Flexible prioritization in working memory (WM) is supported by neural oscillations in frontal and sensory brain areas, but the roles of different oscillations remain poorly understood. Recordings in humans suggest an interplay between prefrontal slow frequency (2-8 Hz) and posterior alpha-band (10 Hz) oscillations regulating top-down control and retrieval of WM representations, respectively. Complementary work, primarily in nonhuman primates, suggests an additional role for beta (15-30 Hz) oscillations in clearing or inhibiting stimuli from entering WM. Here we investigated the role of neural oscillations in prioritizing WM content using electroencephalography (EEG) as participants (humans of any sex) performed a task requiring frequent priority switches between two memorized oriented bars. Behavioral performance revealed switch costs, which scaled with the angular distance between the two items, suggesting that priority shifts are modulated by shift magnitude. Time-frequency analyses revealed increased frontal theta (4-8 Hz) and decreased central-parietal beta (15-25 Hz) power during switches. Crucially, only beta power scaled with the magnitude of the priority shift and predicted the fidelity of neural decoding of the newly prioritized item during subsequent recall. Theta power, in contrast, was elevated on switch trials but did not vary with update magnitude or decoding strength, suggesting a more general role in signaling control demands. Our findings highlight a particular and previously overlooked role for beta-band oscillations in the flexible prioritization of WM content.
The relationship between the geometry of neural representations and the task being performed is a central question in neuroscience. The primate prefrontal cortex (PFC) is a primary focus of inquiry, as it can encode information with geometries that either rely on past experience or are experience agnostic. One hypothesis is that PFC representations should evolve with learning, from a format that supports exploration of all possible task rules to a format that minimizes the encoding of task-irrelevant features and supports generalization. Here we test this idea by recording neural activity from the macaque PFC when learning a new rule ('XOR rule') from scratch. We show that PFC representations progress from being high dimensional, nonlinear and randomly mixed to low dimensional and rule selective. Upon generalizing the rule to new stimuli, these representations further evolve into an abstract, stimulus-invariant geometry. These findings reconcile previously conflicting accounts of PFC function by demonstrating how neural representations adapt across distinct stages of learning.
In this review and meta-analysis, we aimed to examine outcomes of interpersonal violence among autistic people. Intersectionality and minority theories suggest that negative outcomes are heightened among people with multiple marginalized identities. Thus, we also aimed to investigate gender-related outcomes of interpersonal violence among autistic people. We conducted a systematic database search with inclusion criteria including mixed methods, peer-reviewed research examining any harmful interpersonal act (e.g., physical, sexual, and psychological) experienced by autistic people. We undertook a random-effects meta-analysis with pooled data from 9 studies, comprising 3,647 autistic participants aged 1 to 80 years. Violence was associated with worsened mental health, with the strongest association for internalizing symptoms (d = 0.66, p < .001; 95% CI [0.51, 0.80]) and suicidal thoughts and behavior (d = 0.63, p < .001; [0.44, 0.82]). Narrative synthesis of 57 studies comprising 37,418 participants (13,127 autistic, 24,291 non-autistic) found violence was associated with numerous adverse health, development, and functional outcomes, including worsened mental health and behavioral difficulties compared to non-autistic controls from childhood. Females and gender minorities reported greater intra- and interpersonal health and development difficulties related to violence, emerging in early childhood and enduring into adulthood. Findings provide strong evidence of lifelong negative outcomes associated with interpersonal violence experienced by autistic people, providing evidence for the relevance of minority stress and intersectionality theories in understanding risk. Indeed, our results raise concerns that autistic people, and particularly non-male (female, gender diverse) individuals, have higher susceptibility for abuse from a young age, while being conditioned to respond with social desirability, superficial adaptivity, and dissociation.
Background:Autistic people are at significant risk for suicidal thoughts and behaviors (STBs) and nonsuicidal self-injury (NSSI). We examined STB and NSSI in different age-groups, considering sex- and age-based effects, in a pooled multinational sample of English-speaking autistic children and adults. Methods:We administered the Columbia-Suicide Severity Rating Scale to 245 autistic people without intellectual disability (139 youth and 106 adults; 46.1% female sex; M age = 24.8, SD age = 16.3 years, range = 7-70) or their caregivers in Australia, Canada, and the United States. The study samples were enriched with autistic people experiencing depression and suicidality. Results:Most participants (87.8%) reported suicidal ideation and NSSI (56.3%). Nearly one-third of autistic people (31.0%) reported a lifetime suicide attempt (M = 2.9 attempts; range = 1-26); overdosing was the most common method of suicide attempt. Sex was not a significant risk factor for suicidal ideation, behavior, or NSSI. Increases in lifetime suicidal ideation were observed across older age-groups, with those aged over 18 years reporting more severe and longer-lasting ideation than in children or adolescents. The youngest age of suicide attempt was 7 years in this sample, and the average ages of first/initial, most lethal, and most recent suicide attempts in youth (n = 24) and adults (n = 42) were 16.6, 19.2, and 20.8 years old, respectively. Conclusion:Regardless of age-group, autistic people across the lifespan constitute a high-priority group for suicide prevention strategies, development of appropriate assessments, and evaluation of system-level programs that effectively address the problem of preventable death by suicide.
