Introduction: Gamma-band oscillations (30-200 Hz) support cognitive functions such as memory, perception, and decision-making, which are often impaired in neuropsychiatric disorders including schizophrenia, Alzheimer's disease, and Parkinson's disease. These disorders show distinct gamma abnormalities that are promising targets for transcranial alternating current stimulation (tACS). However, phase-specific adaptation of stimulation to ongoing gamma activity has long been considered unfeasible due to the low signal-to-noise ratio (SNR) of non-invasive recordings and stimulation-related artifacts. Recent advances in quantum sensing now offer improved SNR, enabling phase-locked modulation of gamma oscillations. Methods: We tested whether gamma-frequency brain oscillations can be assessed at the single-trial level and modulated by amplitude-modulated tACS (AM-tACS) in a phase-specific manner. Using 16 optically pumped magnetometers (OPMs), we recorded 40 Hz auditory steady-state responses (ASSRs) in 19 participants during AM-tACS applied over the temporal lobe at randomly assigned phase lags relative to the ASSR. Participants judged the loudness of auditory stimuli, while occipital stimulation served as a control condition. We hypothesized that AM-tACS would alter ASSR latency, a measure of cortical synchronization, and loudness perception only when targeting the temporal lobe. Results and conclusion: AM-tACS modulated both ASSR latency (p < 0.05) and loudness perception (p < 0.05) in a phase-dependent manner during temporal but not occipital stimulation. Physiological and behavioral effects were correlated across participants in modulation strength (r = 0.613, p < 0.01), while an exploratory post-hoc analysis suggested that they are also linked in modulation phase (V = 5.38, p < 0.05). These findings establish the feasibility of single-trial assessment and phase-specific modulation of gamma oscillations, advancing adaptive closed-loop tACS approaches for neuropsychiatric disorders.

Change blindness involves a failure to detect changes in a visual scene, despite the differences being available to visual perception. Although change detection is crucial for many every day or professional behaviours (e.g., driving, occupations such as radiology), little is known about the individual differences that contribute to change detection ability or the cognitive domains involved. Previous research has implicated attentional and visual memory processes in successful change detection. The present study used a naturalistic change detection task, the Alternate Forms Flicker Task (AFFT), paired with a battery of nine cognitive tests, to ascertain which cognitive domains are most strongly associated with change detection accuracy in a sample of 260 participants. Strongest correlates with AFFT accuracy were tasks assessing top-down attentional search (Visual Attentional Capture and Control Task), visuospatial ability and memory (Austin Maze and Object 2back Task), and visual inspection time (Subtle Cognitive Impairment Test). Principal Axis Factoring extraction with Promax rotation showed that cognitive flexibility, visuospatial working memory, and attention and processing speed collectively accounted for 41% of the variability in test battery scores. Using these three factors, a multiple linear regression model significantly accounted for 10.0% of the variability in AFFT scores. Visuospatial working memory was the principal factor, indicating that individual differences in visuospatial working memory likely contribute to differences in change detection accuracy.

Spin-Exchange Relaxation-Free Optically Pumped Magnetometers (SERF-OPMs) are increasingly used in multichannel biomagnetic sensing, yet their timing performance remains poorly characterized. This contribution presents the first cross-platform study of time delay, group delay, intra-channel variability, and settling time across four commercial SERF-OPM systems: Neuro-1 and QZFM Gen.2 (QuSpin Inc.), and HEDscan and FLv2 (FieldLine Inc.). Measurements were performed inside a magnetically shielded room (BMSR-2.1, PTB, Berlin) using an already introduced test bench. Results show frequency-dependent delays of 1-10 ms, intra-channel spreads up to +-1 ms, group delays between 1-15 ms, and settling times of 2-55 ms. Clear differences in manufacturer strategies were observed: QuSpin minimizes intra-channel variability through digital delay equalization, whereas FieldLine employs per-sensor calibration to optimize bandwidth and phase matching. In all systems, the time delay deviation between channels is in the sub-millisecond range in the 20-140 Hz band, which is sufficient for magnetoencephalography source localization. However, longer settling times in some platforms limit performance for rapid stimulation protocols. These findings provide the first vendor-comprehensive benchmarks for timing parameters in commercial SERF-OPM systems. They highlight the trade-offs between bandwidth, delay, and calibration strategies, and underscore the need for rigorous timing characterization to ensure waveform fidelity. The results are directly relevant to applications such as stimulation-evoked responses, brain-computer interfaces, and closed-loop neuromodulation.

