Physical Salience and Value-Driven Salience Operate through Different Neural Mechanisms to Enhance Attentional Selection

Different neural mechanisms for nonsalient trained stimuli and physically salient stimuli in visual processing

Previous studies have shown that nonsalient trained stimuli could capture attention and would be actively suppressed when served as distractors. However, it was unclear whether nonsalient trained stimuli and physically salient stimuli operate through the same attentional neural mechanism. In the current study, we investigated this question by recording event-related potentials (ERPs) of searching for the two stimuli separately after matching the difficulty. The present results provided additional evidence for the function of the suppression in that it may terminate a shift of attention. For the N1 component, the nonsalient trained stimuli had a shorter latency and larger amplitude than the physically salient stimuli whether presented as targets or distractors. It indicated that the nonsalient trained stimuli had an earlier sensory processing and greater visual attention orienting. The N2 posterior-contralateral (N2pc) amplitude of the physically salient target was larger than the nonsalient trained target. This suggested that physically salient stimuli had a stronger ability to capture attention. However, when they presented as distractors, only the nonsalient trained stimuli could elicit the PD component. Therefore, active suppression of the physically salient stimuli was more difficult than the nonsalient trained stimulus with the same difficulty. For the P3 component, the amplitude of the physically salient stimuli was larger than that of the nonsalient trained stimuli, both as targets and distractors, which indicated that the top-down controlled process of outcome evaluation for the salient triangle was stronger. Overall, these results suggested that they were processed via different neural mechanisms in the early sensory processing, attentional selection, active suppression, and the outcome-evaluation process.

Reward delays quitting in visual search

Reward motivates goal-directed behaviors, leading to faster reaction time (RT) and lower error rate in searching for a target in the reward condition than in the no-reward condition in target-discrimination tasks. However, it is unclear how reward influences target detection in which participants are required to judge whether a predesignated target is present or absent. Here, we asked participants to complete a target-detection search task in which the color of the search array indicated the reward availability of the current trial. Correct and faster (than a baseline) responses would be rewarded if the search array had the reward-related color. In Experiments 1A and 1B, the target was presented in 50% of the trials. Experiment 1B had the same design as Experiment 1A, except that different baselines were set for the target-present and target-absent conditions. In Experiment 2, the proportion of target presence was manipulated to be high (80%), moderate (50%), or low (20%) in different blocks of stimuli. Results showed that, across all the experiments, participants responded faster and made fewer errors in the reward than in the no-reward condition when the target was present. However, this facilitatory effect was reversed when the target was absent, showcasing a reward-induced interference. The signal detection analysis suggested that reward biased the report criterion to the "yes" response. These findings demonstrate that the impact of reward on goal-directed behavior can be detrimental and reward prolongs the search process by rendering participants reluctant to say "no" in visual search termination.

Evaluating individual differences in rewarded Stroop performance: reliability and associations with self-report measures

In three separate experiments, we examined the reliability of and relationships between self-report measures and behavioral response time measures of reward sensitivity. Using a rewarded-Stroop task we showed that reward-associated, but task-irrelevant, information interfered with task performance (MIRA) in all three experiments, but individual differences in MIRA were unreliable both within-session and over a period of approximately 4 weeks, providing clear evidence that it is not a good individual differences measure. In contrast, when the task-relevant information was rewarded, individual differences in performance benefits were remarkably reliable, even when examining performance one year later, and with a different version of a rewarded Stroop task. Despite the high reliability of the behavioral measure of reward responsiveness, behavioral reward responsiveness was not associated with self-reported reward responsiveness scores using validated questionnaires but was associated with greater self-reported self-control. Results are discussed in terms of what is actually being measured in the rewarded Stroop task.

