Environmental dynamics shape perceptual decision bias.

To interpret the sensory environment, the brain combines ambiguous sensory measurements with knowledge that reflects context-specific prior experience. But environmental contexts can change abruptly and unpredictably, resulting in uncertainty about the current context. Here we address two questions: how should context-specific prior knowledge optimally guide the interpretation of sensory stimuli in changing environments, and do human decision-making strategies resemble this optimum? We probe these questions with a task in which subjects report the orientation of ambiguous visual stimuli that were drawn from three dynamically switching distributions, representing different environmental contexts. We derive predictions for an ideal Bayesian observer that leverages knowledge about the statistical structure of the task to maximize decision accuracy, including knowledge about the dynamics of the environment. We show that its decisions are biased by the dynamically changing task context. The magnitude of this decision bias depends on the observer's continually evolving belief about the current context. The model therefore not only predicts that decision bias will grow as the context is indicated more reliably, but also as the stability of the environment increases, and as the number of trials since the last context switch grows. Analysis of human choice data validates all three predictions, suggesting that the brain leverages knowledge of the statistical structure of environmental change when interpreting ambiguous sensory signals.

Business as unusual: medical oncology services adapt and deliver during COVID-19.

BACKGROUND: The COVID-19 pandemic has challenged cancer care globally, introducing resource limitations and competing risks into clinical practice. AIMS: To describe the COVID-19 impact on medical oncology care provision in an Australian setting. METHODS: Calvary Mater Newcastle and Newcastle Private Hospital medical oncology data from 1 February to 31 April 2019 versus 2020 were retrospectively analysed. RESULTS: Three hundred and sixty-four inpatient admissions occurred in 2020, 21% less than in 2019. Total inpatient days decreased by 22% (2842 vs 2203). April was most impacted (36% and 44% fewer admissions and inpatient days respectively). Mean length of stay remained unchanged (6.4 vs 6.2 days, P = 0.7). In all, 5072 outpatient consultations were conducted, including 417 new-patient consultations (4% and 6% increase on 2019 respectively). Telephone consultations (0 vs 1380) replaced one-quarter of face-to-face consultations (4859 vs 3623, -25%), with minimal telehealth use (6 vs 69). Day Treatment Centre encounters remained stable (3751 vs 3444, -8%). The proportion of new patients planned for palliative treatment decreased (35% vs 28%, P = 0.04), observation increased (16% vs 23%, P = 0.04) and curative intent treatment was unchanged (both 41%). Recruiting clinical trials decreased by one-third (45 vs 30), two trials were activated (vs 5 in 2019) and 45% fewer patients consented to trial participation (62 vs 34). CONCLUSION: Our medical oncology teams adapted rapidly to COVID-19 with significant changes to care provision, including fewer hospital admissions, a notable transition to telephone-based outpatient clinics and reduced clinical trial activity. The continuum of care was largely defended despite pandemic considerations and growing service volumes.

Treatment of pancreatic insufficiency using pancreatic extract in patients with advanced pancreatic cancer: a pilot study (PICNIC).

PURPOSE: Survival with advanced pancreatic cancer is less than 12 months. Pancreatic exocrine insufficiency may contribute to pancreatic cancer-related cachexia, via nutrient malabsorption. We aimed to determine the feasibility of prescribing pancreatic extract (Creon®) for patients with advanced pancreatic cancer. METHODS: Patients with advanced pancreatic cancer, without frank malabsorption, were randomised in this feasibility study to pancreatic extract 50,000 units with meals and 25,000 units with snacks, or placebo. Standardised dietary advice was given. Anti-cancer and supportive care treatments were permitted. Outcomes included weight, body mass index (BMI), quality of life (QLQC30, PAN26), survival and nutritional assessment (PG-SGA). RESULTS: Eighteen patients were randomised before study closure due to slow recruitment. Baseline characteristics were well matched. Weight loss prior to randomisation was numerically greater in the pancreatic extract group (mean 0.7 vs 2.2 kg). Weight loss was numerically greater in the placebo group, however not significantly. No differences in BMI or nutrition score were seen. Quality of life did not differ between study groups. Median overall survival was 17 (95% CI 8.1-48.7) weeks in the control group, and 67.6 (95% CI 14.1-98.4) weeks in the pancreatic extract group (p = 0.1063). Only 17% (18/106) of potentially eligible patients were recruited, related to patient/family reluctance, rapid clinical deterioration and patients already prescribed pancreatic extract. A moderate pill burden was noted. CONCLUSION: Despite intriguing survival results, this study was not sufficiently feasible to proceed to a fully powered comparative study. A multi-centre study would be required to exclude a significant difference in outcomes.