AbstractWorking memory has been traditionally studied as a passive storage for information. However, recent advances have suggested that working memory is prospective rather than retrospective, meaning that its content undergoes transformations that will support future behaviour. One perspective that underscores this notion conceptualises memory processes as a computational resource that can be used to reduce the complexity of computation at decision time. Here, we explore this perspective by examining whether the process of maintenance shapes neural geometry and leads to low-dimensional representations during storage and later decision time. We recorded EEG in 25 human participants who learnt to solve a XOR task. We hypothesised that separating task features by a working memory delay would result in participants temporally decomposing the XOR computation, by prospectively processing one of the task features early in trial time. In line with our predictions, participants transformed the first feature from a sensory to an abstract format and maintained this pre-processed information throughout the delay. This process was related to the low-dimensional representation required at decision time early in learning, a representation that has recently been shown to support later cross-generalisation. These results demonstrate that low-dimensional representations, elsewhere associated with slow learning, might also provide a mechanism for maintenance processes in working memory.
Cognitive flexibility requires both the encoding of task-relevant and the ignoring of task-irrelevant stimuli. While the neural coding of task-relevant stimuli is increasingly well understood, the mechanisms for ignoring task-irrelevant stimuli remain poorly understood. Here, we study how task performance and biological constraints jointly determine the coding of relevant and irrelevant stimuli in neural circuits. Using mathematical analyses and task-optimized recurrent neural networks, we show that neural circuits can exhibit a range of representational geometries depending on the strength of neural noise and metabolic cost. By comparing these results with recordings from primate prefrontal cortex (PFC) over the course of learning, we show that neural activity in PFC changes in line with a minimal representational strategy. Specifically, our analyses reveal that the suppression of dynamically irrelevant stimuli is achieved by activity-silent, sub-threshold dynamics. Our results provide a normative explanation as to why PFC implements an adaptive, minimal representational strategy.
Frontopolar cortex (FPC) contains area 10, an anterior sub-region of prefrontal cortex exclusive to humans and nonhuman primates (NHPs) which is thought to support monitoring the value of switching between alternative goals. However, the neuronal mechanisms underlying this function are unclear. Here, we used multielectrode arrays to record the local field potentials (LFPs) in the FPC of two macaques performing a Wisconsin Card Sorting Test analogue and found that bursts of gamma and beta in FPC tracked counterfactual not current rule value. Moreover, we show that brief high-frequency microstimulation to a single trial causally affects both LFP activity in FPC, as well as rule-guided decision-making across successive trials. Following stimulation of FPC, we observed reduced exploration of the counterfactual rule prerule-change, as well as a delayed adaptation to the newly relevant rule postrule-change. A similar, multi-trial time-course disturbance to beta and gamma activity within FPC was also induced following single-trial microstimulation. These findings link neuronal activity in FPC with behavioral monitoring of the value of counterfactual rules and provide neural mechanistic insights into how FPC supports rule-based decision-making.
Cognitive flexibility is crucial for adaptive human behaviour. Prior studies have analysed the effect of reward on cognitive flexibility; however, the neural mechanisms underlying these effects remain largely unknown. This study explores how reward influences neural oscillations and how these changes impact behavioural performance. Using time-frequency decomposition, we examined electroencephalographic data from participants engaged in rule-guided task-switching with varying reward prospects. Higher anticipated rewards lead to greater desynchronisation of alpha (8-12 Hz) and beta (20-30 Hz) oscillations, which in turn correlated with improved task performance. Both alpha power and event-related potential (ERP) coding of reward independently predicted reward-based performance improvements, suggesting distinct mechanisms supporting proactive control. These findings underscore the unique contributions of neural oscillations in mediating motivational effects on cognitive flexibility.