General deficits of attentional inhibition in high trait anxiety: ERP evidence

Behavioral evidence shows that individuals with high trait anxiety tend to be distracted by irrelevant stimulation not only for threat-related stimuli but also for non-emotional neutral stimuli. These findings suggest that there may be a general deficit of attentional control in trait anxiety. However, the neural mechanism underlying the anxiety-related deficit in attentional control, especially inhibition function, is still unclear. Here, we examined the attentional processing of the non-emotional neutral distractor on 66 young adults with different levels of trait anxiety, using the ERP indices of attentional selection (N2pc) and top-down inhibition (Pd) in a search task with geometric stimuli. We found that the distractor-evoked N2pc amplitude did not vary with anxiety levels, but increased anxiety was associated with smaller Pds (i.e. worse inhibition). Besides, delayed attentional selection of targets was associated with higher anxiety levels. These correlations of trait anxiety remained significant even after controlling for state anxiety, and state anxiety did not affect the attentional processing of distractors and targets, suggesting that trait anxiety, not current anxiety, affects attentional function. Our findings clarify the mechanism underlying the general attentional deficits in trait anxiety, e.g. reduced distractor inhibition and delayed target selection.

Reward and loss incentives improve spatial working memory by shaping trial-by-trial posterior frontoparietal signals

Integrating motivational signals with cognition is critical for goal-directed activities. The mechanisms that link neural changes with motivated working memory continue to be understood. Here, we tested how externally cued and non-cued (internally represented) reward and loss impact spatial working memory precision and neural circuits in human subjects using fMRI. We translated the classic delayed-response spatial working memory paradigm from non-human primate studies to take advantage of a continuous numeric measure of working memory precision, and the wealth of translational neuroscience yielded by these studies. Our results demonstrated that both cued and non-cued reward and loss improved spatial working memory precision. Visual association regions of the posterior prefrontal and parietal cortices, specifically the precentral sulcus (PCS) and intraparietal sulcus (IPS), had increased BOLD signal during incentivized spatial working memory. A subset of these regions had trial-by-trial increases in BOLD signal that were associated with better working memory precision, suggesting that these regions may be critical for linking neural signals with motivated working memory. In contrast, regions straddling executive networks, including areas in the dorsolateral prefrontal cortex, anterior parietal cortex and cerebellum displayed decreased BOLD signal during incentivized working memory. While reward and loss similarly impacted working memory processes, they dissociated during feedback when money won or avoided in loss was given based on working memory performance. During feedback, the trial-by-trial amount and valence of reward/loss received was dissociated amongst regions such as the ventral striatum, habenula and periaqueductal gray. Overall, this work suggests motivated spatial working memory is supported by complex sensory processes, and that the IPS and PCS in the posterior frontoparietal cortices may be key regions for integrating motivational signals with spatial working memory precision.

On the Influence of Spatial and Value Attentional Cues Across Individuals

The visual world provides a myriad of cues that can be used to direct information processing. How does the brain integrate predictive information from disparate sources to modify visual priorities, and are combination strategies consistent across individuals? Previous evidence shows that cues predictive of the value of a visually guided task (incentive value) and cues that signal where targets may occur (spatial certainty) act independently to bias attention. Anticipatory accounts propose that both cues are encoded into an attentional priority map, whereas the counterfactual account argues that incentive value cues instead induce a reactive encoding of losses based on the direction of attention. We adjudicate between these alternatives and further determine whether there are individual differences in how attentional cues are encoded. 149 participants viewed two coloured placeholders that specified the potential value of correctly identifying an imminent target. Prior to the target’s presentation, an endogenous spatial cue indicated the target’s likely location. The anticipatory and counterfactual accounts were used to motivate parametric regressors that were compared in their explanatory power of the data, at the group level and on data stratified by a clustering algorithm. Clustering revealed 2 subtypes; whereas all individuals use spatial certainty cues a subset does not use incentive value cues. When incentive value cues are used their influence reflects a counterfactual loss function. The data support the counterfactual account and show that theories of motivated attention must account for the non-uniform influence of incentive value on visual priorities.

