Suboptimal Integration of Reward Magnitude and Prior Reward Likelihood in Categorical Decisions by Monkeys

Sensory decisions may be influenced by non-sensory information regarding reward magnitude or reward likelihood. Given identical sensory information, it is more optimal to choose an option if it is a priori more likely to be correct and hence rewarded (prior reward likelihood bias), or if it yields a larger reward, given that it is the correct choice (reward magnitude bias). Here, we investigated the ability of macaque monkeys to integrate reward magnitude and prior reward likelihood information into a categorical decision about stimuli with high signal strength but variable decision uncertainty. In the asymmetric reward magnitude condition, monkeys over-adjusted their decision criterion such that they chose the highly rewarded alternative far more often than was optimal; in contrast, monkeys did not adjust their decision criterion in response to asymmetric reward likelihood. This finding shows that in this setting, monkeys did not adjust their decision criterion based on the product of reward likelihood and reward magnitude as has been reported to be the case in value-based decisions that do not involve decision uncertainty due to stimulus categorization

Orienting of Attention to Gaze Direction Cues in Rhesus Macaques: Species-Specificity, and Effects of Cue Motion and Reward Predictiveness

Primates live in complex social groups and rely on social cues to direct their attention. For example, primates react faster to an unpredictable stimulus after seeing a conspecific looking in the direction of that stimulus. In the current study we tested the specificity of facial cues (gaze direction) for orienting attention and their interaction with other cues that are known to guide attention. In particular, we tested whether macaque monkeys only respond to gaze cues from conspecifics or if the effect generalizes across species. We found an attentional advantage of conspecific faces over human and cartoon faces. Because gaze cues are often conveyed by gesture, we also explored the effect of image motion (a simulated glance) on the orienting of attention in monkeys. We found that the simulated glance did not significantly enhance the speed of orienting for monkey-face stimuli, but had a significant effect for images of human faces. Finally, because gaze cues presumably guide attention toward relevant or rewarding stimuli, we explored whether orienting of attention was modulated by reward predictiveness. When the cue predicted reward location, face, and non-face cues were effective in speeding responses toward the cued location. This effect was strongest for conspecific faces. In sum, our results suggest that while conspecific gaze cues activate an intrinsic process that reflexively directs spatial attention, its effect is relatively small in comparison to other features including motion and reward predictiveness. It is possible that gaze cues are more important for decision-making and voluntary orienting than for reflexive orienting

Scale-invariance of receptive field properties in primary visual cortex

<p>Abstract</p> <p>Background</p> <p>Our visual system enables us to recognize visual objects across a wide range of spatial scales. The neural mechanisms underlying these abilities are still poorly understood. Size- or scale-independent representation of visual objects might be supported by processing in primary visual cortex (V1). Neurons in V1 are selective for spatial frequency and thus represent visual information in specific spatial wavebands. We tested whether different receptive field properties of neurons in V1 scale with preferred spatial wavelength. Specifically, we investigated the size of the area that enhances responses, i.e., the grating summation field, the size of the inhibitory surround, and the distance dependence of signal coupling, i.e., the linking field.</p> <p>Results</p> <p>We found that the sizes of both grating summation field and inhibitory surround increase with preferred spatial wavelength. For the summation field this increase, however, is not strictly linear. No evidence was found that size of the linking field depends on preferred spatial wavelength.</p> <p>Conclusion</p> <p>Our data show that some receptive field properties are related to preferred spatial wavelength. This speaks in favor of the hypothesis that processing in V1 supports scale-invariant aspects of visual performance. However, not all properties of receptive fields in V1 scale with preferred spatial wavelength. Spatial-wavelength independence of the linking field implies a constant spatial range of signal coupling between neurons with different preferred spatial wavelengths. This might be important for encoding extended broad-band visual features such as edges.</p

Real-Time, Transcranial Monitoring of Safe Blood-Brain Barrier Opening in Non-Human Primates

