Deficits in memory metacognitive efficiency in late adulthood are related to distinct brain profile.

The tendency of falsely remembering events that did not happen in the past increases with age. This is particularly evident in cases in which features presented at study are re-presented at test in a recombined constellation (termed rearranged pairs). Interestingly, older adults also express high confidence in such false memories, a tendency that may indicate reduced metacognitive efficiency. Within an existing cohort study, we aimed at investigating age-related differences in memory metacognitive efficiency (as measured by meta d' ratio) in a sample of 1522 older adults and 397 young adults. The analysis showed an age-related deficit in metacognition which was more pronounced for rearranged pairs than for new pairs. We then explored associations between cortical thickness and memory metacognitive efficiency for rearranged pairs in a subsample of 231 older adults. By using partial least square analysis, we found that a multivariate profile composed by ventromedial prefrontal cortex, insula, and parahippocampal cortex was uniquely associated with between-person differences in memory metacognitive efficiency. These results suggest that the impairment in memory metacognitive efficiency for false alarms is a distinct age-related deficit, above and beyond a general age-related decline in memory discrimination, and that it is associated with brain regions involved in metacognitive processes.

Signed and unsigned effects of prediction error on memory: Is it a matter of choice?

Adaptive decision-making is governed by at least two types of memory processes. On the one hand, learned predictions through integrating multiple experiences, and on the other hand, one-shot episodic memories. These two processes interact, and predictions - particularly prediction errors - influence how episodic memories are encoded. However, studies using computational models disagree on the exact shape of this relationship, with some findings showing an effect of signed prediction errors and others showing an effect of unsigned prediction errors on episodic memory. We argue that the choice-confirmation bias, which reflects stronger learning from choice-confirming compared to disconfirming outcomes, could explain these seemingly diverging results. Our perspective implies that the influence of prediction errors on episodic encoding critically depends on whether people can freely choose between options (i.e., instrumental learning tasks) or not (Pavlovian learning tasks). The choice-confirmation bias on memory encoding might have evolved to prioritize memory representations that optimize reward-guided decision-making. We conclude by discussing open issues and implications for future studies.

The effect of prediction error on episodic memory encoding is modulated by the outcome of the predictions.

Expectations can lead to prediction errors of varying degrees depending on the extent to which the information encountered in the environment conforms with prior knowledge. While there is strong evidence on the computationally specific effects of such prediction errors on learning, relatively less evidence is available regarding their effects on episodic memory. Here, we had participants work on a task in which they learned context/object-category associations of different strengths based on the outcomes of their predictions. We then used a reinforcement learning model to derive subject-specific trial-to-trial estimates of prediction error at encoding and link it to subsequent recognition memory. Results showed that model-derived prediction errors at encoding influenced subsequent memory as a function of the outcome of participants' predictions (correct vs. incorrect). When participants correctly predicted the object category, stronger prediction errors (as a consequence of weak expectations) led to enhanced memory. In contrast, when participants incorrectly predicted the object category, stronger prediction errors (as a consequence of strong expectations) led to impaired memory. These results highlight the important moderating role of choice outcome that may be related to interactions between the hippocampal and striatal dopaminergic systems.

Not what u expect: Effects of prediction errors on item memory.

The characterization of the relationship between predictions and one-shot episodic encoding poses an important challenge for memory research. On the one hand, events that are compatible with our previous knowledge are thought to be remembered better than incompatible ones. On the other hand, unexpected situations, by virtue of their novelty, are known to cause enhanced learning. Several theoretical accounts try to solve this apparent paradox by conceptualizing prediction error (PE) as a continuum ranging from low PE (for expectation-matching events) to high PE (for expectation-mismatching ones). Under such a framework, the relationship between PE and memory encoding would be described by a U-shape function with higher memory performance for extreme levels of PE and lower memory for middle levels of PE. In this study, we tested the framework by using a gradual manipulation of the strength of association between scenes and objects to render different levels of PE and then tested for item memory of the (mis)matching events. In two experiments, in contrast to what was anticipated, recognition memory for object identity followed an inverted U-shape as a function of PE, with higher performance for intermediate levels of PE. Furthermore, in two additional experiments, we showed the relevance of explicit predictions at encoding to reveal such an inverted U pattern, thus providing the boundary conditions of the effect. We discussed our findings in light of existing literature relating PE and episodic memory, pointing out the potential roles of uncertainty in the environment, and the importance of the cognitive operations underlying encoding tasks. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Distinct multivariate structural brain profiles are related to variations in short- and long-delay memory consolidation across children and young adults.