Using Neural Networks to Uncover the Relationship between Highly Variable Behavior and EEG during a Working Memory Task with Distractors

Value-driven attention capture (VDAC) occurs when previously rewarded stimuli capture attention and impair goal-directed behavior. In a working memory (WM) task with VDAC-related distractors, we observe behavioral variability both within and across individuals. Individuals differ in their ability to maintain relevant information and ignore distractions. These cognitive components shift over time with changes in motivation and attention, making it difficult to identify underlying neural mechanisms of individual differences. In this study, we develop the first participant-specific feedforward neural network models of reaction time from neural data during a VDAC WM task. We used short epochs of electroencephalography (EEG) data from 16 participants to develop the feedforward neural network (NN) models of RT aimed at understanding both WM and VDAC. Using general linear models (GLM), we identified 20 EEG features to predict RT across participants (r=0.53±0.08). The linear model was compared to the NN model, which improved the predicted trial-by-trial RT for all participants (r=0.87±0.04). We found that right frontal gamma-band activity and fronto-posterior functional connectivity in the alpha, beta, and gamma bands explain individual differences. Our study shows that NN models can link neural activity to highly variable behavior and can identify potential new targets for neuromodulation interventions.

Reward magnitude enhances early attentional processing of auditory stimuli

Reward associations are known to shape the brain's processing of visual stimuli, but relatively less is known about how reward associations impact the processing of auditory stimuli. We leveraged the high-temporal resolution of electroencephalography (EEG) and event-related potentials (ERPs) to investigate the influence of low- and high-magnitude stimulus-reward associations in an auditory oddball task. We associated fast, correct detection of certain auditory target stimuli with larger monetary rewards, and other auditory targets with smaller rewards. We found enhanced attentional processing of the more highly rewarded target stimuli, as evidenced by faster behavioral detection of those stimuli compared with lower-rewarded stimuli. Neurally, higher-reward associations enhanced the early sensory processing of auditory targets. Targets associated with higher-magnitude rewards had higher amplitude N1 and mismatch negativity (MMN) ERP components than targets associated with lower-magnitude rewards. Reward did not impact the latency of these early components. Higher-reward magnitude also decreased the latency and increased the amplitude of the longer-latency P3 component, suggesting that reward also can enhance the final processing stages of auditory target stimuli. These results provide insight into how the sensory and attentional neural processing of auditory stimuli is modulated by stimulus-reward associations and the magnitude of those associations, with higher-magnitude reward associations yielding enhanced auditory processing at both early and late stages compared with lower-magnitude reward associations.

Epidermal growth factor receptor-mutated lung adenocarcinoma diagnosed from endometrial polyp metastasis: A case report and literature review

Endometrial metastasis from the lung primary remains is rare. Moreover, the literature only contains case reports of endometrial metastasis from the primary lung cancer. An 83-year-old female patient presented with postmenopausal uterine bleeding and anemia. Endometrial thickening was detected using transvaginal ultrasound and endometrial curettage was performed. Histopathology revealed adenocarcinoma infiltration on an endometrial polyp surface. On histologic examination, high-grade serous carcinoma and clear cell carcinoma diagnoses were initially considered. The tumor cells were immunohistochemically negative for Wilms’ tumor 1 and wild-type for p53 expression; however, it was positive for Napsin A. Primary lung adenocarcinoma (LUAD) metastasis was also included in the differential diagnosis. Thyroid transcription factor 1 was positive, whereas paired box gene 8 (Pax8) was negative in tumor cells. Primary LUAD metastasis was diagnosed since a lung mass was radiologically confirmed. Furthermore, epidermal growth factor receptor-exon 19 mutation was detected by molecular analysis. In addition to the clinical and morphological features, this case report emphasizes the importance of multiple immunohistochemical panel applications for the correct diagnosis.

Temporal preparation accelerates spatial selection by facilitating bottom-up processing

Temporal preparation facilitates spatial selection in visual search. This selection benefit has not only been observed for targets, but also for task-irrelevant, salient distractors. This result suggests that temporal preparation influences bottom-up salience in spatial selection. To test this assumption, we conducted an event-related-potential (ERP) study in which we measured the joint effect of temporal preparation and target salience on the N2pc as an index of spatial selection and the N1 as an index of perceptual discrimination. To manipulate target salience, we employed two different setsizes (i.e., a small or large number of homogeneous distractors). To manipulate temporal preparation, we presented a warning signal before the search display and we varied the length of the interval (foreperiod) between warning signal and search display in different blocks of trials (constant foreperiod paradigm). Replicating previous results, we observed that the N1 and the N2pc arose earlier in case of good temporal preparation. Importantly, the beneficial effect on the N2pc onset latency was stronger when the target salience was initially low (i.e., small setsize). This result provides evidence that temporal preparation influences bottom-up processing and, thereby, facilitates spatial selection.

