Representation of numerosity in posterior parietal cortex

Humans and animals appear to share a similar representation of number as an analog magnitude on an internal, subjective scale. Neurological and neurophysiological data suggest that posterior parietal cortex (PPC) is a critical component of the circuits that form the basis of numerical abilities in humans. Patients with parietal lesions are impaired in their ability to access the deep meaning of numbers. Acalculiac patients with inferior parietal damage often have difficulty performing arithmetic (2 + 4?) or number bisection (what is between 3 and 5?) tasks, but are able to recite multiplication tables and read or write numerals. Functional imaging studies of neurologically intact humans performing subtraction, number comparison, and non-verbal magnitude comparison tasks show activity in areas within the intraparietal sulcus (IPS). Taken together, clinical cases and imaging studies support a critical role for parietal cortex in the mental manipulation of numerical quantities. Further, responses of single PPC neurons in non-human primates are sensitive to the numerosity of visual stimuli independent of low-level stimulus qualities. When monkeys are trained to make explicit judgments about the numerical value of such stimuli, PPC neurons encode their cardinal numerical value; without such training PPC neurons appear to encode numerical magnitude in an analog fashion. Here we suggest that the spatial and integrative properties of PPC neurons contribute to their critical role in numerical cognition

Monotonic Coding of Numerosity in Macaque Lateral Intraparietal Area

As any child knows, the first step in counting is summing up individual elements, yet the brain mechanisms responsible for this process remain obscure. Here we show, for the first time, that a population of neurons in the lateral intraparietal area of monkeys encodes the total number of elements within their classical receptive fields in a graded fashion, across a wide range of numerical values (2–32). Moreover, modulation of neuronal activity by visual quantity developed rapidly, within 100 ms of stimulus onset, and was independent of attention, reward expectations, or stimulus attributes such as size, density, or color. The responses of these neurons resemble the outputs of “accumulator neurons” postulated in computational models of number processing. Numerical accumulator neurons may provide inputs to neurons encoding specific cardinal values, such as “4,” that have been described in previous work. Our findings may explain the frequent association of visuospatial and numerical deficits following damage to parietal cortex in humans

Navigating ‘taxation’ on the Congo River: the interplay of legitimation and ‘officialisation’

Based on comprehensive research among boat operators and navy personnel working on the Congo River (DRC), this article explores how assessments of ‘taxation’ are shaped by the interplay of legitimation and ‘officialisation’. As such, it draws upon and contributes to scholarly debates on taxpayers’ attitudes towards taxation. While boat operators resent having to pay a plethora of authorities, including the navy, along the Congo River, the article demonstrates how they locate these ‘taxes’ on a spectrum from more to less legitimate. These assessments are shaped by various factors: authorities’ legitimacy as ‘measured’ by their official mandate and importance; public and non-official service provision; and the deployment of symbols of ‘stateness’. In interaction, these factors legitimise and ‘officialise’ ‘taxes’ by the navy that are prohibited in legislation. These findings caution against the a priori use of the labels ‘official’ and ‘non-official’, emphasising the need to better grasp these notions’ emic understandings

Gated communities: Definitions, causes and consequences

Gated communities became an 'object of study' in the 1990s as social scientists observed their growth in several cities; they are now a feature of the urban landscape in most cities around the world. The expansion of gated communities has led to prolific research, examining different aspects of this type of residential development and providing evidence from case studies worldwide. This paper reviews how gated communities are conceptualised according to the literature and identifies the main factors influencing their development. It also considers spatial, economic, political and social consequences of the development of gated communities. These elements should be taken into account by planners and policymakers to minimise their negative impacts and maximise the positive consequences of a residential option that is likely to be part of the urban landscape for a long time

Individual and non‐additive effects of exotic sap‐feeders on root functional and mycorrhizal traits of a shared conifer host

Forest pests drive tree mortality through disruption of functional traits linked to nutrient acquisition, growth and reproduction. The impacts of attack by individual or multiple above‐ground herbivores on root functional traits critical to tree health have received little attention. This is especially true for exotic herbivores, organisms often found in disturbed forests. We excavated whole‐root systems from eastern hemlock (Tsuga canadensis) individuals experimentally infested with hemlock woolly adelgid (HWA: Adelges tsugae) and elongate hemlock scale (EHS: Fiorina externa) individually, or in combination, for periods of 2 and 4 years. Below‐ground root biomass, functional traits and storage nutrients were measured to assess impacts of herbivory. We also quantified ectomycorrhizal fungal (EMF) colonisation of fine roots and used culture‐independent methods to examine EMF diversity. Trees infested with HWA had a greater root mass fraction (root to total biomass ratio), although feeding had no observable effects on root functional traits (e.g. specific root length) or on resource allocation to roots. HWA feeding did significantly reduce EMF colonisation of hemlock fine roots, though surprisingly, EMF diversity and that of other fungal associates were unaffected. In contrast to HWA, EHS (alone or in conjunction with HWA) feeding had no observable effect on below‐ground traits or EMF colonisation alone; however, its presence mediated HWA effects when trees were co‐infested. Simultaneous infestation within the same year yielded significant reductions in EMF colonisation, whereas prior EHS attack weakened HWA effects. Our results collectively suggest that prior EHS attack dampens the impact of HWA on below‐ground functional traits. This highlights how the timing and sequence of herbivore arrival can alter plant‐mediated interactions between herbivores and their effects on above–below‐ground linkages and associated tree health

Expression of CXCL10 is associated with response to radiotherapy and overall survival in squamous cell carcinoma of the tongue

Five-year survival for patients with oral cancer has been disappointingly stable during the last decades, creating a demand for new biomarkers and treatment targets. Lately, much focus has been set on immunomodulation as a possible treatment or an adjuvant increasing sensitivity to conventional treatments. The objective of this study was to evaluate the prognostic importance of response to radiotherapy in tongue carcinoma patients as well as the expression of the CXC-chemokines in correlation to radiation response in the same group of tumours. Thirty-eight patients with tongue carcinoma that had received radiotherapy followed by surgery were included. The prognostic impact of pathological response to radiotherapy, N-status, T-stage, age and gender was evaluated using Cox's regression models, Kaplan-Meier survival curves and chi-square test. The expression of 23 CXC-chemokine ligands and their receptors were evaluated in all patients using microarray and qPCR and correlated with response to treatment using logistic regression. Pathological response to radiotherapy was independently associated to overall survival with a 2-year survival probability of 81 % for patients showing a complete pathological response, while patients with a non-complete response only had a probability of 42 % to survive for 2 years (p = 0.016). The expression of one CXC-chemokine, CXCL10, was significantly associated with response to radiotherapy and the group of patients with the highest CXCL10 expression responded, especially poorly (p = 0.01). CXCL10 is a potential marker for response to radiotherapy and overall survival in patients with squamous cell carcinoma of the tongue