Research has identified intersectional effects of autism and gender for experiences of interpersonal violence; however, findings have been mixed and vary by violence type. This systematic review and meta-analysis examined gender differences in autistic experiences of interpersonal violence prevalence. We identified 64 studies examining physical, sexual, or psychological violence, bullying, and homicide among autistic people, varying by gender, age, and support needs. We conducted a meta-analysis over 24 studies, and found increased violence experienced by autistic cis-females (d = 0.32) and gender minorities (d = 0.73) compared to cis-males. This review suggests autistic people experience disproportionate rates of violence compared to the general population, and highlights concerningly high rates of lifetime and poly-victimization, particularly among gender-marginalized groups.
Subjective wellbeing (SWB) represents an individual's perception of wellness that is supported by homeostatic mechanisms. These mechanisms are proposed to be maintained by low negative affect and high positive affect, although less is known about these mechanisms and SWB in autism. The current cross-sectional study aimed to compare patterns of positive affect, negative affect (Positive Affect and Negative Affect Scale), and SWB (Personal Wellbeing Index-School Children) between autistic (n = 53) and non-autistic (n = 49) individuals aged 10-22 years (Mage = 13.97, SD = 3.13). Between-group t-tests revealed that compared with same-age peers, autistic participants scored lower SWB overall (p < 0.001). In both groups average SWB scores fell into the higher range, however, autistic participants were three-times more likely to fall below this range when compared to non-autistic participants. Negative affect had a higher intercept in the autistic sample, but no difference in slopes were observed. A hierarchical multiple regression revealed that diagnosis, positive affect, and negative affect significantly predicted SWB in our sample. Between-group t-tests found no significant difference in positive affect or negative affect across age between the autistic and non-autistic samples. In autistic participants, positive affect increased across age as SWB decreased, whilst negative affect remained stable, a pattern inconsistent with homeostatic SWB. The current study is overall consistent with the homeostatic explanation for SWB within autism; however, we identified potential differences between autistic and non-autistic participants in the contribution of positive affect and negative affect to homeostatic protect mood across development.
In the dynamic environment we live in, the already limited information that human working memory can maintain needs to be constantly updated to optimally guide behaviour. Indeed, previous studies showed that leading up to a response, representations maintained in working memory representations are transformed continuously. This goes hand-in-hand with the removal of task-irrelevant items. However, does such removal also include the representations of stimuli as they were originally, prior to transformation? Here we assessed the neural representation of task-relevant transformed representations, and the no-longer-relevant veridical representations they originated from. We applied multivariate pattern analysis to electroencephalographic data during maintenance of orientation gratings with and without mental rotation. During maintenance, we perturbed the representational network by means of a visual impulse stimulus, and were thus able to successfully decode veridical as well as imaginary, transformed orientation gratings from impulse-driven activity. The impulse response reflected only task-relevant (cued), but not task-irrelevant (uncued) items, suggesting that the latter were quickly discarded from working memory. By contrast, even though the original cued orientation gratings were also no longer task-relevant after mental rotation, these items continued to be represented next to the rotated ones, in different representational formats. This seemingly inefficient use of scarce working memory capacity was associated with reduced probe response times and may thus serve to increase precision and flexibility in guiding behaviour in dynamic environments.
Background: Interpersonal violence is a widespread yet understudied issue in autism spectrum disorder (henceforth, 'autism'). Characteristic of autism are high rates of gender diversity, and so increased multiple minority group membership. Under minority stress and intersectionality models, minority identity presents greater risk of violence, while demographic variables (e.g., gender, sexuality, race) add to marginalisation and intersect to further enhance risk. However, research investigating risk and contextual predictors has been limited. This review examined individual, social, and life course risk factors associated with experiences of interpersonal violence among autistic people of varying gender identities. Methods: A systematic database search identified 59 studies examining violence: (1) combined physical, sexual, and/or psychological; (2) physical; (3) sexual; (4) psychological; (5) traditional bullying; (6) cyberbullying; and (7) homicide among autistic people of any age and support needs, varying by gender. Final included studies comprised 42,251 autistic (65.79% males, 32.91% females, 0.14% transgender, 0.69% non-binary/gender queer, 0.002% intersex, 0.46% gender n/s), and 269,433 non-autistic participants (32.57% males, 64.45% females, 0.006% non-binary/ gender queer, 2.98% gender n/s), aged 2-81 years. Results: Narrative synthesis of the 59 studies showed a consistent pattern of increased rates of overall and repeated violence across the life course among autistic compared to non-autistic people. Intersectional risk was identified across all socio-ecological levels: individual (e.g., autism-related factors, age, mental health, gender, demographic diversity); proximal social (e.g., parents, peers, partners), community (e.g., home, school, healthcare, police interaction), and broader social (e.g., safety education, violence prevention/support services, specialised care/training, public stigma). Conclusions: Our review indicates that interpersonal violence is a common issue for autistic people, who experience enhanced risk victimisation across the life course, particularly among multiply marginalised people (i.e., gender, race, sexuality, mental health). Our review underscores the importance of examining violence from an intersectionality and minority stress perspective and across socio-ecological contexts, and provides important empirical, legal, and policy implications.