The diachronic account of attentional selectivity

Many models of attention assume that attentional selection takes place at a specific moment in time that demarcates the critical transition from pre-attentive to attentive processing of sensory input. We argue that this intuitively appealing standard account of attentional selectivity is not only inaccurate, but has led to substantial conceptual confusion. As an alternative, we offer a 'diachronic' framework that describes attentional selectivity as a process that unfolds over time. Key to this view is the concept of attentional episodes, brief periods of intense attentional amplification of sensory representations that regulate access to working memory and response-related processes. We describe how attentional episodes are linked to earlier attentional mechanisms and to recurrent processing at the neural level. We review studies that establish the existence of attentional episodes, delineate the factors that determine if and when they are triggered, and discuss the costs associated with processing multiple events within a single episode. Finally, we argue that this framework offers new solutions to old problems in attention research that have never been resolved. It can provide a unified and conceptually coherent account of the network of cognitive and neural processes that produce the goal-directed selectivity in perceptual processing that is commonly referred to as 'attention'.

The past, present, and future of selection history

The last ten years of attention research have witnessed a revolution, replacing a theoretical dichotomy (top-down vs. bottom-up control) with a trichotomy (biased by current goals, physical salience, and selection history). This third new mechanism of attentional control, selection history, is multifaceted. Some aspects of selection history must be learned over time whereas others reflect much more transient influences. A variety of different learning experiences can shape the attention system, including reward, aversive outcomes, past experience searching for a target, target‒non-target relations, and more. In this review, we provide an overview of the historical forces that led to the proposal of selection history as a distinct mechanism of attentional control. We then propose a formal definition of selection history, with concrete criteria, and identify different components of experience-driven attention that fit within this definition. The bulk of the review is devoted to exploring how these different components relate to one another. We conclude by proposing an integrative account of selection history centered on underlying themes that emerge from our review.

The Impact of Error-Consequence Severity on Cue Processing in Importance-Biased Prospective Memory

Prospective memory (PM) enables people to remember to complete important tasks in the future. Failing to do so can result in consequences of varying severity. Here, we investigated how PM error-consequence severity impacts the neural processing of relevant cues for triggering PM and the ramification of that processing on the associated prospective task performance. Participants role-played a cafeteria worker serving lunches to fictitious students and had to remember to deliver an alternative lunch to students (as PM cues) who would otherwise experience a moderate or severe aversive reaction. Scalp-recorded, event-related potential (ERP) measures showed that the early-latency frontal positivity, reflecting the perception-based neural responses to previously learned stimuli, did not differ between the severe versus moderate PM cues. In contrast, the longer-latency parietal positivity, thought to reflect full PM cue recognition and post-retrieval processes, was elicited earlier by the severe than the moderate PM cues. This faster instantiation of the parietal positivity to the severe-consequence PM cues was then followed by faster and more accurate behavioral responses. These findings indicate how the relative importance of a PM can be neurally instantiated in the form of enhanced and faster PM-cue recognition and processing and culminate into better PM.

μ Opioid Antagonist Naltrexone Partially Abolishes the Antidepressant Placebo Effect and Reduces Orbitofrontal Cortex Encoding of Reinforcement

BACKGROUND

Like placebo analgesia, the antidepressant placebo effect appears to involve cortical and subcortical endogenous opioid signaling, yet the mechanism through which opioid release affects mood remains unclear. The orbitofrontal cortex (OFC)-which integrates various attributes of a stimulus to predict associated outcomes-has been implicated in placebo effects and is rich in μ opioid receptors. We hypothesized that naltrexone blockade of μ opioid receptors would blunt OFC-dependent antidepressant placebo effects.

