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Predictive inference and error-driven learning are critical to optimal performance across many different contexts. However, the specific context determines the informativeness of errors in updating predictions. In this study, participants experienced two changing, unsignalled contexts with opposite optimal responses to errors; the change-point context, where errors were informative, and the oddball context, where they were not. The changes to the context occurred under two task structures: 1) a fixed task structure, with consecutive blocks of each context, and 2) a random task structure, with the context randomly selected for each new block. We modelled participants' performance using a Hierarchical Gaussian Filter (HGF) model. We found that performance was greater in the oddball than change-point context, with more accurate and precise estimates. The estimates from the fixed task structure were also more precise than those in the random task structure. We showed that consistency in context can improve precision.

Temporal and spectral sound information is processed asymmetrically in the brain with the left-hemisphere showing an advantage for processing the former and the right-hemisphere for the latter. Using monaural sound presentation we demonstrate a context and ability dependent ear-asymmetry in brain measures of temporal change detection. Our measure of temporal processing ability was a gap-detection task quantifying the smallest silent gap in a sound that participants could reliably detect. Our brain measure was the size of the mismatch-negativity (MMN) auditory event-related potential elicited to infrequently presented gap sounds. The MMN indexes discrimination ability and is automatically generated when the brain detects a change in a repeating pattern of sound. MMN was elicited in unattended sequences of infrequent gap-sounds presented among regular no-gap sounds. In Study 1, participants with low gap-detection thresholds (good ability) produced a significantly larger MMN to gap sounds when sequences were presented monaurally to the right-ear than to the left-ear. In Study 2, we not only replicated a right-ear-advantage for MMN in silence in good temporal processors, but also showed that this is reversed to a significant left-ear-advantage for MMN when the same sounds are presented against a background of constant low-level noise. In both studies, poor discriminators showed no ear-advantage, and in Study 2, exhibited no differential sensitivity of the ears to noise. We conclude that these data reveal a context and ability-dependent asymmetry in processing temporal information in non-speech sounds. (Contains 4 tables and 6 figures.)

Background and Hypothesis Differences in sound relevance filtering in schizophrenia are proposed to represent a key index of biological changes in brain function in the illness. This study featured a computational modeling approach to test the hypothesis that processing differences might already be evident in first-episode, becoming more pronounced in the established illness. Study Design Auditory event-related potentials to a typical oddball sequence (rare pitch deviations amongst regular sounds) were recorded from 90 persons with schizophrenia-spectrum disorders (40 first-episode schizophrenia-spectrum, 50 established illness) and age-matched healthy controls. The data were analyzed using dynamic causal modeling to identify the changes in effective connectivity that best explained group differences. Study Results Group differences were linked to intrinsic (within brain region) connectivity changes. In activity-dependent measures these were restricted to the left auditory cortex in first-episode schizophrenia-spectrum but were more widespread in the established illness. Modeling suggested that both established illness and first-episode schizophrenia-spectrum groups expressed significantly lower inhibition of inhibitory interneuron activity and altered gain on superficial pyramidal cells with the data indicative of differences in both putative N -methyl- d -aspartate glutamate receptor activity-dependent plasticity and classic neuromodulation. Conclusions The study provides further support for the notion that examining the ability to alter responsiveness to structured sound sequences in schizophrenia and first-episode schizophrenia-spectrum could be informative to uncovering the nature and progression of changes in brain function during the illness. Furthermore, modeling suggested that limited differences present at first-episode schizophrenia-spectrum may become more expansive with illness progression. [ABSTRACT FROM AUTHOR]

