Electrophysiological evidence for adult age-related sparing and decrements in emotion perception and attention

ERP evidence of age-related differences in emotional processing

The present study used event-related potentials (ERPs) to examine differences in the temporal dynamics of emotion processing in young and older adults, with a specific focus on the positivity effect, that is, the preferential processing of positive over negative information. To this aim, we used a language paradigm that allowed us to investigate early ERP components as well as later components, namely the N400 and the late positive complex (LPC). Young and older adults were presented with neutral sentence stems with positive, negative or neutral/semantically-incongruent critical word endings while their electrical brain activity was recorded. There were no effects of emotional valence on early ERP components. Instead, a positivity effect was evident in young adults indexed by reduced N400s for positive sentence endings. Perhaps due to reduced semantic processing abilities, older adults did not show any N400 effect. ERP effects in this group were evident at a later processing stage and took the form of larger LPCs for neutral/incongruent information. Overall, there was no effect of emotional valence on either the N400 or the LPC in older adults. Our data suggest that with age, more effortful semantic processing may deplete resources for emotional processing.

Global-local processing and dispositional bias interact with emotion processing in the psychological refractory period paradigm

The reciprocal link between scope of attention and emotional processing is an important aspect of the relationship between emotion and attention. Larger scope of attention or global processing has been linked to positive emotions and narrow scope of attention or local processing has been linked to negative emotions. The nature of this relationship in the context of central capacity limitations and individual differences in attentional processing has not been studied in detail so far. To investigate such a relationship, here we used the psychological refractory period (PRP) paradigm, in which we manipulated the stimulus onset asynchrony (SOA: 150 ms, 300 ms, 900 ms) of stimuli corresponding to two tasks in a sequence. The first task was identifying a number at the global or local level; the second task was recognizing the emotional expression (happy or angry). Additionally, predisposition towards local or global perceptual dimension was measured with the global-local task. Results indicated that global precedence modulated PRP effect and that response accuracy was impaired by the combination of local-angry task modalities. Interestingly, interference between simultaneous tasks was modulated by the predisposition to different perceptual levels resulting in different cognitive strategies for performing simultaneous tasks: locally biased subjects tended more towards serial processing, meanwhile globally biased ones were performing tasks in a parallel manner. This result suggest that individual differences may play a role in the choice of dual-task performing strategies.

An Electrophysiological Study of Cognitive and Emotion Processing in Type I Chiari Malformation

Type I Chiari malformation (CMI) is a neurological condition in which the cerebellar tonsils descend into the cervical spinal subarachnoid space resulting in cervico-medullary compression. Early case-control investigations have indicated cognitive deficits in the areas of attention, memory, processing speed, and visuospatial function. The present study further examined cognitive and emotional processing deficits associated with CMI using a dual-task paradigm. Nineteen CMI patients were recruited during pre-surgical consultation and 19 matched control participants identified emotional expressions in separate single and asynchronous dual-task designs. To extend earlier behavioral studies of cognitive effects in CMI, we recorded event-related potentials (ERPs) in the dual-task design. Though response times were slower for CMI patients across the two tasks, behavioral and ERP analyses indicated that patients did not differ from matched controls in the ability to allocate attentional resources between the two tasks. P1 ERP component analyses provided no indication of an emotional arousal deficit in our CMI sample while P3 ERP component analyses suggested a CMI-related deficit in emotional regulation. P3 analysis also yielded evidence for a frontalization of neurophysiological activity in CMI patients. Pain and related depression and anxiety factors accounted for CMI deficits in single-task, but not dual-task, response times. Results are consistent with a dysfunctional fronto-parietal attentional network resulting from either the indirect effects of chronic pain or the direct effects of CMI pathophysiology stemming from cervico-medullary compression.

Emotional arousal deficit or emotional regulation bias? An electrophysiological study of age-related differences in emotion perception

Background/Study context: Adult age differences in emotion processing have been attributed to age-related decline in earlier emotional perception and age-related bias in later emotional regulation. Yet, the relationship between the processes of early emotion perception and bias in emotional regulation and their influence on behavioral outcomes remains unclear. Event-related potentials (ERPs) have the temporal precision to allow for the online measure of neurophysiological activity and provide potential insight into the complex dynamics of emotion processing and aging.