Autistic adults experience high rates of unemployment, yet research investigating what predicts employment success produces inconsistent results. By utilising longitudinal person-oriented analyses, this study aimed to identify employment trajectories of autistic adults to better understand what may predict stable autistic employment. Participants were 2449 autistic adults (1077 men, 1352 women, 20 non-binary, M = 42.25 years, SD = 14.24), recruited via the Netherlands Autism Register. Latent class analysis utilising employment status across eight annual waves was used to identify longitudinal employment profiles. Fit indices and the interpretability of results indicated a four-class model best fit the data, with profiles reflecting stable unemployment (n = 1189), stable employment (n = 801), early unemployment increasing in probability of employment (n = 183) and high probability of employment reducing across time to low employment (n = 134). Multinominal analyses suggested that compared to the 'stable unemployment' group, membership in the 'stable employment' profile was predicted by fewer autistic traits, lower age, male gender, higher education and diagnosis age, and fewer co-occurring conditions. Higher education predicted both other profiles, with lower age and fewer co-occurring conditions predicting membership in the increasing employment class. Taken together, findings highlight the utility of person-oriented approaches in understanding the longitudinal challenges autistic adults experience maintaining employment and identifies key areas of support. Lay abstract Autistic adults experience difficulties finding and keeping employment. However, research investigating reasons that might explain this difficulty produce mixed results. We gave a survey to 2449 autistic adults and used a statistic method to group them based on their employment status over 8 years. We identified four employment groups that best captured the experiences of autistic adults; this included a group that experienced stable unemployment, a group that experienced stable employment, a group that had high employment that reduced over time, and a group whose employment increased over the 8 years. Further analysis showed that those with fewer autistic traits, younger age, male gender, higher education, later diagnosis age and no co-occurring conditions were more likely to have stable employment. People whose employment changed over time were more likely to have a higher level of education than the stable unemployment group, and those in the increasing employment group were younger age and had no co-occurring conditions. These findings help us better understand that not all autistic adults' experiences of employment are the same, which helps focus where employment programmes and support may be most needed, for example, people who identify as women or have a co-occurring condition.
Frontopolar cortex (FPC) is a large, anterior sub-region of prefrontal cortex found in both humans and non-human primates (NHPs) and is thought to support monitoring the value of switching between alternative goals. However, the neuronal mechanisms underlying this function are unclear. Here we used multielectrode arrays to record the local field potentials (LFPs) in the FPC of two macaques performing a Wisconsin Card Sorting Test analogue and found that bursts of gamma and beta in FPC tracked counterfactual not current rule value. Moreover, we show that brief high-frequency microstimulation to a single trial causally affects both LFP activity in FPC, as well as rule-guided decision-making across successive trials. Following stimulation of FPC we observed reduced exploration of the counterfactual rule pre-rule-change, as well as a delayed adaptation to the newly relevant following post-rule-change. A similar, multi-trial time-course disturbance to beta and gamma activity within FPC was also induced following single-trial microstimulation. These findings conclusively link neuronal activity in FPC with behavioural monitoring of the value of counterfactual rules and provide neural mechanistic insights into how FPC supports rule-based decision-making. ### Competing Interest Statement The authors have declared no competing interest.