METHODS

Twenty psychotropic-free patients with major depressive disorder completed a randomized, double-blind, placebo-controlled crossover study of 1 oral dose of 50 mg of naltrexone or matching placebo immediately before completing 2 sessions of the antidepressant placebo functional magnetic resonance imaging task. This task manipulates placebo-associated expectancies and their reinforcement while assessing expected and actual mood improvement.

RESULTS

Behaviorally, manipulations of antidepressant placebo expectancies and their reinforcement had positive, interactive effects on participants' expectancy and mood ratings. The high-expectancy condition recruited the dorsolateral and ventrolateral prefrontal cortex, as well as dorsal attention stream regions. Interestingly, increased dorsolateral and ventrolateral prefrontal cortex brain responses appeared to attenuate the antidepressant placebo effect. The administration of 1 oral dose of naltrexone, compared with placebo, partially abolished the interaction of the expectancy and reinforcement manipulation on mood and blocked reinforcement-induced responses in the right central OFC.

CONCLUSIONS

Our results show preliminary evidence for the role of μ opioid central OFC modulation in antidepressant placebo effects by positively biasing the value of placebo based on reinforcement and enhancing subsequent hedonic experiences.

Disruptions of Sustained Spatial Attention Can Be Resistant to the Distractor's Prior Reward Associations

Attention can be involuntarily biased toward reward-associated distractors (value-driven attentional capture, VDAC). Yet past work has primarily demonstrated this distraction phenomenon during a particular set of circumstances: transient attentional orienting to potentially relevant stimuli occurring in our visual environment. Consequently, it is not well-understood if reward-based attentional capture can occur under other circumstances, such as during sustained visuospatial attention. Using EEG, we investigated whether associating transient distractors with reward value would increase their distractibility and lead to greater decrements in concurrent sustained spatial attention directed elsewhere. Human participants learned to associate three differently colored, laterally presented squares with rewards of varying magnitude (zero, small, and large). These colored squares were then periodically reintroduced as distractors at the same lateral locations during a demanding sustained-attention rapid-serial-visual-presentation (RSVP) task at the midline. Behavioral and neural evidence indicated that participants had successfully learned and maintained the reward associations to the distractors. During the RSVP task, consistent with prior work, we found that the distractors generated dips in the instantaneous amplitude of the steady-state visual evoked potentials (SSVEPs) elicited by the midline RSVP stimuli, indicating that the distractors were indeed transiently disrupting sustained spatial attention. Contrary to our hypotheses, however, the magnitude of this dip did not differ by the magnitude of the distractor’s reward associations. These results indicate that while sustained spatial attention can be impaired by the introduction of distractors at another location, the main distraction process is resistant to the distractors’ reward associations, thus providing evidence of an important boundary condition to value-driven attentional capture.

Gotcha: Working memory prioritization from automatic attentional biases

Attention is an important resource for prioritizing information in working memory (WM), and it can be deployed both strategically and automatically. Most research investigating the relationship between WM and attention has focused on strategic efforts to deploy attentional resources toward remembering relevant information. However, such voluntary attentional control represents a mere subset of the attentional processes that select information to be encoded and maintained in WM (Theeuwes, Journal of Cognition, 1[1]: 29, 1-15, 2018). Here, we discuss three ways in which information becomes prioritized automatically in WM-physical salience, statistical learning, and reward learning. This review integrates findings from perception and working memory studies to propose a more sophisticated understanding of the relationship between attention and working memory.

Multiregional communication and the channel modulation hypothesis

Multiregional communication is important to understanding the brain mechanisms supporting complex behaviors. Work in animals and human subjects shows that multiregional communication plays significant roles in cognitive function and is associated with neurological and neuropsychiatric disorders of brain function. Recent experimental advances enable empirical tests of the mechanisms of multiregional communication. Recent mechanistic insights into brain network function also suggest new therapies to treat disordered brain networks. Here, we discuss how to use the concept of communication channel modulation can help define and constrain what we mean by multiregional communication. We discuss behavioral and neurophysiological evidence for multiregional channels modulation. We then consider the role of causal manipulations and their implications for developing novel therapies based on multiregional communication.