Age-related changes in selective attention and perceptual load during visual search

Real-Time fMRI Neurofeedback Training of Selective Attention in Older Adults

BACKGROUND

Selective attention declines with age, due to age-related functional changes in dorsal anterior cingulate cortex (dACC). Real-time functional magnetic resonance imaging (rtfMRI) neurofeedback has been used in young adults to train volitional control of brain activity, including in dACC.

METHODS

For the first time, this study used rtfMRI neurofeedback to train 19 young and 27 older adults in volitional up- or down-regulation of bilateral dACC during a selective attention task.

RESULTS

Older participants in the up-regulation condition (experimental group) showed greater reward points and dACC BOLD signal across training sessions, reflective of neurofeedback training success; and faster reaction time and better response accuracy, suggesting behavioral benefits on selective attention. These effects were not observed for older participants in the down-regulation condition (inverse condition control group), supporting specificity of volitional dACC up-regulation training in older adults. These effects were, unexpectedly, also not observed for young participants in the up-regulation condition (age control group), perhaps due to a lack of motivation to continue the training.

CONCLUSIONS

These findings provide promising first evidence of functional plasticity in dACC in late life via rtfMRI neurofeedback up-regulation training, enhancing selective attention, and demonstrate proof of concept of rtfMRI neurofeedback training in cognitive aging.

Attention-dependent coupling with forebrain and brainstem neuromodulatory nuclei changes across the lifespan

Attentional states continuously reflect the predictability and uncertainty in one's environment having important consequences for learning and memory. Beyond well known cortical contributions, rapid shifts in attention are hypothesized to also originate from deep nuclei, such as the basal forebrain (BF) and locus coeruleus (LC) neuromodulatory systems. These systems are also the first to change with aging. Here we characterized the interplay between these systems and their regulation of afferent targets - the hippocampus (HPC) and posterior cingulate cortex (PCC) - across the lifespan. To examine the role of attentional salience on task-dependent functional connectivity, we used a target-distractor go/no go task presented during functional MRI. In younger adults, BF coupling with the HPC, and LC coupling with the PCC, increased with behavioral relevance (targets vs distractors). Although the strength and presence of significant regional coupling changed in middle age, the most striking change in network connectivity was in old age, such that in older adults BF and LC coupling with their cortical afferents was largely absent and replaced by stronger interconnectivity between LC-BF nuclei. Overall rapid changes in attention related to behavioral relevance revealed distinct roles of subcortical neuromodulatory systems. The pronounced changes in functional network architecture across the lifespan suggest a decrease in these distinct roles, with deafferentation of cholinergic and noradrenergic systems associated with a shift towards mutual support during attention guided to external stimuli.

Disentangling listening effort and memory load beyond behavioural evidence: Pupillary response to listening effort during a concurrent memory task

Recent research has demonstrated that pupillometry is a robust measure for quantifying listening effort. However, pupillary responses in listening situations where multiple cognitive functions are engaged and sustained over a period of time remain hard to interpret. This limits our conceptualisation and understanding of listening effort in realistic situations, because rarely in everyday life are people challenged by one task at a time. Therefore, the purpose of this experiment was to reveal the dynamics of listening effort in a sustained listening condition using a word repeat and recall task. Words were presented in quiet and speech-shaped noise at different signal-to-noise ratios (SNR): 0dB, 7dB, 14dB and quiet. Participants were presented with lists of 10 words, and required to repeat each word after its presentation. At the end of the list, participants either recalled as many words as possible or moved on to the next list. Simultaneously, their pupil dilation was recorded throughout the whole experiment. When only word repeating was required, peak pupil dilation (PPD) was bigger in 0dB versus other conditions; whereas when recall was required, PPD showed no difference among SNR levels and PPD in 0dB was smaller than repeat-only condition. Baseline pupil diameter and PPD followed different variation patterns across the 10 serial positions within a block for conditions requiring recall: baseline pupil diameter built up progressively and plateaued in the later positions (but shot up when listeners were recalling the previously heard words from memory); PPD decreased at a pace quicker than in repeat-only condition. The current findings demonstrate that additional cognitive load during a speech intelligibility task could disturb the well-established relation between pupillary response and listening effort. Both the magnitude and temporal pattern of task-evoked pupillary response differ greatly in complex listening conditions, urging for more listening effort studies in complex and realistic listening situations.

