Recent evidence suggests short-term exposure to particulate matter (PM) air pollution can impact brain function after a delay period. It is unknown whether effects are predominantly due to the olfactory or lung-brain pathways. In this study 26 adults (Mage = 27.7, SDage = 10.6) participated in four conditions. They were exposed to either high PM concentrations or clean air for one hour, using normal inhalation or restricted nasal inhalation and olfaction with a nose clip. Participants completed four cognitive tests before and four hours after exposure, assessing working memory, selective attention, emotion expression discrimination, and psychomotor vigilance. Results showed significant reductions in selective attention and emotion expression discrimination after enhanced PM versus clean air exposure. Air quality did not significantly impact psychomotor vigilance or working memory performance. Inhalation method did not significantly mediate effects, suggesting that short-term PM pollution affects cognitive function through lung-brain mechanisms, either directly or indirectly. It is unknown if the inhalation route (nasal or oral) of particulate matter (PM) air pollution affects cognition. Here the authors show PM exposure impaired selective attention and emotion recognition but not working memory or vigilance, with no mediation by inhalation.

Transfer of learning refers to successful application of previously acquired knowledge or skills to novel settings. Although working memory (WM) is thought to play a role in transfer learning, direct evidence of the effect of limitations in WM on transfer learning is lacking. To investigate, we used an acquired equivalence paradigm that included tests of association and transfer learning. The effects of imposing an acute WM limitation on young adults was tested (within-subjects design: N = 27 adults; M age = 24 years) by conducting learning transfer tests concurrent with a secondary task that required carrying a spatial WM load when performing the learned/transfer trial (Load condition) to acutely limit WM resources or no WM load (No-Load condition; WM was unloaded prior to performing the learned/transfer trial). Analyses showed that although success on the transfer trials was high in the No-Load condition, performance dropped to chance in the Load condition. Performance on tests of learned associations remained high in both conditions. These results indicate that transfer of learning depends on access to WM resources and suggest that even healthy young individuals may be affected in their ability to cross-utilize knowledge when cognitive resources become scarce, such as when engaging in two tasks simultaneously (e.g., using satellite navigation while driving).

Authenticating valuable objects is widely assumed to involve protracted scrutiny for detection of reproduction flaws. Yet, accurate authentication of banknotes is possible within one second of viewing, suggesting that rapid neural processes may underpin counterfeit detection. To investigate, we measured event-related brain potentials (ERPs) in response to briefly viewed genuine or forensically recovered counterfeit banknotes presented in a visual oddball counterfeit detection task. Three ERP components, P1, P3, and extended P3, were assessed for each combination of banknote type (genuine, counterfeit) and overt response (“real”, “fake”). P1 amplitude was greater for oddballs, demonstrating that the initial feedforward sweep of visual processing yields the essential information for differentiating genuine from counterfeit. A similar oddball effect was found for P3. The magnitude of this P3 effect was positively correlated with behavioural counterfeit sensitivity, although the corresponding correlation for P1 was not. For the extended P3, amplitude was greatest for correctly detected counterfeits and similarly small for missed counterfeits, incorrectly and correctly categorised genuine banknotes. These results show that authentication of complex stimuli involves a cascade of neural processes that unfolds in under a second, beginning with a very rapid sensory analysis, followed by a later decision stage requiring higher level processing.

Experimental studies show that inflammation impairs the ability to interpret the mental state of another person, denoted theory of mind (ToM). The current study attempted a conceptual replication in states associated with elevated low-grade inflammation, i.e., high body weight and advanced age. Ninety young (M = 26.3 years, SD = 4.1) or older (M = 70.7 years, SD = 4.0) participants with either a normal body mass index (BMI) (M = 22.4, SD = 2.2) or high BMI (M = 33.1, SD = 3.8) completed the Reading the Mind in the Eyes Test (RMET) to assess emotion recognition. Plasma interleukin-6 (IL-6) level was measured to index low-grade inflammation. As anticipated, elevated IL-6 levels were found with higher BMI, although not with increased age. IL-6 was associated with poorer task performance, independent of potential demographic and health confounders (e.g., sex, education, smoking status, alcohol intake, presence of medical conditions, and medication intake). Analyses also revealed an interaction whereby young individuals with a high BMI showed worse RMET performance compared to their normal BMI counterparts, whereas the opposite pattern was found in older individuals. The present observational study replicated experimental results showing that elevated low-grade inflammation is correlated with a lower ability to infer the mental states of others. These findings suggest that also naturalistic conditions of (protracted) low-grade inflammation may alter emotion recognition.