Ischemia is a primary cause of microvascular disease, particularly in the hippocampus, which is unusually vulnerable to hypoperfusion and hypoxia. Since intermittent hypoxia is a defining feature of obstructive sleep apnoea (OSA), the present study examined microvessels in autopsy tissue from patients with clinically confirmed OSA. Immunohistochemistry was performed on 30 hippocampal autopsy samples to investigate whether the incidence of microvascular abnormalities is associated with increased OSA severity, and if so, whether regular use of continuous positive airway pressure (CPAP) is protective. There were significantly more string vessels (4.3 ± 0.9 vs. 1.7 ± 0.4, p = 0.014), narrowing vessels (3.5 ± 1.0 vs. 0.9 ± 0.3, p = 0.024), strictures (2.6 ± 0.4 vs. 1.1 ± 0.2, p = 0.002) and total abnormalities (10.3 ± 1.5 vs. 3.7 ± 0.6, p = 0.001) in the CA1 subregion of the moderate–severe OSA group (mean ODI 35.9 ± 6.4 events/h sleep) than in the mild–moderate OSA group (mean ODI 18.5 ± 3.7 events/h sleep). There were no significant differences between regular CPAP users and non-CPAP users, or between younger and older individuals. We conclude that in moderate–severe OSA, the preponderance of microvascular abnormalities in the CA1, which are too narrow to carry blood, amplify its vulnerability to ischemia.

Evidence has grown that the core pathology of age-related dementias, including Alzheimer's disease, is microvascular—small, symptomless bleeds from cerebral capillaries, accelerated by the hypertension of age. Each such bleed, this evidence suggests, damages a patch of brain, causing the death of neurons. This review asks how this vulnerability of the brain emerged from evolution, to cause age-related dementia? And has the vulnerability spurred the evolution of mitigating mechanisms? It is argued that seven features of human evolution contribute to the cause of dementia: the dependence of our tissues, especially the brain, on oxygen; the toxicity of the molecule (heme) that binds to oxygen to enable its transport; the pulsatility of the heart; the danger of glutamate as an excitatory neurotransmitter; the irreparability of elastin; the low level of adult neurogenesis in humans; and the breakdown, in late life, of the blood-brain barrier. Also discussed are mechanisms that have evolved to counter these threats to the brain, including the generation of a reserve of brain tissue. We argue that the vulnerabilities of the brain to damage that accumulates throughout life, and leads to dementia in the aged, were established early in the evolution of vertebrates. Several can be understood as unavoidable yet damaging outcomes of highly advantageous steps in evolution. Human cognition fails when and because, with age, the damage that results from these vulnerabilities overwhelms the evolved protections and exhausts any reserve of brain tissue. Implications of these vulnerabilities for the delay and management of dementia are discussed.

INTRODUCTION:Drowsiness is a significant cause of crashes in the various transport industries, including automotive, aviation, and rail. Our previous study investigated the differential induction of drowsiness in drivers caused by specific whole-body vibration (WBV) frequency ranges, with an amplitude of 0.2 m/s2 r.m.s. The present companion study investigates the effects of different vibration amplitudes on the induction of driver drowsiness. METHOD:This study includes two experiments. In the first, 15 participants engaged in six 1-hour sessions of simulated driving, experiencing WBV at frequencies of 0 Hz (no vibration), 1-4 Hz, 4-8 Hz, 8-16 Hz, 16-32 Hz, or 32-64 Hz, with an amplitude of 0.1 m/s2 r.m.s. In the second experiment, another group of 15 participants underwent three 1-hour sessions of simulated driving, exposed to WBV at frequencies of 0 Hz, 1-4 Hz, and 4-8 Hz, with an amplitude of 0.05 m/s2 r.m.s. RESULTS:As indicated by driving performance, reaction time evaluations, and subjective reports, the extent of drowsiness decreased with decreasing vibration amplitude. PRACTICAL APPLICATIONS:Based on the results of this and our previous paper, discrete contours for WBV-induced drowsiness were developed. These contours will assist the transport industry in reducing the incidence of vehicle crashes caused by drowsiness.