Response-level processing during visual feature search: Effects of frontoparietal activation and adult age

Previous research suggests that feature search performance is relatively resistant to age-related decline. However, little is known regarding the neural mechanisms underlying the age-related constancy of feature search. In this experiment, we used a diffusion decision model of reaction time (RT), and event-related functional magnetic resonance imaging (fMRI) to investigate age-related differences in response-level processing during visual feature search. Participants were 80 healthy, right-handed, community-dwelling individuals, 19–79 years of age. Analyses of search performance indicated that targets accompanied by response-incompatible distractors were associated with a significant increase in the nondecision-time (t0) model parameter, possibly reflecting the additional time required for response execution. Nondecision time increased significantly with increasing age, but no age-related effects were evident in drift rate, cautiousness (boundary separation, a), or in the specific effects of response compatibility. Nondecision time was also associated with a pattern of activation and deactivation in frontoparietal regions. The relation of age to nondecision time was indirect, mediated by this pattern of frontoparietal activation and deactivation. Response-compatible and -incompatible trials were associated with specific patterns of activation in the medial and superior parietal cortex, and frontal eye field, but these activation effects did not mediate the relation between age and search performance. These findings suggest that, in the context of a highly efficient feature search task, the age-related influence of frontoparietal activation is operative at a relatively general level, which is common to the task conditions, rather than at the response level specifically.

Visual Acuity does not Moderate Effect Sizes of Higher-Level Cognitive Tasks

BACKGROUND/STUDY CONTEXT

Declining visual capacities in older adults have been posited as a driving force behind adult age differences in higher-order cognitive functions (e.g., the "common cause" hypothesis of Lindenberger & Baltes, 1994, Psychology and Aging, 9, 339-355). McGowan, Patterson, and Jordan (2013, Experimental Aging Research, 39, 70-79) also found that a surprisingly large number of published cognitive aging studies failed to include adequate measures of visual acuity. However, a recent meta-analysis of three studies (La Fleur and Salthouse, 2014, Psychonomic Bulletin & Review, 21, 1202-1208) failed to find evidence that visual acuity moderated or mediated age differences in higher-level cognitive processes. In order to provide a more extensive test of whether visual acuity moderates age differences in higher-level cognitive processes, we conducted a more extensive meta-analysis of topic.

METHODS

Using results from 456 studies, we calculated effect sizes for the main effect of age across four cognitive domains (attention, executive function, memory, and perception/language) separately for five levels of visual acuity criteria (no criteria, undisclosed criteria, self-reported acuity, 20/80-20/31, and 20/30 or better).

RESULTS

As expected, age had a significant effect on each cognitive domain. However, these age effects did not further differ as a function of visual acuity criteria.

CONCLUSION

The current meta-analytic, cross-sectional results suggest that visual acuity is not significantly related to age group differences in higher-level cognitive performance-thereby replicating La Fleur and Salthouse (2014). Further efforts are needed to determine whether other measures of visual functioning (e.g., contrast sensitivity, luminance) affect age differences in cognitive functioning.

Age-related Differences in Attentional Failures during Driving

Older drivers experience increasing risks of vehicle crashes. This increase in crash risks has been associated with age-related declines in attention. To assess attentional failures during driving, we develop a self-report measure, the Attentional Failures during Driving Questionnaire (AFDQ). In this paper, we describe the development of the questionnaire and our preliminary effort to examine its reliability and validity via an online survey. The results demonstrated a high level of internal consistency of the questionnaire. In addition, we found that self-reported attentional failures during driving are not only associated with self-reported attentional and cognitive failures during other daily activities, but also related to unsafe driving behaviors and self-efficacy in driving. Our results also showed significant age-related differences in the AFDQ score: old-old drivers (age 75+) reported a higher level of attentional failures during driving than middle-aged drivers (age 25-64) and young-old drivers (age 65-74). These preliminary results indicate the potential use of AFDQ as a measure of attentional performance during driving for older drivers.