Urban residents are frequently exposed to high levels of traffic-derived air pollution for short time periods, often (but not exclusively) during commuting. Although chronic air pollution exposure and health effects, including neurological effects on children and older adults, are known to be correlated, causal effects of acute pollution exposure on brain function in healthy young adults remain sparsely investigated. Neuroinflammatory accounts suggest effects could be delayed by several hours and could affect attention, especially in social contexts. Using a controlled atmosphere chamber, we exposed 81 healthy young adults to either diluted diesel exhaust (equivalent to polluted roadside environments) or clean air for one hour. Half of each group immediately completed a selective attention task to assess cognitive control; remaining participants completed the task after a 4-hour delay. Cognitive control was significantly poorer after diesel versus clean air exposure for those in the delay but not immediate test condition, suggesting an inflammatory basis for this acute negative effect of air pollution on cognition. These findings provide the first experimental evidence that acute diesel exposure, comparable to polluted city streets, causes a negative effect on cognitive control several hours later. These findings may explain commuter mental fatigue and support clean-air initiatives.

Research suggests that human brain health is harmed by chronic exposure to neurotoxic atmospheric pollutants, probably as a result of neuroinflammatory responses. Previous studies correlated chronic air pollution exposure to children’s neurodevelopment and to neurodegeneration in the elderly, without using explicit, focussed cognitive tasks. Although vaccination studies show that acute inflammation can impact attention and social cognition a few hours after vaccination, whether exposure to air pollution could cause similar cognitive dysfunction is unknown. Using an atmospheric chamber, we exposed 81 young healthy adults to diluted diesel exhaust (or clean air) for one hour before completing a facial identification task either immediately or after a four-hour delay period. In the face task, participants made speeded identifications of the gender of a briefly presented target face in the presence of simultaneously presented distractor face (2-face trials) or a scrambled image distractor (1-face trial). Response times (RT) for 2-face trials preceded by a 2-face trial (repeat sequences) versus a 1-face trial (non-repeat sequence) were compared to index reactive attention. Poor control over reactive attention is associated with large differences is such tasks. A significant interaction between sequence type and pollution group was identified, such that reactive attention (non-repeat minus repeated sequences) was 22ms greater for the delayed-diesel compared to the delayed-clean air group, indicating that the former had less efficient adaptive cognitive control. Reactive attention was unaffected by diesel exposure when tested immediately after exposure; response accuracy was similar for all groups arguing against the possibility that speed-accuracy trade-offs could explain the results. These findings provide the first direct experimental evidence that short, city street comparable (8.89μg/m3 PM2.5; 206ppb NO2) diesel exposure can negatively impact attentional executive functioning several hours later. Finding delayed rather than immediate effects support the possibility that such effects stem from neuroimmune, rather than respiratory, responses.

This research was supported by a studentship from The Leverhulme Trust (Forest Edge Project).

How does the brain combine information predictive of the value of a visually guided task (incentive value) with information predictive of where task-relevant stimuli may occur (spatial certainty)? Human behavioural evidence indicates that these two predictions may be combined additively to bias visual selection ( Additive Hypothesis ), whereas neuroeconomic studies posit that they may be multiplicatively combined ( Expected Value Hypothesis ). We sought to adjudicate between these two alternatives. Participants viewed two coloured placeholders that specified the potential value of correctly identifying an imminent letter target if it appeared in that placeholder. Then, prior to the target’s presentation, an endogenous spatial cue was presented indicating the target’s more likely location. Spatial cues were parametrically manipulated with regard to the information gained (in bits). Across two experiments, performance was better for targets appearing in high versus low value placeholders and better when targets appeared in validly cued locations. Interestingly, as shown with a Bayesian model selection approach, these effects did not interact, clearly supporting the Additive Hypothesis. Even when conditions were adjusted to increase the optimality of a multiplicative operation, support for it remained. These findings refute recent theories that expected value computations are the singular mechanism driving the deployment of endogenous spatial attention. Instead, incentive value and spatial certainty seem to act independently to influence visual selection.

This research was supported by a studentship from The Leverhulme Trust (Forest Edge Project).