Reduced mismatch negativity (MMN), a robust finding in schizophrenia, has prompted interest in MMN as a preclinical biomarker of schizophrenia. The rat brain can generate human‐like mismatch responses (MMRs) which therefore enables the exploration of the neurobiology of reduced MMRs. Given epidemiological evidence that two developmental factors, maternal infection and adolescent cannabis use, increase the risk of schizophrenia, we determined the effect of these two developmental risk factors on rat MMR amplitude in different auditory contexts. MMRs were assessed in awake adult male and female Wistar rats that were offspring of pregnant dams treated with either a viral infection mimetic (poly I:C) inducing maternal immune activation (MIA) or saline control. In adolescence, subgroups of the prenatal treatment groups were exposed to either a synthetic cannabinoid (adolescent cannabinoid exposure: ACE) or vehicle. The context under which MMRs were obtained was manipulated by employing two different oddball paradigms, one that manipulated the physical difference between rare and common auditory stimuli, and another that manipulated the probability of the rare stimulus. The design of the multiple stimulus sequences across the two paradigms also allowed an investigation of context on MMRs to two identical stimulus sequences. Male offspring exposed to each of the risk factors for schizophrenia (MIA, ACE or both) showed a reduction in MMR, which was evident only in the probability paradigm, with no effects seen in the physical difference. Our findings highlight the importance of contextual factors induced by paradigm manipulations and sex for modeling schizophrenia‐like MMN impairments in rats. Our findings demonstrate a schizophrenia‐like reduction in the size of the mismatch responses in a developmental risk factor rat model, a novel finding as the previous research have shown similar effects in pharmacologically manipulated animal models only. The current results underscore the importance of paradigm in utilizing the mismatch negativity as a biomarker for schizophrenia in future studies. [ABSTRACT FROM AUTHOR]

Rationale: Mismatch negativity (MMN) is a candidate endophenotype for schizophrenia subserved by N-methyl-D-aspartate receptor (NMDAR) function and there is increasing evidence that prolonged cannabis use adversely affects MMN generation. Few human studies have investigated the acute effects of cannabinoids on brain-based biomarkers of NMDAR function and synaptic plasticity. Objectives: The current study investigated the acute effects of Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) alone and in combination on the mismatch negativity (MMN). Methods: In a randomised, double-blind, crossover placebo-controlled study, 18 frequent and 18 less-frequent cannabis users underwent 5 randomised drug sessions administered via vaporiser: (1) placebo; (2) THC 8 mg; (3) CBD 400 mg; (4) THC 8 mg + CBD 4 mg [THC + CBDlow]; (5) THC 12 mg + CBD 400 mg [THC + CBDhigh]. Participants completed a multifeature MMN auditory oddball paradigm with duration, frequency and intensity deviants (6% each). Results: Relative to placebo, both THC and CBD were observed to increase duration and intensity MMN amplitude in less-frequent users, and THC also increased frequency MMN in this group. The addition of low-dose CBD added to THC attenuated the effect of THC on duration and intensity MMN amplitude in less-frequent users. The same pattern of effects was observed following high-dose CBD added to THC on duration and frequency MMN in frequent users. Conclusions: The pattern of effects following CBD combined with THC on MMN may be subserved by different underlying neurobiological interactions within the endocannabinoid system that vary as a function of prior cannabis exposure. These results highlight the complex interplay between the acute effects of exogenous cannabinoids and NMDAR function. Further research is needed to determine how this process normalises after the acute effects dissipate and following repeated acute exposure. [ABSTRACT FROM AUTHOR]

Previous research demonstrates that developing a STEM identity is key to students achieving long-term engagement with STEM. This paper reports on a 10-week intervention combining the use of mentors with real-world problemsolving activities with the aim to contribute to girls' STEM identity formation and improve their interest and participation in STEM. The intervention was delivered in nine schools to 200 girls aged 13-16 in the Hunter region, Australia, with the aid of 31 mentors who supported them as they worked in small groups. All participants were invited to complete post-intervention group interviews [30 interviews, 3-6 per group] to gain insight into their perceptions of the importance of STEM subjects, careers, and skills; and to determine whether our program had any effect on those perceptions. Girls demonstrated a sophisticated understanding of societal influences that impacted their relationship to, and likelihood of pursuing STEM careers, including certain barriers such as gender stereotypes. Girls found the most useful elements of the intervention focused on contextualising how STEM learning could be applied in practice. Incorporating problem-based activities into STEM learning and providing opportunities for girls to see women working in real-life STEM roles emerged as key factors in the development of STEM identities. [ABSTRACT FROM AUTHOR]