Attention and working memory in elderly: the influence of a distracting environment

The present work investigated the effect of a distracting environment in the performance of attentional and working memory (WM) tasks in elderly participants. To this end, forty elderly performed two attentional tasks (simple reaction time and go/no-go tasks), and three WM tasks (arithmetic, memory for digits and sequences of letters and numbers). Each participant performed the tasks in a distracting and a non-distracting environment, with an interval of 14-21 days between sessions. The results revealed better performance in the attentional tasks when these were done in the non-distracting environment, as compared to when they were done in the distracting environment. Specifically, participants provided more accurate responses, fewer false alarms and omissions when responding in the non-distracting environment than when responding in the distracting environment. Participants were also faster at providing correct responses in the go/no-go task when it was performed in the non-distracting environment. As for the memory tasks, the effect of type of environment was significant only in the memory for digits in a forward direction task. Our data suggest the need to consider the potential damaging consequences of distracting environments when the elderly have to perform tasks that demand their attention. Specific examples of such situations are presented in the discussion (e.g., distracting effect of environment on medical and on psychological evaluations).

Response-specific slowing in older age revealed through differential stimulus and response effects on P300 latency and reaction time

Older age produces numerous changes in cognitive processes, including slowing in the rate of mental processing speed. There has been controversy over the past three decades about whether this slowing is generalized or process-specific. A growing literature indicates that it is process-specific and suggests it is most dramatic at the interface where a stimulus input is translated into a response output. We tested this hypothesis using a task in which young and older adult males made either compatible or incompatible responses to the word LEFT or RIGHT shown briefly and variously located in a 4 row × 6 column matrix surrounded by # signs or by letters chosen randomly from the sets A-G or A-Z. Processing speed was measured using P300 latency and reaction time. Experimental effects on these two measures provided support for the hypothesis in revealing that stimulus identification processes were preserved, whereas processes related to translating a stimulus input into a designated response output and then selecting that response were compromised in the elderly.

Aging and repeated thought suppression success

Intrusive thoughts and attempts to suppress them are common, but while suppression may be effective in the short-term, it can increase thought recurrence in the long-term. Because intentional suppression involves controlled processing, and many aspects of controlled processing decline with age, age differences in thought suppression outcomes may emerge, especially over repeated thought suppression attempts as cognitive resources are expended. Using multilevel modeling, we examined age differences in reactions to thought suppression attempts across four thought suppression sequences in 40 older and 42 younger adults. As expected, age differences were more prevalent during suppression than during free monitoring periods, with younger adults indicating longer, more frequent thought recurrences and greater suppression difficulty. Further, younger adults' thought suppression outcomes changed over time, while trajectories for older adults' were relatively stable. Results are discussed in terms of older adults' reduced thought recurrence, which was potentially afforded by age-related changes in reactive control and distractibility.

Perceptual load, voluntary attention, and aging: an event-related potential study

The locus of attentional selection is known to vary with perceptual load (Lavie et al., 2004). Under voluntary attention, perceptual load modulates selective visual processing at an early cortical stage, as reflected in the posterior P1 and N1 components of the event-related potentials (ERPs). Adult aging also affects both behavioral and ERP signs of attentional selection. However, it is not known whether perceptual load modulates this relationship. Accordingly, in the present study ERPs were recorded in a voluntary attention task. Young and old participants were asked to discriminate the direction of a target line embedded within a display of four lines that appeared in the left or right visual field. Participants responded faster and more accurately to valid relative to invalid trials and to low-load relative to high-load condition. Older participants responded more slowly and with lower accuracy than young participants in all conditions. The amplitudes of the posterior contralateral P1 and N1 components in valid trials were larger than that in invalid trials in all conditions. N1 amplitude was larger under the high load condition than that in the low load condition. Moreover, in the high perceptual load condition, the old group had a larger N1 than the young group at contralateral sites. The findings suggest that under voluntary attention, perceptual load and aging modulates attentional selection at an early but not the earliest stage, during the N1 (120-200ms) time range. Increased N1 amplitude in older adults may reflect increased demands on target discrimination in high perceptual load.

Age-related reorganization of functional networks for successful conflict resolution: a combined functional and structural MRI study

Aging has readily observable effects on the ability to resolve conflict between competing stimulus attributes that are likely related to selective structural and functional brain changes. To identify age-related differences in neural circuits subserving conflict processing, we combined structural and functional MRI and a Stroop Match-to-Sample task involving perceptual cueing and repetition to modulate resources in healthy young and older adults. In our Stroop Match-to-Sample task, older adults handled conflict by activating a frontoparietal attention system more than young adults and engaged a visuomotor network more than young adults when processing repetitive conflict and when processing conflict following valid perceptual cueing. By contrast, young adults activated frontal regions more than older adults when processing conflict with perceptual cueing. These differential activation patterns were not correlated with regional gray matter volume despite smaller volumes in older than young adults. Given comparable performance in speed and accuracy of responding between both groups, these data suggest that successful aging is associated with functional reorganization of neural systems to accommodate functionally increasing task demands on perceptual and attentional operations.

