; NegMed, Negative Medium Arousal; NegLo, Negative Low Arousal; NegAll, Negative All; NeuAll, Neutral All.

Table 4

Dissociable brain activity for negative vs. neutral stimuli by arousal levels in young and older adults.

Contrast	Brain region	BA	H	Voxels	Talairach coordinates			t
					x	y	z
YOUNG > OLDER
High arousal (NegHi vs. NeuAll)
Cuneus		18	R	26	12	−85	19	4.26
					8	−92	19	3.71
Precuneus		19	R	12	28	−60	36	3.94
Middle temporal gyrus		19	R	21	48	−61	14	3.85
Cingulate gyrus		32	L	17	−4	17	32	3.69
Postcentral gyrus		2	R	10	51	−21	42	3.66
Middle temporal gyrus		19	L	18	−44	−61	14	3.60
Middle temporal gyrus		37			−51	−62	3	2.83
Medium arousal (NegMed vs. NeuAll)
Middle occipital gyrus		18	L	21	−32	−89	4	3.47
					−24	−89	15	3.38
Low arousal (NegLo vs. NeuAll)
Amygdala		34	L	11	−20	−1	−10	2.49*
					−32	−5	−17	2.10*
Amygdala		28	R	18	16	−4	−10	2.44*
		34			28	3	−14	1.96*
Inferior frontal gyrus		47	R	34	44	11	−4	4.81
Superior temporal gyrus		41	R	13	40	−35	9	4.02
					48	−31	5	3.17
					40	−38	16	2.82
Middle temporal gyrus		39	R	23	48	−61	21	3.85
					44	−54	14	3.31
					48	−62	10	2.99
Superior frontal gyrus		9	R	26	40	40	31	3.79
					16	52	38	3.78
					4	56	38	3.67
Superior frontal gyrus		9	L	22	−28	52	34	3.77
					−12	52	38	3.62
Middle occipital gyrus		19	L	14	−28	−77	11	3.75
					−32	−85	8	3.43
					−24	−89	15	3.09
Inferior frontal gyrus		47	L	20	−48	42	−9	3.75
					−51	30	−5	2.94
					−55	35	2	2.86
Middle frontal gyrus		8	R	32	36	22	47	3.68
					48	21	39	3.67
					32	6	58	3.25
Superior temporal gyrus		38	L	40	−44	11	−14	3.64
					−40	23	−11	3.47
					−51	7	−7	3.32
OLDER > YOUNG
Low arousal (NegLo vs. NeuAll)
Anterior cingulate gyrus		32	L	39	−16	36	13	4.22
					−12	43	−2	2.42
		32	R	8	8	40	16	1.88

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BA, Brodmann's area; H, Hemisphere. A threshold of p < 0.005 (uncorrected) was used. Bolded t-values indicate the voxels surviving a cluster-level threshold of p < 0.05 (FDR-corrected).

^*Denotes significant difference at p < 0.05 (uncorrected).

Opposing spontaneous responses in rostral/ventral ACC and amygdala activity in older adults driven by low-arousing pictures

Confirming our third prediction, targeted two-sample t-tests revealed an age-related increase to low arousing stimuli in the rostral/ventral ACC (Tables ​(Tables4,4, ​,5).5). In older adults this region showed activation, whereas in young adults it showed deactivation. Deactivation in this area is not surprising, as a variety of previous fMRI studies have shown that deactivation in medial frontal areas is rather common during tasks that entail goal-directed behavior (Frankenstein et al., 2003). Deactivations in this region typically occur when resources are allocated to other brain regions, possibly to facilitate task-relevant processing (Frankenstein et al., 2003). Importantly, this region partially overlapped with the ACC region showing a significant Arousal × Age Group interaction (F = 12.70, p < 0.005). Targeted two-sample t-tests also revealed an age-related decrease in the bilateral amygdala activity, for the low arousing pictures (see Figure ​Figure2).2). Moreover, the peak voxel showing decreased amygdala activity to low arousing stimuli in older compared to the young adults also survived the Arousal × Age Group interaction (F = 4.55, p < 0.05). As illustrated in Figure ​Figure2,2, rostral/ventral ACC activation was significant only for the older group, whereas the amygdala activation was significant only for the young group. In addition, young adults showed increased activity in frontal, temporal, and occipital areas (see Table ​Table44).