Humans can remember a vast amount of scene images; an ability often attributed to encoding only low-fidelity gist traces of a scene. Instead, studies show a surprising amount of detail is retained for each scene image allowing them to be distinguished from highly similar in-category distractors. The gist trace for images can be relatively easily captured through both computational and behavioural techniques, but capturing detail is much harder. While detail can be broadly estimated at the categorical level (e.g. man-made scenes more complex than natural), there is a lack of both ground-truth detail data at the sample level and a way to operationalise it for measurement purposes. Here through three different studies, we investigate whether the perceptual complexity of scenes can serve as a suitable analogue for the detail present in a scene, and hence whether we can use complexity to determine the relationship between scene detail and visual long term memory for scenes. First we examine this relationship directly using the VISCHEMA datasets, to determine whether the perceived complexity of a scene interacts with memorability, finding a significant positive correlation between complexity and memory, in contrast to the hypothesised U-shaped relation often proposed in the literature. In the second study we model complexity via artificial means, and find that even predicted measures of complexity still correlate with the overall ground-truth memorability of a scene, indicating that complexity and memorability cannot be easily disentangled. Finally, we investigate how cognitive load impacts the influence of scene complexity on image memorability. Together, findings indicate complexity and memorability do vary non-linearly, but generally it is limited to the extremes of the image complexity ranges. The effect of complexity on memory closely mirrors previous findings that detail enhances memory, and suggests that complexity is a suitable analogue for detail in visual long-term scene memory.

Ultralow magnetic field sensing is rapidly emerging as a technology in various applications, providing a noninvasive and instantaneous method of data acquisition (DAQ). The increasing availability of improved or innovative types of magnetometers promotes the need for a benchmark metric. This contribution focuses on the evaluation of single magnetometer devices that detect magnetic fields in the femtotesla range and are usually used in a magnetically shielded environment. For assessment, a device alignment actuator system is presented that enables an accurate 3-D alignment of the device under test (DuT) around a single point within a known, homogeneous magnetic test field inside the highly magnetically shielded room (MSR), called BMSR-2.1 at the Physikalisch-Technische Bundesanstalt (PTB), Berlin, Germany. The defined benchmark metric includes several key parameters, such as frequency response, amplitude stability, frequency stability, and directivity, to name just a few. These parameters are introduced by using different commercial state-of-the-art spin exchange relaxation-free optically pumped magnetometers (SERF-OPMs) and compared to the reference system based on superconducting quantum interference devices (SQUIDs), which remain the gold standard in magnetometry. This approach ensures consistent evaluation across different magnetometer types, provided that they operate at room temperature and fit within the evaluation platform. The platform can also be adapted for multichannel magnetometer systems.