The joint flanker effect: sharing tasks with real and imagined co-actors

The Eriksen flanker task (Eriksen and Eriksen in Percept Psychophys 16:143–149, 1974) was distributed among pairs of participants to investigate whether individuals take into account a co-actor’s S–R mapping even when coordination is not required. Participants responded to target letters (Experiment 1) or colors (Experiment 2) surrounded by distractors. When performing their part of the task next to another person performing the complementary part of the task, participants responded more slowly to stimuli containing flankers that were potential targets for their co-actor (incompatible trials), compared to stimuli containing identical, compatible, or neutral flankers. This joint Flanker effect also occurred when participants merely believed to be performing the task with a co-actor (Experiment 3). Furthermore, Experiment 4 demonstrated that people form shared task representations only when they perceive their co-actor as intentionally controlling her actions. These findings substantiate and generalize earlier results on shared task representations and advance our understanding of the basic mechanisms subserving joint action.

Targets and non-targets in the aging brain: A go/nogo event-related potential study

This study tested whether older adults show enhanced suppression of inappropriate processing of non-target information, as marked with the nogo-P3 event-related potential (ERP). Healthy younger and older adults were tested on a simple go/nogo task with visually presented numbers. Unlike in most of the previous studies, go and nogo stimuli were matched for frequency and conflict level in order to minimize the impact of task difficulty, probability monitoring, or conflict detection and resolution on the age-related ERP differences. Older adults showed slower go responses but a comparable accuracy to younger controls. The parietal go-P3 latency was also delayed with aging, while the central nogo-P3 was more pronounced in older adults than in younger controls. The amplitude of this component negatively correlated with go-RTs. In line with previous studies, this suggests that a partial response preparation to nogo events is strongly suppressed in older adults, especially faster ones.

Cardiovascular Health and Education as Sources of Individual Variability in Cognitive Aging Among African Americans

Objective: To examine the interrelated effects of cardiovascular health, education, and cognitive functioning in African Americans. Method: The present study utilized data from the Baltimore Study of Black Aging to examine whether (a) cardiovascular health and educational attainment predicted cognitive functioning, after controlling for age, and (b) there was an interaction between cardiovascular health and education in predicting cognitive functioning. Results: Using hierarchical regression analyses, results showed education was significant for all cognitive measures; however, cardiovascular health was significant for only three. Discussion: These findings suggest that although self-reported cardiovascular health contributes to variability in late life cognition in African Americans, education is a more universal predictor that should be further examined.

Neuroplasticity and cognitive aging: the scaffolding theory of aging and cognition

A recent proposal called the Scaffolding Theory of Cognitive Aging (STAC) postulates that functional changes with aging are part of a lifespan process of compensatory cognitive scaffolding that is an attempt to alleviate the cognitive declines associated with aging. Indeed, behavioral studies have shown that aging is associated with both decline as well as preservation of selective cognitive abilities. Similarly, neuroimaging studies have revealed selective changes in the aging brain that reflect neural decline as well as compensatory neural recruitment. While aging is associated with reductions in cortical thickness, white-matter integrity, dopaminergic activity, and functional engagement in posterior brain regions such as the hippocampus and occipital areas, there are compensatory increases in frontal functional engagement that correlate with better behavioral performance in older adults. In this review, we discuss these age-related behavioral and brain findings that support the STAC model of cognitive scaffolding and additionally integrate the findings on neuroplasticity as a compensatory response in the aging brain. As such, we also examine the impact of external experiences in facilitating neuroplasticity in older adults. Finally, having laid the foundation for STAC, we briefly describe a proposed intervention trial (The Synapse Program) designed to evaluate the behavioral and neural impact of engagement in lifestyle activities that facilitates successful cognitive scaffolding using a controlled experiment where older adult participants are randomly assigned to different conditions of engagement.