From early to middle childhood, brain regions that underlie memory consolidation undergo profound maturational changes. However, there is little empirical investigation that directly relates age-related differences in brain structural measures to memory consolidation processes. The present study examined memory consolidation of intentionally studied object-location associations after one night of sleep (short delay) and after two weeks (long delay) in normally developing 5-to-7-year-old children (n = 50) and young adults (n = 39). Behavioural differences in memory retention rate were related to structural brain measures. Our results showed that children, in comparison to young adults, retained correctly learnt object-location associations less robustly over short and long delay. Moreover, using partial least squares correlation method, a unique multivariate profile comprised of specific neocortical (prefrontal, parietal, and occipital), cerebellar, and hippocampal head and subfield structures in the body was found to be associated with variation in short-delay memory retention. A different multivariate profile comprised of a reduced set of brain structures, mainly consisting of neocortical (prefrontal, parietal, and occipital), hippocampal head, and selective hippocampal subfield structures (CA1-2 and subiculum) was associated with variation in long-delay memory retention. Taken together, the results suggest that multivariate structural pattern of unique sets of brain regions are related to variations in short- and long-delay memory consolidation across children and young adults.

Plan quality and consistency in spine radiosurgery treatment planning: comparison between automatic treatment planning with Elements Spine SRS and manual inverse planning with Varian Eclipse.

Spine radiosurgery treatment planning can be a challenging task since a high radiation dose is delivered to target volumes close to the spinal cord, therefore a steep dose gradient is required. Plan quality is greatly influenced by the planner skills, so automatic treatment planning has been proposed to overcome this issue and assure high-quality plans. The Brainlab Elements Spine SRS treatment planning system is specially designed for spine radiosurgery treatments. It is an automatic treatment planning system that works through predefined protocols, with minimal planner interaction required. In this work, we evaluated the plan quality and consistency among the planners within the same institution when using the Elements Spine SRS compared to manual inverse planning with the Varian Eclipse system. Six planners produced a plan for 3 sample target volumes representing different spine metastases in the thoracic region using both treatment planning systems. Dose prescription was 16 Gy in a single fraction, at more than 80% of the target volume. The most important organ at risk was the spinal canal. The dose constraint was V10 Gy < 0.35 cm3. High dose spillage outside the target volume, the homogeneity index, the Paddick conformity index and the number of monitor units were also evaluated. The mean dose to the target volumes in the Elements Spine SRS plans were consistently higher by 0.8 Gy to 1.5 Gy and the maximum dose to the target volumes were consistently higher by 1.8 Gy to 3.1 Gy. Spinal cord sparing was comparable to the Eclipse plans. However, the number of monitor units was greatly reduced, up to 2270 monitor units less. No difference was found in plan quality variability among the planners.

The detrimental effects of mood on prospective memory are modulated by age.