METHODS

ERPs were used as the primary measure to examine the hypotheses that younger adults will differ in emotional arousal and emotional bias as represented by the early P1 waveform and later P3 waveform, respectively. Thirty-two younger and older adults (16 each) performed a facial emotion discrimination task in which they identified standardized angry, happy, or neutral expressions of faces from the NimStim database.

RESULTS

Younger adults showed a greater P1 ERP for angry faces relative to happy faces at parietal channels, while older adults did not exhibit any emotional modulation of the P1. In contrast, both younger and older adults showed a greater late P3 ERP for angry faces compared to happy faces.

CONCLUSION

The authors' results provide evidence for an age-related deficit in early emotion perception and autonomic arousal. Younger adults, but not older adults, exhibited a pattern of neurophysiological activity believed to reflect preconscious and reflexive identification of threat. Despite these age group differences in early emotion processing, younger and older adults did not exhibit differences in neurophysiological processes believed to reflect emotion regulation.

Regional gray matter correlates of memory for emotion-laden words in middle-aged and older adults: A voxel-based morphometry study

Emotional content is known to enhance memory in a content-dependent manner in healthy populations. In middle-aged and older adults, a reduced preference for negative material, or even an enhanced preference for positive material has been observed. This preference seems to be modulated by the emotional arousal that the material evokes. The neuroanatomical basis for emotional memory processes is, however, not well understood in middle-aged and older healthy people. Previous research on local gray matter correlates of emotional memory in older populations has mainly been conducted with patients suffering from various neurodegenerative diseases. To our knowledge, this is the first study to examine regional gray matter correlates of immediate free recall and recognition memory of intentionally encoded positive, negative, and emotionally neutral words using voxel-based morphometry (VBM) in a sample of 50-to-79-year-old cognitively intact normal adults. The behavioral analyses yielded a positivity bias in recognition memory, but not in immediate free recall. No associations with memory performance emerged from the region-of-interest (ROI) analyses using amygdalar and hippocampal volumes. Controlling for total intracranial volume, age, and gender, the whole-brain VBM analyses showed statistically significant associations between immediate free recall of negative words and volumes in various frontal regions, between immediate free recall of positive words and cerebellar volume, and between recognition memory of positive words and primary visual cortex volume. The findings indicate that the neural areas subserving memory for emotion-laden information encompass posterior brain areas, including the cerebellum, and that memory for emotion-laden information may be driven by cognitive control functions.

Age-Related Changes in the Processing of Emotional Faces in a Dual-Task Paradigm

Background/ Study Context: Age-related changes appear to affect the ability to identify emotional facial expressions in dual-task conditions (i.e., while simultaneously performing a second visual task). The level of interference generated by the secondary task depends on the phase of emotional processing affected by the interference and the nature of the secondary task. The aim of the present study was to investigate the effect of these variables on age-related changes in the processing of emotional faces.

METHODS

The identification of emotional facial expressions (EFEs) was assessed in a dual-task paradigm using the following variables: (a) the phase during which interference was applied (encoding vs. retrieval phase); and (b) the nature of the interfering stimulus (visuospatial vs. verbal). The sample population consisted of 24 healthy aged adults (mean age = 75.38) and 40 younger adults (mean age = 26.90). The accuracy of EFE identification was calculated for all experimental conditions.

RESULTS

Consistent with our hypothesis, the performance of the older group was poorer than that of the younger group in all experimental conditions. Dual-task performance was poorer when the interference occurred during the encoding phase of emotional face processing and when both tasks were of the same nature (i.e., when the experimental condition was more demanding in terms of attention).

CONCLUSIONS

These results provide empirical evidence of age-related deficits in the identification of emotional facial expressions, which may be partially explained by the impairment of cognitive resources specific to this task. These findings may account for the difficulties experienced by the elderly during social interactions that require the concomitant processing of emotional and environmental information.

Age-related emotional bias in processing two emotionally valenced tasks

Previous studies suggest that older adults process positive emotions more efficiently than negative emotions, whereas younger adults show the reverse effect. We examined whether this age-related difference in emotional bias still occurs when attention is engaged in two emotional tasks. We used a psychological refractory period paradigm and varied the emotional valence of Task 1 and Task 2. In both experiments, Task 1 was emotional face discrimination (happy vs. angry faces) and Task 2 was sound discrimination (laugh, punch, vs. cork pop in Experiment 1 and laugh vs. scream in Experiment 2). The backward emotional correspondence effect for positively and negatively valenced Task 2 on Task 1 was measured. In both experiments, younger adults showed a backward correspondence effect from a negatively valenced Task 2, suggesting parallel processing of negatively valenced stimuli. Older adults showed similar negativity bias in Experiment 2 with a more salient negative sound ("scream" relative to "punch"). These results are consistent with an arousal-bias competition model [Mather and Sutherland (Perspectives in Psychological Sciences 6:114-133, 2011)], suggesting that emotional arousal modulates top-down attentional control settings (emotional regulation) with age.