A Randomized Controlled Trial of a Nurse-Led Supportive Care Package (SurvivorCare) for Survivors of Colorectal Cancer.

INTRODUCTION: Colorectal cancer (CRC) and its treatments can cause distressing sequelae. We conducted a multicenter randomized controlled trial aiming to improve psychological distress, supportive care needs (SCNs), and quality of life (QOL) of patients with CRC. The intervention, called SurvivorCare (SC), comprised educational materials, needs assessment, survivorship care plan, end-of-treatment session, and three follow-up telephone calls. METHODS: At the end of treatment for stage I-III CRC, eligible patients were randomized 1:1 to usual care (UC) or to UC plus SC. Distress (Brief Symptom Inventory 18), SCNs (Cancer Survivors' Unmet Needs measure), and QOL (European Organization for Research and Treatment of Cancer [EORTC] QOL questionnaires C30 and EORTC CRC module CR29) were assessed at baseline and at 2 and 6 months (follow-up 1 [FU1] and FU2, respectively). The primary hypothesis was that SC would have a beneficial effect on distress at FU1. The secondary hypotheses were that SC would have a beneficial effect on (a) SCN and QOL at FU1 and on (b) distress, SCNs, and QOL at FU2. A total of 15 items assessed experience of care. RESULTS: Of 221 patients randomly assigned, 4 were ineligible for the study and 1 was lost to FU, leaving 110 in the UC group and 106 in the SC group. Patients' characteristics included the following: median age, 64 years; men, 52%; colon cancer, 56%; rectal cancer, 35%; overlapping sites of disease, 10%; stage I disease, 7%; stage II, 22%; stage III, 71%. Baseline distress and QOL scores were similar to population norms. Between-group differences in distress at FU1 (primary outcome) and at FU2, and SCNs and QOL at FU1 and FU2 were small and nonsignificant. Patients in the SC group were more satisfied with survivorship care than those in the UC group (significant differences on 10 of 15 items). CONCLUSION: The addition of SC to UC did not have a beneficial effect on distress, SCNs, or QOL outcomes, but patients in the SC group were more satisfied with care. IMPLICATIONS FOR PRACTICE: Some survivors of colorectal cancer report distressing effects after completing treatment. Strategies to identify and respond to survivors' issues are needed. In a randomized controlled trial, the addition of a nurse-led supportive care package (SurvivorCare) to usual post-treatment care did not impact survivors' distress, quality of life, or unmet needs. However, patients receiving the SurvivorCare intervention were more satisfied with survivorship care. Factors for consideration in the design of subsequent studies are discussed.

Abstract deliberation by visuomotor neurons in prefrontal cortex.

During visually guided behavior, the prefrontal cortex plays a pivotal role in mapping sensory inputs onto appropriate motor plans. When the sensory input is ambiguous, this involves deliberation. It is not known whether the deliberation is implemented as a competition between possible stimulus interpretations or between possible motor plans. Here we study neural population activity in the prefrontal cortex of macaque monkeys trained to flexibly report perceptual judgments of ambiguous visual stimuli. We find that the population activity initially represents the formation of a perceptual choice before transitioning into the representation of the motor plan. Stimulus strength and prior expectations both bear on the formation of the perceptual choice, but not on the formation of the action plan. These results suggest that prefrontal circuits involved in action selection are also used for the deliberation of abstract propositions divorced from a specific motor plan, thus providing a crucial mechanism for abstract reasoning.