Obesity may accelerate cognitive aging and inflammation has been proposed as underlying mechanism. Using a 4-group design, the present study investigated associations of obesity and aging in relation to psychomotor speed and attentional processes using the Attention Network Test. Further, we tested to what extent these associations, if any, were mediated by inflammation. Ninety participants (61% male) were enrolled; 41 were classified as lean (mean BMI = 22.4) and 48 as obese (mean BMI = 33.1). Divided evenly over these weight-groups, 42 participants were young (mean age = 26; 21–35) and 48 were older adults (mean age = 71; 63–80). Blood was collected to assess the inflammatory marker IL-6. Both increasing age and obesity were independently associated with psychomotor speed (r=.688 and r=.318, respectively; p<.001), as well as with higher inflammation (r=.266 and r=.638, respectively; p<.05). Psychomotor slowing was also linked to elevated IL-6 (r=-.429, p<.001). Inflammation fully mediated the association of obesity with psychomotor slowing, and partially accounted for age-related psychomotor slowing. After adjustment for psychomotor speed, the data provided no evidence for obesity- or inflammation-associated attention impairments. The present observations showed slower task-responses in obese individuals, consistent with an aging-like effect. Moreover, shown for the first time, inflammation mediated obesity- and age-related psychomotor slowing. Currently follow-up studies are testing other aging-like effects on cognition associated with obesity and the mediating role of inflammation.

The ability to interpret someone’s mental state such as their emotions and intentions (denoted Theory of Mind, ToM), is key to human social interaction. This ability is impaired in several psychopathologies including major depression, and inflammation has been proposed as a candidate mechanism of such impairments. Experimental studies using LPS injection support a role of inflammation, but LPS-induced symptoms of sickness could themselves cause the observed reductions in ToM behaviors. Here we experimentally replicated these effects using a manipulation that minimized these potentially confounding side-effects. Forty healthy male participants (mean age = 25, SD= 5) completed the Reading the Mind in the Eyes Test (a measure of ToM) in this double-blind placebo-controlled within-subjects crossover triaI. Inflammation was induced using Salmonella Typhi vaccination (0.025 mg; Typhim Vi, Sanofi Pasteur) and saline-injection was used as a control. IL-6 was used as a marker of inflammation. Vaccination increased IL-6 levels (+419%, p<.001), without inducing fever or sickness symptoms (e.g., nausea), or mood changes (all p > .10). The results showed that typhoid vaccination significantly reduced ToM performance compared to placebo (M = 71%, SD = 13%’ placebo M = 65%, SD = 13%; p<.05). The present findings provide further support for the idea that emotion recognition is impaired during immune activation. Inflammation may in part drive social-cognitive deficits in pathologies that exhibit enhanced inflammation, such as major depression.

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Inflammation (immune system activation) affects neuronal function and may have consequences for the efficiency and speed of functional brain processes. Indeed, unusually slow psychomotor speed, a measure predictive of behavioural performance and health outcomes, is found with obesity and ageing, two conditions also associated with chronic inflammation. Yet whether inflammation is the mediating factor remains unclear. Here, we assessed inflammation by indexing interleukin-6 level in blood and measured psychomotor speed as well as indices of selective visual attention in young (mean = 26 years) or old (mean = 71 years) adults ( N = 83) who were either lean or currently significantly overweight (mean body mass index = 22.4 and 33.8, respectively). Inflammation was positively and significantly correlated with psychomotor speed, age, and body mass index but not with attention measures. Using mediation analyses we show for the first time that inflammation fully accounts for the significant psychomotor slowing found in those with high BMI. Moreover, we further show that age-related psychomotor slowing is partially mediated by inflammation. These findings support the proposal that reducing inflammation may mitigate weight- and age-related cognitive decline and thereby improve performance on daily tasks and health outcomes more generally.