On the importance of Task 1 and error performance measures in PRP dual-task studies

The psychological refractory period (PRP) paradigm is a dominant research tool in the literature on dual-task performance. In this paradigm a first and second component task (i.e., Task 1 and Task 2) are presented with variable stimulus onset asynchronies (SOAs) and priority to perform Task 1. The main indicator of dual-task impairment in PRP situations is an increasing Task 2-RT with decreasing SOAs. This impairment is typically explained with some task components being processed strictly sequentially in the context of the prominent central bottleneck theory. This assumption could implicitly suggest that processes of Task 1 are unaffected by Task 2 and bottleneck processing, i.e., decreasing SOAs do not increase reaction times (RTs) and error rates of the first task. The aim of the present review is to assess whether PRP dual-task studies included both RT and error data presentations and statistical analyses and whether studies including both data types (i.e., RTs and error rates) show data consistent with this assumption (i.e., decreasing SOAs and unaffected RTs and/or error rates in Task 1). This review demonstrates that, in contrast to RT presentations and analyses, error data is underrepresented in a substantial number of studies. Furthermore, a substantial number of studies with RT and error data showed a statistically significant impairment of Task 1 performance with decreasing SOA. Thus, these studies produced data that is not primarily consistent with the strong assumption that processes of Task 1 are unaffected by Task 2 and bottleneck processing in the context of PRP dual-task situations; this calls for a more careful report and analysis of Task 1 performance in PRP studies and for a more careful consideration of theories proposing additions to the bottleneck assumption, which are sufficiently general to explain Task 1 and Task 2 effects.

Happily distracted: mood and a benefit of attention dysregulation in older adults

Positive mood states are believed to broaden the focus of attention in younger adults, but it is unclear whether the same is true for older adults. Here we examined one consequence of broader attention that has been shown in young adults: that memory for distraction is greater for those in a positive mood. In the current study, positive and neutral moods were induced in older adults (M = 67.9) prior to a 1-back task in which participants were instructed to attend to relevant pictures and ignore distracting words. Following a 10-min filled interval, participants performed a word fragment completion task that tested implicit memory for the distracting words from the 1-back task. Older adults in the positive mood group showed greater implicit memory for previous distraction compared to those in the neutral mood group. These findings suggest that affect influences the ability to regulate attention in a similar manner for younger and older adults.

Impact of negative emotion on the neural correlates of long-term recognition in younger and older adults

Some studies have suggested that the memory advantage for negative emotional information over neutral information (“negativity effect”) is reduced in aging. Besides the fact that most findings are based on immediate retrieval, the neural underpinnings of long-term emotional memory in aging have so far not been investigated. To address these issues, we assessed recognition of neutral and negative scenes after 1- and 3-week retention intervals in younger and older adults using functional magnetic resonance imaging. We further used an event-related design in order to disentangle successful, false, and true recognition. This study revealed four key findings: (1) increased retention interval induced an increased rate of false recognitions for negative scenes, canceling out the negativity effect (present for hit rates only) on discrimination in both younger and older adults; (2) in younger, but not older, adults, reduced activity of the medial temporal lobe was observed over time for neutral scenes, but not for negative scenes, where stable or increased activity was seen; (3) engagement of amygdala (AMG) was observed in older adults after a 3-week delay during successful recognition of negative scenes (hits vs. misses) in comparison with neutral scenes, which may indicate engagement of automatic processes, but engagement of ventrolateral prefrontal cortex was unrelated to AMG activity and performance; and (4) after 3 weeks, but not after 1 week, true recognition of negative scenes was characterized by more activity in left hippocampus and lateral occipito-temporal regions (hits vs. false alarms). As these regions are known to be related to consolidation mechanisms, the observed pattern may indicate the presence of delayed consolidation of true memories. Nonetheless, older adults’ low performance in discrimination of negative scenes could reflect the fact that overall, after long delays of retention, they rely more on general information rather than on perceptual detail in making recognition judgments.