Primary visual cortex straightens natural video trajectories.

Many sensory-driven behaviors rely on predictions about future states of the environment. Visual input typically evolves along complex temporal trajectories that are difficult to extrapolate. We test the hypothesis that spatial processing mechanisms in the early visual system facilitate prediction by constructing neural representations that follow straighter temporal trajectories. We recorded V1 population activity in anesthetized macaques while presenting static frames taken from brief video clips, and developed a procedure to measure the curvature of the associated neural population trajectory. We found that V1 populations straighten naturally occurring image sequences, but entangle artificial sequences that contain unnatural temporal transformations. We show that these effects arise in part from computational mechanisms that underlie the stimulus selectivity of V1 cells. Together, our findings reveal that the early visual system uses a set of specialized computations to build representations that can support prediction in the natural environment.

Phase I study of orally administered 14Carbon-isotope labelled-vistusertib (AZD2014), a dual TORC1/2 kinase inhibitor, to assess the absorption, metabolism, excretion, and pharmacokinetics in patients with advanced solid malignancies.

PURPOSE: Vistusertib is an orally bioavailable dual target of rapamycin complex (TORC) 1/2 kinase inhibitor currently under clinical investigation in various solid tumour and haematological malignancy settings. The pharmacokinetic, metabolic and excretion profiles of 14Carbon-isotope (14C)-labelled vistusertib were characterised in this open-label phase I patient study. METHODS: Four patients with advanced solid malignancies received a single oral solution dose of 14C-labelled vistusertib. Blood, urine, faeces, and saliva samples were collected at various time points during the 8-day in-patient period of the study. Safety and preliminary efficacy were also assessed. RESULTS: 14C-labelled vistusertib was rapidly absorbed following administration (time to maximum concentration (Tmax) < 1.2 h in all subjects). Overall, > 90% of radioactivity was recovered with the majority recovered as metabolites in faeces (on average 80% vs. 12% recovered in urine). The majority of circulating radioactivity (~ 78%) is unchanged vistusertib. Various morpholine-ring oxidation metabolites and an N-methylamide circulate at low concentrations [each < 10% area under the concentration-time curve from zero to infinity (AUC0-∞)]. No new or unexpected safety findings were observed; the most common adverse events were nausea and stomatitis. CONCLUSIONS: The pharmacokinetic (PK) profile of vistusertib is similar to previous studies using the same dosing regimen in solid malignancy patients. The majority of vistusertib elimination occurred via hepatic metabolic routes.

The Ketogenic Diet Alters the Hypoxic Response and Affects Expression of Proteins Associated with Angiogenesis, Invasive Potential and Vascular Permeability in a Mouse Glioma Model.

BACKGROUND: The successful treatment of malignant gliomas remains a challenge despite the current standard of care, which consists of surgery, radiation and temozolomide. Advances in the survival of brain cancer patients require the design of new therapeutic approaches that take advantage of common phenotypes such as the altered metabolism found in cancer cells. It has therefore been postulated that the high-fat, low-carbohydrate, adequate protein ketogenic diet (KD) may be useful in the treatment of brain tumors. We have demonstrated that the KD enhances survival and potentiates standard therapy in a mouse model of malignant glioma, yet the mechanisms are not fully understood. METHODS: To explore the effects of the KD on various aspects of tumor growth and progression, we used the immunocompetent, syngeneic GL261-Luc2 mouse model of malignant glioma. RESULTS: Tumors from animals maintained on KD showed reduced expression of the hypoxia marker carbonic anhydrase 9, hypoxia inducible factor 1-alpha, and decreased activation of nuclear factor kappa B. Additionally, tumors from animals maintained on KD had reduced tumor microvasculature and decreased expression of vascular endothelial growth factor receptor 2, matrix metalloproteinase-2 and vimentin. Peritumoral edema was significantly reduced in animals fed the KD and protein analyses showed altered expression of zona occludens-1 and aquaporin-4. CONCLUSIONS: The KD directly or indirectly alters the expression of several proteins involved in malignant progression and may be a useful tool for the treatment of gliomas.