The delivery of drugs to specific neural targets faces two fundamental problems: (1) most drugs do not cross the blood-brain barrier, and (2) those that do, spread to the entire brain. To date, there exists only one non-invasive methodology with the potential to solve these problems: selective blood-brain barrier (BBB) opening using micro-bubble enhanced focused ultrasound. We have recently developed a single-element 500-kHz spherical transducer ultrasound setup for targeted BBB opening in the non-human primate that does not require simultaneous MRI monitoring. So far, however, the targeting accuracy that can be achieved with this system has not been quantified systematically. In this paper, the accuracy of this system was tested by targeting caudate nucleus and putamen of the basal ganglia in two macaque monkeys. The average lateral targeting error of the system was ∼2.5 mm while the axial targeting error, i.e., along the ultrasound path, was ∼1.5 mm. We have also developed a real-time treatment monitoring technique based on cavitation spectral analysis. This technique also allowed for delineation of a safe and reliable acoustic parameter window for BBB opening. In summary, the targeting accuracy of the system was deemed to be suitable to reliably open the BBB in specific sub-structures of the basal ganglia even in the absence of MRI-based verification of opening volume and position. This establishes the method and the system as a potentially highly useful tool for brain drug delivery

Long-Term Safety of Repeated Blood-Brain Barrier Opening via Focused Ultrasound with Microbubbles in Non-Human Primates Performing a Cognitive Task

Focused Ultrasound (FUS) coupled with intravenous administration of microbubbles (MB) is a non-invasive technique that has been shown to reliably open (increase the permeability of) the blood-brain barrier (BBB) in multiple in vivo models including non-human primates (NHP). This procedure has shown promise for clinical and basic science applications, yet the safety and potential neurological effects of long term application in NHP requires further investigation under parameters shown to be efficacious in that species (500kHz, 200–400 kPa, 4–5μm MB, 2 minute sonication). In this study, we repeatedly opened the BBB in the caudate and putamen regions of the basal ganglia of 4 NHP using FUS with systemically-administered MB over 4–20 months. We assessed the safety of the FUS with MB procedure using MRI to detect edema or hemorrhaging in the brain. Contrast enhanced T1-weighted MRI sequences showed a 98% success rate for openings in the targeted regions. T2-weighted and SWI sequences indicated a lack edema in the majority of the cases. We investigated potential neurological effects of the FUS with MB procedure through quantitative cognitive testing of’ visual, cognitive, motivational, and motor function using a random dot motion task with reward magnitude bias presented on a touchpanel display. Reaction times during the task significantly increased on the day of the FUS with MB procedure. This increase returned to baseline within 4–5 days after the procedure. Visual motion discrimination thresholds were unaffected. Our results indicate FUS with MB can be a safe method for repeated opening of the BBB at the basal ganglia in NHP for up to 20 months without any long-term negative physiological or neurological effects with the parameters used

SERIES: eHealth in primary care. Part 1: Concepts, conditions and challenges.

Primary care is challenged to provide high quality, accessible and affordable care for an increasingly ageing, complex, and multimorbid population. To counter these challenges, primary care professionals need to take up new and innovative practices, including eHealth. eHealth applications hold the promise to overcome some difficulties encountered in the care of people with complex medical and social needs in primary care. However, many unanswered questions regarding (cost) effectiveness, integration with healthcare, and acceptability to patients, caregivers, and professionals remain to be elucidated. What conditions need to be met? What challenges need to be overcome? What downsides must be dealt with? This first paper in a series on eHealth in primary care introduces basic concepts and examines opportunities for the uptake of eHealth in primary care. We illustrate that although the potential of eHealth in primary care is high, several conditions need to be met to ensure that safe and high-quality eHealth is developed for and implemented in primary care. eHealth research needs to be optimized; ensuring evidence-based eHealth is available. Blended care, i.e. combining face-to-face care with remote options, personalized to the individual patient should be considered. Stakeholders need to be involved in the development and implementation of eHealth via co-creation processes, and design should be mindful of vulnerable groups and eHealth illiteracy. Furthermore, a global perspective on eHealth should be adopted, and eHealth ethics, patients' safety and privacy considered.Published versio