Table 5

Mean parameter estimates for peak voxel activity in anterior cingulate cortex (ACC) and amygdala (AMY) for young and older groups.

Brain region		Age group
		Young (n = 18)	Older (n = 16)
ACC	NegHi	1.35 (1.42)	−4.93 (2.27)
	NegMed	−4.91 (2.08)	−3.08 (1.98)
	NegLo	−4.29 (1.48)	2.39 (1.35)
	NeuAll	−1.78 (1.83)	−4.68 (1.60)
AMY	NegHi	22.93 (7.18)	12.88 (4.92)
	NegMed	15.18 (5.07)	2.34 (4.34)
	NegLo	15.83 (4.44)	−0.93 (3.96)
	NeuAll	6.74 (2.29)	4.12 (3.20)

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Values before parentheses indicate the means. Values in parentheses indicate the standard errors of the means. The mean parameter estimates were extracted in each of the four conditions against the baseline activity for each age group at the coordinates corresponding to the peak voxels for each of the ACC and AMY regions showing overlapping activity between (1) the Arousal × Age Group interaction and (2) the two-sample t-test targeting low arousing stimuli.

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Figure 2

Opposing patterns of response in rostral/ventral ACC and AMY for low arousing stimuli. Increased activity in rostral/ventral ACC (top sagittal image), and decreased activity in the amygdala (bottom coronal image) in older compared to young adults was identified using two-sample t-tests between activation maps for NegLo vs. NeuAll contrast in the two groups. The bar graphs on the right illustrate the parameter estimates corresponding to the peak voxels in the area of ACC and AMY showing increased activity to low arousing negative stimuli in the young and older groups. L, left; R, right; NegHi, Negative Hi Arousal; NegMed, Negative Medium Arousal; NegLo, Negative Low Arousal; NeuAll, Neutral All.

Age-related increased activity in ventral ACC/ventromedial PFC was linked to lower ratings for low arousing negative stimuli

Co-variations of activity in the vACC/vmPFC with the behavioral ratings further elucidated the role played by this region in the evaluation of low arousing stimuli in older adults (see Figure ​Figure3).3). As illustrated in the figure, the vACC/vmPFC (Talairach coordinates: x = 0, y = 38, z = −9) activity was negatively correlated with the ratings for low arousing negative pictures in the older adults (r = −0.72, p < 0.005). That is, older participants who engaged this region when processing low arousing negative pictures also rated those pictures as less negative. Of note, portions of the vACC/vmPFC showing the negative co-variation with ratings for low arousing pictures in older adults partially overlapped with the vACC/vmPFC area showing stronger response to low arousing negative stimuli in older, compared to the young adults. The correlation between vACC/vmPFC and ratings was specific to ratings for low arousing negative pictures in older adults, as indicated by the significant difference between this correlation and the similar correlation for the young group (using the r to z transformation, z = −4.06, p < 0.0001). There were no other significant correlations between the vACC/vmPFC and ratings. The significant co-variations between other brain areas and behavioral ratings are presented in Table ​Table66.

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Figure 3

Activity in the ACC was linked to reduced ratings for low-arousing stimuli in older adults. In older adults, increased activity in the ventral anterior cingulate cortex (vACC)/ventro-medial prefrontal cortex (vmPFC) correlated negatively with the ratings for low arousing negative stimuli. The scatterplot is based on the parameter estimates corresponding to the peak voxel in the area of vACC/vmPFC showing negative correlation with the behavioral ratings. NegLo, Negative Low Arousal; NeuAll, Neutral All.

Table 6

Co-variations between brain activity and the ratings of negative pictures by young and older adults.