Fatigue and dysphoria are highly prevalent in patients with chronic medical diseases, characterized by impairments in motivated behavior. Inflammation has been proposed as a biological mechanism, but supporting evidence has mostly been accrued through animal studies and correlational human data, while experimental human studies have remained sparse. Hence, the current study tested the effects of induced inflammation on motivated and goal-directed behavior in humans. This double-blinded placebo-controlled within-subjects study (N = 40 healthy males, mean age = 25 SD = 5) used salmonella typhoid vaccination (0.025 mg; Typhim Vi, Sanofi Pasteur) to induce acute inflammation; saline was used as placebo-control. Participants completed a reward-learning task that assessed distinguishable aspects of motivational learning. These are contingency learning, i.e., association of Abstract symbols with monetary rewards/punishments; maintenance of reward-based responses, and goal-directed adaptation to an unannounced change in reward-contingencies. Vaccination increased IL-6 levels (vaccination + 419%; placebo −10%; p<.001), confirming presence of inflammation. While in both vaccine and placebo conditions participants reached the same optimum performance level, vaccinated participants required more trials to reach this optimal level, indicating slower reward-based learning. Moreover, in the inflammation condition participants were less able to maintain optimal performance over successive trials and showed less goal-directed behavior, p’s<.05. The current results provide the first human evidence that inflammation impaired motivated learning, specifically reducing stability and maintenance of motivated behaviors, and goal-directed behavior.

Objectives Get Healthy in Pregnancy (GHiP) is a telephone based lifestyle coaching service for pregnant women, in New South Wales, Australia. GHiP had two service options; a telephone-based health coaching program consisting of up to 10 calls and information only (including one call). This study sought to compare the outcomes of the two GHiP options, to determine the characteristics of women likely to use the service and to explore the feedback from women and health professionals. Methods A pragmatic stratified clustered randomised controlled trial was conducted. Two metro and three rural hospitals were randomised into health coaching or information only arms. Self-reported measures of height and weight and health behaviours (dietary and physical activity) were collected at baseline and 36 weeks gestation. Process evaluation included descriptive analysis of routine program data, and semi-structured interviews with participants and health professionals. Results Of 3736 women screened, 1589 (42.5%) were eligible to participate, and of those eligible, 923 (58.1%) were recruited. More women in the health coaching arm gained weight within the target range for their BMI at 36 weeks gestation (42.9%) compared with information only (31.9%). Women found GHiP to be useful and supportive and midwives and doctors said that it facilitated conversations about weight with pregnant women. Conclusions for Practice Telephone-based lifestyle programs integrated with routine clinical care show promise in helping pregnant women achieve healthy gestational weight gain, but in this case was not significantly different from one information telephone call. Strong positive feedback suggests that scaled-up service delivery would be well received. TRIAL REGISTRATION: ACTRN12615000397516 (retrospectively registered).

Authentication is an important cognitive process used to determine whether one's initial identification of an object is corroborated by additional sensory information. Although authentication is critical for safe interaction with many objects, including food, websites, and valuable documents, the visual orienting strategies used to garner additional sensory data to support authentication remain poorly understood. When reliable visual cues to counterfeit cannot be anticipated, distributing fixations widely across an object's surface might be useful. However, strategic fixation of specific object-defining attributes would be more efficient and should lead to better authentication performance. To investigate, we monitored eye movements during a repetitive banknote authentication task involving genuine and counterfeit banknotes. Although fixations were distributed widely across the note prior to authentication decisions, preference for hard-to mimic areas and avoidance of easily mimicked areas was evident. However, there was a strong tendency to initially fixate the banknote's portrait, and only thereafter did eye movement control appear to be more strategic. Those who directed a greater proportion of fixations at hard-to-mimic areas and resisted more easily mimicked areas performed better on the authenticity task. The tendency to deploy strategic fixation improved with experience, suggesting that authentication benefits from precise visual orienting and refined categorisation criteria.

ABSTRACT Illness is often accompanied by perceived cognitive sluggishness, a symptom that may stem from immune system activation. The current study used electroencephalography (EEG) to assess how inflammation affected three different distinct attentional processes: alerting, orienting and executive control. In a double-blinded placebo-controlled within-subjects design (20 healthy males, mean age = 24.5, SD = 3.4), Salmonella typhoid vaccination (0.025 mg; Typhim Vi, SanofiPasteur) was used to induce transient mild inflammation, while a saline injection served as a placebo-control. Participants completed the Attention Network Test with concurrent EEG recorded six hours post-injection. Analyses focused on behavioral task performance and on modulation of oscillatory EEG activity in the alpha band (9-12 Hz) for alerting as well as orienting attention and frontal theta band (4-8 Hz) for executive control. Vaccination induced mild systemic inflammation, as assessed by interleukin-6 (IL-6) levels. While no behavioral task performance differences between the inflammation and placebo condition were evident, inflammation caused significant alterations to task-related brain activity. Specifically, inflammation produced greater cue-induced suppression of alpha power in the alerting aspect of attention while individual variation in the inflammatory response was significantly correlated with the degree of alpha power suppression. Notably, inflammation did not affect orienting (i.e., alpha lateralization) or executive control (i.e., frontal theta activity). These results reveal a unique neurophysiological vulnerability to acute mild inflammation of the neural network that underpins attentional alerting functions. Observed in the absence of performance decrements, these novel findings suggest that acute inflammation requires individuals to exert greater cognitive effort when preparing for a task in order to maintain adequate behavioral performance. Highlights Typhoid vaccination induced a transient mild inflammatory state Mild inflammation alters neurophysiological process associated with attention Mild inflammation selectively increased alerting-related alpha suppression while behavior was unaffected A greater inflammatory response was correlated with more alpha suppression