Begleitevaluation der arbeitsmarktpolitischen Integrationsmaßnahmen für Geflüchtete: Schlussbericht

Dieser Schlussbericht präsentiert wissenschaftliche Erkenntnisse über Umsetzung, Inanspruchnahme, Wirkungen und Wirtschaftlichkeit der arbeitsmarktpolitischen Integrationsmaßnahmen für Geflüchtete. Es werden die Fragen beantwortet, wie effektiv und effizient die zentralen Maßnahmen der Arbeitsförderung in den Rechtskreisen SGB II und SGB III für Personen im Kontext von Fluchtmigration im Hinblick auf ihre Arbeitsmarktintegration und soziale Teilhabe sind, und welche Faktoren, wie etwa Sprachförderung und individuelle und lokale Kontextfaktoren, die Maßnahmenwirksamkeit verstärken oder hemmen. Die kausalanalytisch angelegte Auswertung administrativer Daten wird durch die Untersuchung von Befragungsdaten und eine umfassende Implementationsanalyse ergänzt. Aus den empirischen Erkenntnissen abgeleitete Handlungsempfehlungen geben schließlich Impulse, um die Organisation, Prozesse und Rahmenbedingungen der arbeitsmarktpolitischen Integrationsmaßnahmen für Geflüchtete so zu gestalten, dass ihre positiven Wirkungen weiter verstärkt werden können.This final report presents findings on the implementation, utilization, effects and economic efficiency of labor market integration measures for refugees. It answers the questions of how effective and efficient the central employment measures of SGB II and SGB III are for refugee migrants with regard to their labor market integration and social participation, and which factors, such as language support and individual and local context factors, strengthen or inhibit the effectiveness of the measures. The causal analysis of administrative data is complemented by the examination of survey data and a comprehensive implementation analysis. Finally, policy recommendations derived from the empirical findings provide impulses for designing the organization, processes and framework conditions of labor market integration measures for refugees in such a way that their positive effects can be further enhanced

Noninvasive, Transient and Selective Blood-Brain Barrier Opening in Non-Human Primates In Vivo

The blood-brain barrier (BBB) is a specialized vascular system that impedes entry of all large and the vast majority of small molecules including the most potent central nervous system (CNS) disease therapeutic agents from entering from the lumen into the brain parenchyma. Microbubble-enhanced, focused ultrasound (ME-FUS) has been previously shown to disrupt noninvasively, selectively, and transiently the BBB in small animals in vivo. For the first time, the feasibility of transcranial ME-FUS BBB opening in non-human primates is demonstrated with subsequent BBB recovery. Sonications were combined with two different types of microbubbles (customized 4–5 µm and Definity®). 3T MRI was used to confirm the BBB disruption and to assess brain damage

Humans optimize decision-making by delaying decision onset.

Why do humans make errors on seemingly trivial perceptual decisions? It has been shown that such errors occur in part because the decision process (evidence accumulation) is initiated before selective attention has isolated the relevant sensory information from salient distractors. Nevertheless, it is typically assumed that subjects increase accuracy by prolonging the decision process rather than delaying decision onset. To date it has not been tested whether humans can strategically delay decision onset to increase response accuracy. To address this question we measured the time course of selective attention in a motion interference task using a novel variant of the response signal paradigm. Based on these measurements we estimated time-dependent drift rate and showed that subjects should in principle be able trade speed for accuracy very effectively by delaying decision onset. Using the time-dependent estimate of drift rate we show that subjects indeed delay decision onset in addition to raising response threshold when asked to stress accuracy over speed in a free reaction version of the same motion-interference task. These findings show that decision onset is a critical aspect of the decision process that can be adjusted to effectively improve decision accuracy