Background The Australian population aged 70 and above is increasing and imposing new challenges for policy makers and providers to deliver accessible, appropriate and affordable health care. We examine pre-COVID patterns of health loss between 1990 and 2019 to inform policies and practices. Methods Using the standardised methodology framework and analytical strategies from GBD 2019 methodologies, we estimated mortality, causes of death, years of life lost (YLLs), years lived with disability (YLDs), disability-adjusted life years (DALYs), life expectancy at age 70 and above (LE-70), and healthy life expectancy (HALE-70) in Australia comparing them globally and with high socio-demographic index (SDI) groups. Findings DALY rates have been improving steadily over the past 30 years among Australians aged 70 and above. Decreases in DALY rates were primarily attributed to a fall in YLLs attributable to cardiovascular diseases (60%) and chronic respiratory disorders (30.2%) and transport injuries (56.9%), while the non-fatal burden remained stable from 1990 to 2019. According to the DALY rates, the top five leading causes are ischemic heart disease, Alzheimer's disease, COPD, stroke, and falls, where falls exhibited the largest increase since 1990. Interpretation This study provides an in-depth report on the main causes of mortality and disability in Australia's population aged 70 and above. It sheds light on the shifts in burden over three decades, emphasising the need for the Australian health system to enhance its readiness in addressing the escalating demands of an ageing population. These findings establish pre-COVID baseline estimates for Australia's population aged 70 and above, informing healthcare preparedness. Copyright (c) 2024 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
We aimed to quantify the risk, mortality, and burden of suicide among autistic persons. We searched PubMed, Embase, and PsycINFO on 5th April 2023 for sources reporting the relative risk (RR) of suicide or suicide attempt among autistic persons (PROSPERO registration: CRD42021265313). Autism spectrum prevalence and suicide mortality and years of life lost (YLLs), were sourced from the Global Burden of Disease Study 2021. RRs pooled via meta-regression and health metrics estimates were used to estimate the excess suicide mortality and YLLs among autistic persons. We sourced 983 unique studies of which ten studies met inclusion criteria, consisting of 10.4 million persons. The pooled RR for suicide for autistic persons was 2·85 (95% UI: 2·05–4·03), which was significantly higher for autistic females than autistic males. No evidence of publication bias was detected via inspection of funnel plot and Egger's test. Globally, we estimated 13 400 excess suicide deaths among autistic persons in 2021, equating to 1·8% of all suicide deaths and 621 000 excess YLLs. Studies were limited in number and geographical coverage. Effective suicide prevention strategies for autistic persons may substantially reduce the fatal burden of suicides globally and reduce the health burden experienced within this population.
Although negative anticipatory emotions are typically seen as risk factors for poorer psychological outcomes over COVID-19, emotion theorists suggest that this risk may be attenuated if balanced by the experience of positive emotion. Thus, the current study examined whether interactions between positive and negative anticipatory emotions were concurrently associated with psychological distress and greater personal wellbeing/posttraumatic growth (PTG) at three distinct periods (i.e., pre-lockdown, during lockdown, post-lockdown), and whether associations varied by these three COVID-19 time periods. The study utilizes two large longitudinal Australian samples, surveyed in 2020 prior to, during, and after a strict 4-month lockdown that occurred in Australia. Overall, positive emotions attenuated the adverse psychological outcomes arising from higher levels of negative emotion (i.e., higher psychological distress and lower personal wellbeing). Observed effects varied according to COVID-19 threat exposure. Specifically, the interaction was significantly associated with psychological distress prior to the lockdown for Sample 2, and during the lockdown for both samples. The interaction was significantly associated with wellbeing (Sample 2) prior to, and during, the lockdown but only marginally associated post-lockdown. The interaction, however, was not significantly associated with PTG (Sample 1). The results suggest that it is valuable for future research to consider greater emotional complexity (i.e., mixed emotions) over COVID-19, and other stressors more generally, to encompass a more nuanced understanding of resilience.
When multiple items are held in short-term memory, cues that retrospectively prioritise one item over another (retro-cues) can facilitate subsequent recall. However, the neural and computational underpinnings of this effect are poorly understood. One recent study recorded neural signals in the macaque lateral prefrontal cortex (LPFC) during a retro-cueing task, contrasting delay-period activity before (pre-cue) and after (post-cue) retrocue onset. They reported that in the pre-cue delay, the individual stimuli were maintained in independent subspaces of neural population activity, whereas in the post-cue delay, the prioritised items were rotated into a common subspace, potentially allowing a common readout mechanism. To understand how such representational transitions can be learnt through error minimisation, we trained recurrent neural networks (RNNs) with supervision to perform an equivalent cued-recall task. RNNs were presented with two inputs denoting conjunctive colour-location stimuli, followed by a pre-cue memory delay, a location retrocue, and a post-cue delay. We found that the orthogonal-to-parallel geometry transformation observed in the macaque LPFC emerged naturally in RNNs trained to perform the task. Interestingly, the parallel geometry only developed when the cued information was required to be maintained in short-term memory for several cycles before readout, suggesting that it might confer robustness during maintenance. We extend these findings by analysing the learning dynamics and connectivity patterns of the RNNs, as well as the behaviour of models trained with probabilistic cues, allowing us to make predictions for future studies. Overall, our findings are consistent with recent theoretical accounts which propose that retrocues transform the prioritised memory items into a prospective, action-oriented format.