The combustion characteristics and thermal performance of a premixed H2/air combustion in the micro-combustor with a backward-facing step is studied through experimental tests and numerical simulations. The effects of step length and wall thickness on the flame stability and thermal performance of the micro-combustor are presented and compared. The results show that the outer wall temperature can be improved by the reduction of wall thickness and modified through the relocation of the high temperature zone. With the decrease of the step length, the flame location is reduced in the combustion chamber, while the same location of peak temperature is obtained in the combustors with varied wall thicknesses. The efficiency of the micro thermophotovoltaic (micro-TPV) system with GaSb and InGaAsSb PV cells are calculated and compared. The micro-TPV system with GaInAsSb PV cells and the micro-combustor with step length 5 mm and outer diameter 3.6 mm produced the highest energy output and efficiency.

Illness is often accompanied by perceived cognitive sluggishness, a symptom that may stem from immune system activation. The current study used electroencephalography (EEG) to assess how inflammation affected three different distinct attentional processes: alerting, orienting and executive control. In a double-blinded placebo-controlled within-subjects design (20 healthy males, mean age = 24.5, SD = 3.4), Salmonella typhoid vaccination (0.025 mg; Typhim Vi, Sanofi Pasteur) was used to induce transient mild inflammation, while a saline injection served as a placebo-control. Participants completed the Attention Network Test with concurrent EEG recorded 6 h post-injection. Analyses focused on behavioral task performance and on modulation of oscillatory EEG activity in the alpha band (9-12 Hz) for alerting as well as orienting attention and frontal theta band (4-8 Hz) for executive control. Vaccination induced mild systemic inflammation, as assessed by interleukin-6 (IL-6) levels. While no behavioral task performance differences between the inflammation and placebo condition were evident, inflammation caused significant alterations to task-related brain activity. Specifically, inflammation produced greater cue-induced suppression of alpha power in the alerting aspect of attention and individual variation in the inflammatory response was significantly correlated with the degree of alpha power suppression. Notably, inflammation did not affect orienting (i.e., alpha lateralization) or executive control (i.e., frontal theta activity). These results reveal a unique neurophysiological sensitivity to acute mild inflammation of the neural network that underpins attentional alerting functions. Observed in the absence of performance decrements, these novel findings suggest that acute inflammation requires individuals to exert greater cognitive effort when preparing for a task in order to maintain adequate behavioral performance.

There is an established link between social isolation and poor health outcomes, although the exact mechanisms explaining this association remain unclear. Lonely individuals show an enhanced inflammatory response to acute stress, and in the present study we investigated if loneliness also predicts inflammatory responses to a standardized immune challenge (typhoid vaccination). Using a within-subjects crossover design (double-blind, placebo-controlled), 40 healthy male participants (mean age = 25, SD = 5) received a Salmonella Typhi vaccination (0.025 mg; Typhim Vi, Sanofi Pasteur, UK) or Placebo (saline) on two separate occasions, at least 1 week apart. Loneliness was assessed using the UCLA-R loneliness scale. As expected, vaccination increased IL-6 levels (vaccination + 419%; placebo −10%; p < .001). This response was not accompanied by fever, sickness symptoms (e.g., nausea), or mood changes (all p > .10). Regression analyses showed that those scoring higher on loneliness showed a stronger IL-6 response (beta = 0.416, p < .05; using placebo as a reference). This association withstood adjustment for a range of potentially confounding variables, including health behaviors (e.g., exercise, alcohol) and depressive symptoms. Enhanced inflammatory reactivity in more lonely individuals may form a pathway linking perceived social isolation to poorer health outcomes.