Preservation of crossmodal selective attention in healthy aging

The goal of the present study was to determine if older adults benefited from attention to a specific sensory modality in a voluntary attention task and evidenced changes in voluntary or involuntary attention when compared to younger adults. Suppressing and enhancing effects of voluntary attention were assessed using two cued forced-choice tasks, one that asked participants to localize and one that asked them to categorize visual and auditory targets. Involuntary attention was assessed using the same tasks, but with no attentional cues. The effects of attention were evaluated using traditional comparisons of means and Cox proportional hazards models. All analyses showed that older adults benefited behaviorally from selective attention in both visual and auditory conditions, including robust suppressive effects of attention. Of note, the performance of the older adults was commensurate with that of younger adults in almost all analyses, suggesting that older adults can successfully engage crossmodal attention processes. Thus, age-related increases in distractibility across sensory modalities are likely due to mechanisms other than deficits in attentional processing.

Age and culture modulate object processing and object-scene binding in the ventral visual area

Behavioral differences in the visual processing of objects and backgrounds as a function of cultural group are well documented. Recent neuroimaging evidence also points to cultural differences in neural activation patterns. Compared with East Asians, Westerners' visual processing is more object focused, and they activate neural structures that reflect this bias for objects. In a recent adaptation study, East Asian older adults showed an absence of an object-processing area but normal adaptation for background areas. In the present study, 75 young and old adults (half East Asian and half Western) were tested in an fMR-adaptation study to examine differences in object and background processing as well as object-background binding. We found equivalent background processing in the parahippocampal gyrus in all four groups, diminished binding processes in the hippocampus in elderly East Asians and Westerners, and diminished object processing in elderly versus young adults in the lateral occipital complex. Moreover, elderly East Asians showed significantly less adaptation response in the object areas than did elderly Westerners. These findings demonstrate the malleability of perceptual processes as a result of differences in cohort-specific experiences or in cultural exposure over time.

Effect of action video games on the spatial distribution of visuospatial attention

The authors investigated the effect of action gaming on the spatial distribution of attention. The authors used the flanker compatibility effect to separately assess center and peripheral attentional resources in gamers versus nongamers. Gamers exhibited an enhancement in attentional resources compared with nongamers, not only in the periphery but also in central vision. The authors then used a target localization task to unambiguously establish that gaming enhances the spatial distribution of visual attention over a wide field of view. Gamers were more accurate than nongamers at all eccentricities tested, and the advantage held even when a concurrent center task was added, ruling out a trade-off between central and peripheral attention. By establishing the causal role of gaming through training studies, the authors demonstrate that action gaming enhances visuospatial attention throughout the visual field.

Attentional disregulation: a benefit for implicit memory

The authors investigated the effect of age and time of testing on the ability to control attention and addressed the possibility that older adults' susceptibility to distraction may sometimes facilitate performance on a later cognitive task. Using a modification of a G. Rees, C. Russell, C. D. Frith, and J. Driver (1999) procedure, the authors asked the participants to make same or different judgments on line drawings superimposed with task-irrelevant letter strings. Memory for the distractors was subsequently tested with an implicit memory task. Both older and young adults demonstrated greater memory for distractors at nonoptimal times of day than at optimal times of day; however, older adults showed considerably better memory for the distractors than did young adults.

[Comparison of Work Ability Index and cognitive function tests]

The purpose of this study was to evaluate the effect of aging with regard to scores for certain cognitive function tests and WAI (Work Ability Index), and to examine the relationship between cognitive function test scores and work ability as measured by WAI. The subjects were 139 male employees of a factory producing steel plate, and their average age was 48.1 yr (SD 16.4). The WAI and cognitive function tests were conducted and valid scores were obtained from 134 subjects as to WAI, and from 88 subjects as to cognitive function tests. The subjects were divided into two groups: young workers (under 45 yr) and middle-aged to elderly workers (45 yr and over). The WAI scores of the two groups were compared, but no significant differences were observed. Nevertheless, for two WAI items, WAI-2 and WAI-7, the scores of the middle-aged to elderly worker group were significantly higher than those of the young worker group. In contrast, the scores for WAI-3 of the middle-aged to elderly group were significantly lower than those of the young worker group. The cognitive function test scores for the two groups were also compared. The scores for Working Memory test, Tracking test, and Sentence-to-sentence Comparison test of the middle-aged to elderly worker group were significantly lower than those of the younger group. Moreover, for the middle-aged to elderly worker group, the average WAI-3 scores for those with good cognitive function test results and those with poor cognitive function test results were compared, but there were no significant differences. This result shows that deterioration of physical function caused by aging is not related to deterioration of cognitive function caused by aging in the subjects of this study. The reason for this may be that the subjects are blue-collar workers, and thus cognitive functions are less important for their work.