OBJECTIVES:To determine whether the regular consumption of milk free from A1 β-casein (A1PF milk) improves cognitive performance to a greater extent than conventional milk, and if so, whether such improvements are associated with an increase in the serum titres of reduced glutathione (GSH). DESIGN:A multi-centre, double-blind, randomised controlled trial with two parallel arms, conducted from 7 March 2023 to 13 October 2023. SETTING:Two hospitals in Tianjin, China. PARTICIPANTS:Volunteers (N = 96) diagnosed with mild cognitive impairment (MCI) and aged between 65 and 75 years. INTERVENTION:A1PF skim milk powder or conventional skim milk powder, diluted into liquid form (200 mL) and consumed twice daily for 90 days. MEASUREMENTS:The primary outcomes were cognitive performance (assessed with the Subtle Cognitive Impairment Test [SCIT]) and serum titres of GSH. Secondary outcomes included performance on two other cognitive tests, serum levels of 25-hydroxyvitamin D3, subjective quality of life (QoL), muscle strength (hand grip scale), faecal and blood inflammatory markers. RESULTS:Data from 91 participants were analysed (A1PF milk group: n = 45; conventional milk group: n = 46). A1PF milk improved performance on all three cognitive tests to a greater extent than conventional milk; however, this improvement was not associated with an increase in serum GSH. When compared with conventional milk, A1PF milk resulted in higher increases in serum levels of 25-hydroxyvitamin D3, greater subjective improvements in QoL and improved left hand grip strength. There were no between-group differences in inflammatory markers, calcium absorption or bone density markers. CONCLUSION:Daily intake of A1PF milk for 90 days significantly improved cognition, QoL and muscle strength in a sample of older people with MCI. While these outcomes appear to be linked to increased serum titres of 25-hydroxyvitamin D3, further investigations are needed to confirm this association. CLINICAL TRIAL REGISTRATION:NCT05741047 (clinicaltrials.gov).

This review explores the hypothesis that dementia in several forms, chronic kidney disease and idiopathic pulmonary fibrosis have a common cause in pulse-induced capillary haemorrhage. All three conditions are age-related and characterised by insidious onset, uncertainty about their cause, exacerbation by hypertension, resistance to treatment and the relentlessness of their progression. We argue that the three conditions are the clinical outcomes of damage caused by pulse-induced haemorrhage from capillaries. The damage, first detectable in mid-life, creates first mild and then severe symptoms of cognitive, renal and pulmonary dysfunction. We also review evidence that in all three organs there has developed, by young adulthood, a reserve of tissue that enables them to function well, despite the ‘heartbeat by heartbeat’ damage that accumulates from early mid-life; and that it is when that reserve is exhausted, typically in late age, that symptoms of organ failure emerge and progress. If this common cause can be established, a step will have been taken towards the understanding, treatment and delay of three conditions that have their beginnings in every individual and that, in those who survive other causes of death, become lethal in late age.

The gut and brain communicate through bidirectional neural, endocrine, and immune signals to coordinate central nervous system activity with gastrointestinal function. Dysregulated inflammation can promote immune cell activation and increase entero-endocrine signaling and intestinal permeability; hence, a functional gut-brain axis is necessary for a healthy digestive system. The consumption of milk products can lead to gut discomfort via effects on gastrointestinal tract function and the inflammatory state, which, in turn, affect the brain. A1 beta-casein and A2 beta-casein are major components of bovine-milk protein, and their digestion may result in different physiological effects following the consumption of milk products. Peptides derived from A1 beta-casein, such as beta-casomorphins, may increase gut dysfunction and inflammation, thereby modulating the availability of bioactive metabolites in the bloodstream and contribute to changes in cognitive function. This narrative review examines the functional interrelationships between the consumption of cow-milk-derived beta-caseins and their effect on the brain, immune system, and the gut, which together comprise the gut-brain axis.

This review advances an understanding of several dementias, based on four premises. One is that capillary hemorrhage is prominent in the pathogenesis of the dementias considered (dementia pugilistica, chronic traumatic encephalopathy, traumatic brain damage, Alzheimer's disease). The second premise is that hemorrhage introduces four neurotoxic factors into brain tissue: hypoxia of the tissue that has lost its blood supply, hemoglobin and its breakdown products, excitotoxic levels of glutamate, and opportunistic pathogens that can infect brain cells and induce a cytotoxic immune response. The third premise is that where organisms evolve molecules that are toxic to itself, like the neurotoxicity ascribed to hemoglobin, amyloid- (A), and glutamate, there must be some role for the molecule that gives the organism a selection advantage. The fourth is the known survival-advantage roles of hemoglobin (oxygen transport), of A (neurotrophic, synaptotrophic, detoxification of heme, protective against pathogens) and of glutamate (a major neurotransmitter). From these premises, we propose 1) that the brain has evolved a multi-factor response to intracerebral hemorrhage, which includes the expression of several protective molecules, including haptoglobin, hemopexin and A; and 2) that it is logical, given these premises, to posit that the four neurotoxic factors set out above, which are introduced into the brain by hemorrhage, drive the progression of the capillary-hemorrhage dementias. In this view, A expressed at the loci of neuronal death in these dementias functions not as a toxin but as a first responder, mitigating the toxicity of hemoglobin and the infection of the brain by opportunistic pathogens.