Everyday fluctuations in mood can influence our ability to remember to carry out intentions (prospective memory [PM]). Theories of mood-cognition interaction make differing predictions about the effects of positive and negative mood states on cognition that may change in aging. To test these predictions, we looked at the effects of age and induced mood on different types of PM tasks. Results showed that on a task which required constant attentional monitoring (event-based PM) young adults' performance was impaired by negative mood, whereas older adults' performance was not influenced by mood. Further analyses indicated that the deleterious effects of negative mood states in young participants were related to decreased monitoring. In another task which required more intermittent monitoring (time-based PM), older adults' performance actually improved under positive mood, whereas young adults showed no effect of mood. Contrary to predictions, these age differences were not related to improved emotion regulation in old age. We conclude that young adults are more likely than older to show PM failures caused by negative mood. Future research priorities are outlined to better understand the motivational and task characteristics which influence this phenomenon. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Effective dose and image quality for intraoperative imaging with a cone-beam CT and a mobile multi-slice CT in spinal surgery: A phantom study.

PURPOSE: To compare the effective dose (ED) and image quality (IQ) of O-arm cone-beam CT (Medtronic, Minneapolis, MN, USA) and Airo multi-slice CT (Brainlab AG, Munich, Germany) for intraoperative-CT (i-CT) in spinal surgery. METHODS: The manufacturer-defined protocols available in the O-arm and Airo systems for three-dimensional lumbar spine imaging were compared. Organ dose was measured both with thermo-luminescent dosimeters and GafChromic films in the Alderson RadiationTherapy anthropomorphic phantom. A subjective analysis was performed by neurosurgeons to compare the clinical IQ of the anthropomorphic phantom images acquired with the different i-CT systems and imaging protocols. Image uniformity, noise, contrast-to-noise-ratio (CNR), and spatial resolution were additionally assessed with the Catphan 504 phantom. RESULTS: O-arm i-CT caused 56% larger ED than Airo due to the high definition (HD) imaging protocol. The noise was larger for O-arm images leading to a lower CNR than that measured for Airo. Moreover, scattering and beam hardening effects were observed in the O-arm images. Better spatial resolution was measured for the O-arm system (9 lp/cm) than for Airo (4 lp/cm). For all the investigated protocols, O-arm was found to be better for identifying anatomical features important for accurate pedicle screw positioning. CONCLUSIONS: According to phantom measurements, the HD protocol of O-arm offered better clinical IQ than Airo but larger ED. The larger noise of O-arm images did not compromise the clinical IQ while the superior spatial resolution of this system allowed a better visibility of anatomical features important for pedicle screw positioning in the lumbar region.

Patient-based low dose cone beam CT acquisition settings for prostate image-guided radiotherapy treatments on a Varian TrueBeam linear accelerator.

OBJECTIVE: To evaluate the performance of low dose cone beam CT (CBCT) acquisition protocols for image-guided radiotherapy of prostate cancer. METHODS: CBCT images of patients undergoing prostate cancer radiotherapy were acquired with the settings currently used in our department and two low dose settings at 50% and 63% lower exposure. Four experienced radiation oncologists and two radiation therapy technologists graded the images on five image quality characteristics. The scores were analysed through Visual Grading Regression, using the acquisition settings and the patient size as covariates. RESULTS: The low dose acquisition settings have no impact on the image quality for patients with body profile length at hip level below 100 cm. CONCLUSIONS: A reduction of about 60% of the dose is feasible for patients with size below 100 cm. The visibility of low contrast features can be compromised if using the low dose acquisition settings for patients with hip size above 100 cm. ADVANCES IN KNOWLEDGE: Low dose CBCT acquisition protocols for the pelvis, based on subjective evaluation of patient images.

A simple method for low-contrast detectability, image quality and dose optimisation with CT iterative reconstruction algorithms and model observers.

