Delayed-matching-to-position working memory in mice relies on NMDA-receptors in prefrontal pyramidal cells

A hypofunction of N-methyl-D-aspartate glutamate receptors (NMDARs) has been implicated in the pathogenesis of schizophrenia by clinical and rodent studies. However, to what extent NMDAR-hypofunction in distinct cell-types across the brain causes different symptoms of this disease is largely unknown. One pharmaco-resistant core symptom of schizophrenia is impaired working memory (WM). NMDARs have been suggested to mediate sustained firing in excitatory neurons of the prefrontal cortex (PFC) that might underlie WM storage. However, if NMDAR-hypofunction in prefrontal excitatory neurons may indeed entail WM impairments is unknown. We here investigated this question in mice, in which NMDARs were genetically-ablated in PFC excitatory cells. This cell type-selective NMDAR-hypofunction caused a specific deficit in a delayed-matching-to-position (DMTP) 5-choice-based operant WM task. In contrast, T-maze rewarded alternation and several psychological functions including attention, spatial short-term habituation, novelty-processing, motivation, sociability, impulsivity, and hedonic valuation remained unimpaired at the level of GluN1-hypofunction caused by our manipulation. Our data suggest that a hypofunction of NMDARs in prefrontal excitatory neurons may indeed cause WM impairments, but are possibly not accounting for most other deficits in schizophrenia.

Hedonic valuation of apartments in Kenya

PurposeThis paper applies the hedonic pricing model (HPM) approach to identify critical determinants of apartment value and employs the technique to develop a valuation model that can accurately estimate the value of apartments.Design/methodology/approachThe research employed a case study design that was limited to transaction sales and attribute data of apartments in Nyali estate, Mombasa County in Kenya. A sample of 120 sales of apartments obtained from registered real estate firms was analyzed using quantitative methods.FindingsAccording to the study results, the hedonic valuation model developed comprises four critical determinants of apartment value, namely, number of parking lots, presence of swimming pool, age of apartment and provision of balcony. The hedonic model was tested and found to be accurate and reliable in estimating apartment value.Research limitations/implicationsThe model will improve accuracy, reliability and efficiency in valuation. The application of the model in the valuation of apartments is, however, limited to the case study area where the data are obtained. The scope of application of the model may be improved by increasing the sample size to include apartment sales data from other estates in Mombasa County.Originality/valuePrevious studies that have used the HPM technique in analysis of apartment values have focused on the “explanatory” and “contributory” power of attributes on apartment values, rather than the development and use of the model to measure value. The present study is the first to develop a HPM equation for property value estimation in the apartment real estate sector in Kenya.

A Farewell to Art: Aesthetics as a Topic in Psychology and Neuroscience

Empirical aesthetics and neuroaesthetics study two main issues: the valuation of sensory objects and art experience. These two issues are often treated as if they were intrinsically interrelated: Research on art experience focuses on how art elicits aesthetic pleasure, and research on valuation focuses on special categories of objects or emotional processes that determine the aesthetic experience. This entanglement hampers progress in empirical aesthetics and neuroaesthetics and limits their relevance to other domains of psychology and neuroscience. Substantial progress in these fields is possible only if research on aesthetics is disentangled from research on art. We define aesthetics as the study of how and why sensory stimuli acquire hedonic value. Under this definition, aesthetics becomes a fundamental topic for psychology and neuroscience because it links hedonics (the study of what hedonic valuation is in itself) and neuroeconomics (the study of how hedonic values are integrated into decision making and behavioral control). We also propose that this definition of aesthetics leads to concrete empirical questions, such as how perceptual information comes to engage value signals in the reward circuit or why different psychological and neurobiological factors elicit different appreciation events for identical sensory objects.

The brain’s hedonic valuation system’s resting-state connectivity predicts weight loss and correlates with leptin

Weight gain is often associated with the pleasure of eating foods rich in calories and lack of willpower to reduce such food cravings, but empirical evidence is sparse. Here we investigated the role that connectivity within the brain’s hedonic valuation system (BVS, the ventral striatum and the ventromedial prefrontal cortex) at rest plays (1) to predict weight gain or loss over time and (2) for homeostatic hormone regulation. We found that intrinsic connectivity within the BVS at rest (RSC) predicted out-of-sample weight changes over time in lean and obese participants. Counterintuitively, such BVS RSC was higher in lean versus obese participants before the obese participants underwent a drastic weight loss intervention (Roux-en-Y gastric bypass surgery, RYGB). The RYGB surgery increased BVS RSC in the obese after surgery. The obese participants’ increase in BVS RSC correlated with decreases in fasting state systemic leptin, a homeostatic hormone signalling satiety that has been previously linked to dopamine functioning. Taken together, our results indicate a first link between brain connectivity in reward circuits in a more tonic state at rest, homeostatic hormone regulation involved in dopamine functioning and ability to lose weight.Significance statementWith obesity rates on the rise, advancing our understanding of what factors drive people’s ability to lose and gain weight is crucial. This research is the first to link what we know about the brain’s hedonic valuation system (BVS) to weight loss and homeostatic hormone regulation. We found that connectivity at rest (RSC) within the BVS system predicted changes in weight, differentiated between lean and obese participants, and increased after a weight loss intervention (gastric bypass surgery). Interestingly, the extent to which BVS RSC improved after surgery correlated to decreases in circulating levels of the satiety hormone leptin. These findings are the first to reveal the neural and hormonal determinants of weight loss, combining hedonic and homeostatic drivers of (over-)eating.

A hedonic valuation of sanitation services in Guatemala

Many developing countries lack universal sanitation services for residents. Years of inappropriate disposal of solid waste and wastewater have increased the potential for devastating environmental and health issues. An economic valuation of sanitation services may help in planning investment projects by demonstrating the benefits that households derive from having access to improved sanitation. We examine Guatemala as a case study and employ a series of hedonic models to estimate the value that households in Guatemala assign to the sanitation services of solid waste collection and connections to sewer infrastructure. Findings indicate that residents are willing to pay higher rents for both wastewater and solid waste removal. Policy implications are discussed.

The Neurobiology of Sensory Valuation

This chapter introduces the reader to the basic features of the neurobiological system involved in forming a hedonic liking response for sensory objects. In this way it aims to provide nonneuroscientists working in empirical aesthetics with a first primer on the neurobiological mechanisms and computational principles that underlie aesthetic appreciation. It describes how hedonic valuation is primarily computed by neural processes in the mesocorticolimbic reward circuit, and reviews some of the intrinsic and extrinsic factors that modulate these processes, thereby influencing how likable or dislikable a stimulus is experienced to be. It is argued that the neuroscientific evidence presented here suggests that the computational principles driving aesthetic appreciation can only be understood if seen as fundamentally rooted in functional mechanisms that evolved to help regulate adaptive behavior.