We propose that the human respiratory system and olfactory pathways sequester airborne nutrients (vitamins, fatty acids, and trace minerals) that are beneficial for health, which we term “aeronutrients.” In addition, airborne bacteria, termed “aeromicrobes,” have the potential for positive health effects by improving species diversity in the microbiotas of the respiratory and gastrointestinal tracts. These concepts have implications for people living in urban areas or those who have limited access to nature, such as astronauts exposed for long periods to highly filtered air that may be depleted of aeronutrients and aeromicrobes. The possibility that fresh air contributes to human nutrition and health may stimulate a re-evaluation of guidelines pertaining to nutrition and access to natural environments, and will open new avenues of scientific enquiry.

As the semi-automation of motor vehicles advances, the prevalence of multitasking and task switching while driving has increased. In the next phase, known as conditional automated driving (level 3 automation), drivers will be able to fully engage in distracting tasks, yet they must be prepared to promptly resume control of the vehicle and maintain safe driving if requested to by the vehicle. In such situations, the driver's ability to flawlessly switch between the distracting task and the driving task becomes vitally important. This narrative review discusses conditional automated driving within the framework of cognitive psychology concepts of attention and task switching. Delayed reaction time and deteriorated driving performance are attributed to cognitive overload and switch cost. Factors that contribute to driving switch cost are identified and categorized, and several road safety concerns are raised, including: i) switch cost may last for between 20 s to 5 min; ii) inexperienced drivers may be unable to adequately control the vehicle after resuming manual control; and iii) low- and high-intensity non-driving tasks have a greater impact on takeover performance. To minimise the risk to road safety, suggestions have been provided to vehicle manufacturers, road users and regulatory authorities.

Multi-limb coordination is necessary for many daily activities. It also has particular relevance for a growing area of human-system applications such as teleoperated robot operation and supernumerary robot operation where an additional robotic limb may complement natural limb functions. Introducing sup-plemental sensory information, specifically haptic feedback, has shown the potential to improve assistive robotics control, human-machine interactions, and even human motor learning. However, there has been little research on how sensory information, including haptic feedback and visual information, contributes to the execution of multi-limb coordinated tasks. In this paper, we designed a tri-limb coordinated task where participants move a cursor to a randomly positioned target on a screen guided by variations of both haptic feedback and visual information. Our results indicated that while haptic feedback could partially sub-stitute for visual information, it could not completely replace nor surpass the task performance achieved with visual information as feedback. Importantly, haptic feedback does not negatively impact performance metrics such as how often the participant coordinates multiple limbs simultaneously (coordination score), controls their limbs without redundant movement (normalized sub-optimal path), completes the task (success rate), and the mental workload perceived during the task (cognitive load). This study provides insight into the contribution of sensory feedback in facilitating multi-limb coordination, providing relevant guidance for numerous applications of human interactions with assistive technologies.

Since driving while drowsy is a significant cause of vehicle accidents, road safety could be improved if more effective methods were available for improving driver alertness. The present paper investigated whether it is possible to improve alertness via a wearable device that applied somatosensory vibration to the driver's wrist. The vibration used modulation frequencies ranging from 12 Hz to 50 Hz and a carrier frequency of 250 Hz. Random on-and-off intervals and variable vibration amplitudes were used to minimise sensory adaptation. Fifteen participants undertook a sixty-minute simulated driving task that caused drowsiness. Karolinska Sleepiness Scale (KSS), Power Spectral Density (PSD) and Higuchi's Fractal Dimension (HFD) analyses of brainwave signals were used to identify variations in driver alertness. The vibration stimulus was found to significantly improve alertness when compared to a no-vibration condition. Participants experienced an immediate improvement in alertness that reached significance within 9 minutes and was then sustained at the level seen at the beginning of the experiment, indicating a full restoration of alertness. This result demonstrates that wearable vibration devices have the potential to improve alertness in drivers.