BACKGROUND: The aim of this work was to evaluate detection of low-contrast objects and image quality in computed tomography (CT) phantom images acquired at different tube loadings (i.e. mAs) and reconstructed with different algorithms, in order to find appropriate settings to reduce the dose to the patient without any image detriment. METHODS: Images of supraslice low-contrast objects of a CT phantom were acquired using different mAs values. Images were reconstructed using filtered back projection (FBP), hybrid and iterative model-based methods. Image quality parameters were evaluated in terms of modulation transfer function; noise, and uniformity using two software resources. For the definition of low-contrast detectability, studies based on both human (i.e. four-alternative forced-choice test) and model observers were performed across the various images. RESULTS: Compared to FBP, image quality parameters were improved by using iterative reconstruction (IR) algorithms. In particular, IR model-based methods provided a 60% noise reduction and a 70% dose reduction, preserving image quality and low-contrast detectability for human radiological evaluation. According to the model observer, the diameters of the minimum detectable detail were around 2 mm (up to 100 mAs). Below 100 mAs, the model observer was unable to provide a result. CONCLUSION: IR methods improve CT protocol quality, providing a potential dose reduction while maintaining a good image detectability. Model observer can in principle be useful to assist human performance in CT low-contrast detection tasks and in dose optimisation.

Excellent survival regardless of disease stage in patients with advanced nasopharyngeal cancer.

BACKGROUND: We present our experience in assessing the feasibility and efficacy outcomes of intensified intensity-modulated radiation therapy (IMRT) with simultaneous integrated boost (SIB) delivered to patients with nasopharyngeal carcinoma (NPC). METHODS: Between March 2009 and December 2014, 35 patients affected by advanced NPC with a median age of 53 years (range 11-77) were treated with definitive radiotherapy. Radiotherapy was delivered by helical tomotherapy with the SIB technique. The prescribed doses were 66 Gy to macroscopic disease, 60 Gy to high-risk subclinical disease, and 54 Gy to low-risk disease in 30 fractions. The daily SIB dose was 2.2 Gy to macroscopic disease. RESULTS: At the end of treatment 33 (94%) patients had obtained complete clearance of disease and 2 patients had died (1 of persistent disease after 3 months and 1 of cancer-unrelated causes after 4 months). At a median follow-up of 40 months (range 5-69), locoregional control rates at 2 and 4 years were 92.9% and 88.2%, respectively, and the overall survival after 4 years was 93.9%. The most significant acute toxicities were grade 2 and 3 mucositis (43%). No grade 3 and 4 late toxicities were observed; grade 2 xerostomia after 6 months from the end of treatment was reported in 11 patients; xerostomia toxicity decreased to grade 1 in 6/11 patients within 12 months. CONCLUSIONS: These results show that intensified IMRT with SIB is an excellent strategy offering high local control rates for NPC patients with mild acute and late toxicity.

Long-term survival in a patient with head and neck paraganglioma treated with tailored modalities for 20 years: a case report.

AIMS AND BACKGROUND: Primary paragangliomas of nasal cavity and paranasal sinus are rare conditions that could show aggressive behavior with local recurrence and metastasis development. The diagnosis of malignancy is challenging because there are no available histopathologic criteria. In these cases, the prognosis is usually poor. METHODS: We report a case of a woman with malignant paranasal sinus paragangliomas. RESULTS: The patient was treated with several surgical approaches, radiotherapy, and medical therapy for different recurrences. CONCLUSIONS: Despite the malignant behavior of the disease, this patient is still alive many years after first diagnosis.

Novel 10-fraction breast irradiation in prone and supine position: technical, dosimetric and clinical evaluation.