(Contrast) × Ratings	r value	Brain region	BA	H	Voxels	Talairach coordinates			t
						x	y	z
YOUNG
(NegHi vs. NeuAll) × NegHi	−0.668	Inferior frontal gyrus	47	L	10	−20	31	−5	3.59
(NegLo vs. NeuAll) × NegLo	−0.726	Parahippocampal gyrus	35	L	14	−20	−35	−5	4.22
OLDER
(NegHi vs. NeuAll) × NegHi	+0.803	Precuneus	7	L	56	−4	−53	43	5.04
	+0.770					0	−45	28	4.52
	+0.705		7	R		12	−52	43	3.72
	+0.778	Precentral gyrus	9	L	12	−36	21	39	4.64
	+0.769	Superior parietal lobule	7	R	16	28	−68	44	4.50
	+0.746	Precuneus	7	L	10	−12	−59	55	4.19
	+0.722					−12	−68	51	3.90
	+0.707	Medial frontal gyrus	8		12	0	45	38	3.74
	+0.707					0	56	30	3.74
	+0.669	Medial frontal gyrus	9	L		−4	40	31	3.37
	+0.690	Superior frontal gyrus	9	L	14	−8	60	26	3.57
	+0.679			R		8	63	15	3.45
(NegMed vs. NeuAll) × NegMed	−0.819	Inferior parietal lobule	40	L	11	−40	−29	42	5.34
	−0.686					−28	−37	42	3.52
	−0.797	Precentral gyrus	6	R	10	32	−9	56	4.94
	−0.783	Precentral gyrus	6	L	26	−24	−10	52	4.70
	−0.699					−16	−1	55	3.65
	−0.699					−24	−1	48	3.65
	−0.777	Precentral gyrus	6	L	13	−55	−2	41	4.62
	−0.774	Precuneus	7	R	26	8	−59	62	4.58
	−0.668					4	−56	51	3.35
	−0.751	Precuneus	7	L	11	−28	−71	55	4.25
	−0.749	Caudate nucleus		R	20	4	8	0	4.23
	−0.711			L		−4	4	−4	3.79
	−0.739	Lentiform nucleus		R	19	20	−4	8	4.11
	−0.712	Inferior parietal lobule	40	L	21	−44	−36	57	3.79
	−0.700					−40	−47	61	2.67
	−0.710	Superior temporal gyrus	22	R	10	60	−7	8	3.77
	−0.708					51	4	7	3.75
	−0.675					48	5	15	3.43
(NegLo vs. NeuAll) × NegLo	+0.750	Insula	13	R	12	28	−26	23	4.24
	+0.743					36	−45	28	4.22
	+0.767					32	−34	24	4.04
	+0.711	Supramarginal gyrus	40	L	11	−44	−45	32	4.16
	+0.653	Superior frontal gyrus	8	R	10	4	37	46	3.53
(NegLo vs. NeuAll) × NegLo	−0.577	Anterior cingulate	32	R	7	0	38	−9	4.11

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BA, Brodmann's area; H, Hemisphere. A threshold of p < 0.005 (uncorrected) was used.

Discussion

Despite substantial evidence supporting the idea of enhanced affective well-being and emotional stability in healthy aging, relatively little is known about the role of emotional arousal in this effect and the underlying brain mechanisms. The current study addressees this gap in the emotional aging literature by investigating the effect of emotional arousal on behavioral and neural responses in young and older adults. There were three main novel findings regarding the neural correlates. First, we showed that the common engagement of the right amygdala in young and older adults was driven by high arousing stimuli. Second, we showed that the opposing spontaneous pattern of increased activity in the rostral/ventral ACC and decreased activity in the right amygdala is specific to low arousing stimuli. Third, we linked the increased spontaneous activity in the vACC/vmPFC to older adults' reduced ratings for low arousing stimuli. These findings are discussed below.

Conclusion

In the present study, we examined the effect of arousal as a potential factor influencing the enhanced affective well-being and emotional stability commonly associated with healthy aging. There were three novel findings regarding the neural correlates of emotion processing: (a) right amygdala was commonly engaged by young and older adults only during the evaluation of high arousing stimuli, (b) amygdala and rostral/ventral ACC showed an opposing pattern of activity for low arousing stimuli in older compared to young adults, and (c) the engagement of the ventral ACC/vmPFC in older adults reflected successful regulation of low arousing negative stimuli. These findings highlight the important effect of arousal on age-related emotional processing, suggesting that aging is associated with preserved emotional processing of high arousing negative information, and with altered processing of low arousing negative information. By showing that older adults engage more automatic processes when evaluating high arousing negative information, and more controlled, resource-demanding processes in response to low arousing negative information, the present study advances our understanding of the neural correlates underlying the enhanced emotional well-being in healthy aging. Moreover, by linking the spontaneous engagement of the emotion control regions in older adults to reduced subjective experiencing of low arousing negative information, the present study provides further evidence supporting the idea that emotion regulation is chronically activated in healthy aging, and clarifies that this effect is specific to low arousing negative information. This new evidence highlights the need of adopting a comprehensive approach that takes into consideration both the valence and arousal in examining emotional aging.

Acknowledgments

References