Driver drowsiness is a factor in at least 20% of serious motor vehicle accidents. Although research has shown that Whole-Body Vibration (WBV) can induce drowsiness in drivers, it is unknown whether particular frequencies are more problematic. The present study systematically investigated the influence of WBV frequency on driver drowsiness. Fifteen participants each undertook six 1-h sessions of simulated driving while being subjected to WBV of either 0 Hz (no vibration), 1-4 Hz, 4-8 Hz, 8-16 Hz, 16-32 Hz or 32-64 Hz. Subjective sleepiness, as measured by the Karolinska Sleepiness Scale (KSS), confirmed that drivers felt drowsier when exposed to the two lowest frequency ranges (1-4 Hz and 4-8 Hz). Reaction time, which measures attention and alertness, was significantly impaired by the two lowest frequency ranges. Objective driving performance measures (Standard Deviation of Lane Position (SDLP), Standard Deviation of (SD) Steering Angle, Time in Unsafe Zone) also showed significant degradation due to exposure to the two lowest frequency ranges. Exposure to 1-4 Hz or 4-8 Hz vibration caused attention to become significantly impaired within 15-20 min and driving performance to be significantly impaired by 30-35 min. The other frequency ranges had little or no effect. These findings point to a need to develop equivalent vibration-induced drowsiness contours that can be adopted as transportation safety standards.

During spacecraft robotic arm operations, haptic feedback has the potential to display rich streams of relevant data to the user, such as trajectory information and velocity. One promising strategy to encode such information is through tactile stroke illusions, which create the sensation of vibration moving across the skin. This study highlights the design and feasibility testing of a haptic wearable in- terface worn on the user's forearm in a sleeve form factor that elicits tactile stroke illusions, using an array of vibration actuators in a timed sequence. By manipulating the temporal aspects and devel- oping two rendering algorithms to convey end-effector movement information, we demonstrate the feasibility of our haptic sleeve wearable by human testing to measure how accurately participants perceive the conveyed information (trajectory and velocity).

The elevated plus maze is intended to provoke anxiety-like behaviour, which is primarily measured by the degree to which the rodent explores or avoids the risker, unenclosed arms. Measures such as arm entries and total time spent within the arm are conventionally used, but their analysis often produces inconsistent inferences about the level of anxiety-like behaviour being observed. This inconsistency occurs because the measures do not correlate with one another, raising the question of how validly they capture both the exploratory and avoidance motivations that typify anxiety-like behaviour. Given this inconsistency, we propose a new measure, novel exploration growth, that captures avoidance and exploratory behaviours within the maze. The growth of novel exploration tracks the first visit to discrete areas of the maze over time. The absolute amount of novel exploration, combined with the phasic nature of the exploration, reveals behavioural phenotypes with both avoidance and exploration quantified in a single time series. By addressing both motivations evoked by the maze through a single coherent measure, we provide a superior estimation of anxiety-like behaviour and resolve inconsistencies that arise when applying conventional measures alone. ### Competing Interest Statement The authors have declared no competing interest.

Explainable AI (XAI) is a subfield of human-agent interaction that involves the design and development of methods that generate explanations and exhibit more transparent behavior from AI agents. In this work we present three contributions that advance XAI research in the context of Human-Robot Interaction (HRI). First, we extend explanation generation using behavior trees to include projection-level XAI, i.e. the ability to query an agent for explanations on future actions. Second, we developed algorithms that answer pre- and post-conditions of an action, which we hypothesize improves comprehension of an agent. Third, we present an experimental design using a robot arm and GUI to evaluate the efficacy of the explanation generation approach on various levels of user situational awareness, workload, and trust. All code is open-source to allow researchers to explore using explanation generation with behavior trees for future human-robot interaction studies.