BACKGROUND: The aim of this study was to evaluate retrospectively the planned dose distribution and acute toxicity of adjuvant hypofractionated whole breast radiotherapy (RT) delivered in the prone vs. supine position. METHODS: Twenty-four patients were enrolled; 12 underwent adjuvant RT with a supine setup and 12 with a prone setup. We included patients according to breast volume (≥500 mL), disease stage (≤pT2/pN1), and clinical/biological features. Patients received a regimen of 35 Gy in 10 fractions for 2.5 weeks, and a concomitant boost of 3/4 Gy in 1 fraction/week. Target coverage was assessed by volume, V90, V95, V100, V103 and V105. Heart, LADCA and ipsilateral lung doses were evaluated according to volume, maximum dose, mean dose, V14, V10 and V5. We evaluated acute skin toxicity during RT, at the end of treatment, and after 1 month according to RTOG scales. RESULTS: Radiobiological equivalence was warranted with satisfactory BED values: considering α/ß = 4 for breast cancer, the 10-fraction schedule equaled 74 or 77 Gy depending on the boost dose (3 Gy vs. 4 Gy, respectively). Toxicity was low and similar for supine and prone treatments. Dose sparing was significant in the ipsilateral lung in the prone position (median Dmax: 28.7 Gy vs. 38.4 Gy; median Dmean: 0.8 Gy vs. 6.3 Gy; median V14: 0.6% vs. 13.5%; median V5: 0 vs. 19.3%, p<0.001). CONCLUSIONS: This novel 10-fraction schedule is feasible and well tolerated; the prone position allows better saving of OARs, with a statistically significant value for the ipsilateral lung.

Two different hypofractionated breast radiotherapy schedules for 113 patients with ductal carcinoma in situ: preliminary results.

AIM: To assess local control and cosmetic outcomes for two different hypofractionated radiotherapy schedules after breast-conserving surgery for ductal carcinoma in situ (DCIS). PATIENTS AND METHODS: A total of 113 breast-conserving operated patients with DCIS were treated from August 2006 to August 2011: 41 women received 46 Gy in 20 fractions of 2.3 Gy four times a week, for five weeks; the other 72 patients received 39 Gy in 13 fractions of 3 Gy four times a week for 3.5 weeks. Both schedules involved a concomitant boost to the tumor bed, with dose adjustment according to the surgical margins. RESULTS: The median follow-up is 30.5 months. Overall, the treatments were well-tolerated. The most common acute effect was erythema: grade 1 in 56.1% and 31.9% in the longer and in the shorter hypofractionated treatment, grade 2 in 9.8% and 0% of cases respectively. Late toxicity of fibrosis occurred at grade 1 in 19.6% and 15.3% respectively and at grade 2 in 0% and 2.8%. CONCLUSION: These results suggest that patients with DCIS can be safely treated with a shorter radiotherapy regimen.

Determination of the correction factors for different ionization chambers used for the calibration of the helical tomotherapy static beam.

BACKGROUND AND PURPOSE: To determine the machine-specific correction factors for three commercial ionization chambers (Exradin A1SL, PTW Semiflex and PTW PinPoint) to be applied in the dose calibration of a helical tomotherapy (HT) unit. MATERIALS AND METHODS: Machine-specific reference (msr) conditions for HT unit involved a 10 × 5 cm(2) (IEC x×y) radiation field at 85 cm SSD with the ionization chamber (IC) positioned at 10 cm depth in Virtual Water. Each msr correction factor was determined using the formalism proposed by the AAPM Task Group 148 (i.e. k(Q[HT)(TG-51])) and was compared to direct calibration of the ICs against radiochromic films, calibrated in absolute dose at our institute, following the formalism proposed by the IAEA-AAPM joint committee (i.e. [Formula: see text] ). RESULTS: TPR(20,10) values under HT msr conditions were 0.608, 0.608 and 0.615 corresponding to %dd(10)(x[HT)(Ref]) of 0.606, 0.606 and 0.613 for A1SL, Semiflex and PinPoint ICs, respectively. Based on these findings, k(Q[HT)(TG-51]) determination resulted 0.998±0.001, 0.998±0.001 and 0.991±0.002 for A1SL, Semiflex and PinPoint ICs, respectively. The [Formula: see text] correction factors obtained through direct calibration were 1.000±0.010, 1.004±0.007 and 0.998±0.006 for A1SL, Semiflex and PinPoint ICs, respectively. CONCLUSIONS: Direct calibration of ICs versus radiochromic films provided correction factors equivalent to those obtained following the TG-148 formalism. This study showed that ICs calibrated for conventional linear accelerators can be used for the calibration of the static beam delivered by a HT unit taking into account the particular reference conditions.