Absence of spatial tuning in the orbitofrontal cortex.

There is limited data in the literature to explicitly support the notion that neurons in OFC are truly action-independent in their coding. We set out to specifically test the hypothesis that OFC value-related neurons in area 13 m of the monkey do not carry information about the action required to obtain that reward--that activity in this area represents reward values in an abstract and action-independent manner. To accomplish that goal we had two monkeys select and execute saccadic eye movements to 81 locations in the visual field for three different kinds of juice rewards. Our detailed analysis of the response fields indicates that these neurons are insensitive to the amplitude or direction of the saccade required to obtain these rewards. Our data thus validate earlier proposals that neurons of 13 m in the OFC encode subjective value independent of the saccadic action required to obtain that reward

Model Fits to Data.

<p>Using the scale from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0112750#pone-0112750-g004" target="_blank">figure 4</a>, which scales by the average firing rate for each stimulus location, these are heat maps across the visual field of the model fits for example neurons from subject 1 and subject 2 during the (A) early period of analysis and the (B) late period of analysis.</p

Plane Fitted Slopes.

<p>Histogram plots of the slopes of the plane along the x and y axis during the early and late analysis using the linear model. White bars represent Subject 1 and black bars represent Subject 2 with grey representing the linear fits that create a plane statistically different from zero. The statistically significant linear fits do not support the conclusions that there is separate group of neurons for the early analysis (<b>c</b>²(1,84) = 55.05, p<0.001) or the late analysis (<b>c</b>²(1,84) = 65.19, p<0.001).</p

Example neurons from each subject.

<p>Each graph plots spikes per second as a function of time in milliseconds and each line represents the average spike rate of the neuron when the subject was presented with one of three rewards. (A) For this particularly neuron the firing rates following stimulus presentation are statistically different (ANOVA, F(2,652) = 3.63, p = 0.0271), while the firing rates following the receipt of reward are not statistically different (ANOVA, F(2,652) = 1.67, p = 0.1889). (B) The example neuron for Subject 2 has statistically different responses to the presentation of the reward stimuli (ANOVA, F(2,551) = 4.11, p = 0.017) and the neurons responds statistically differently to the rewards (ANOVA, (2,551) = 10.96, p<0.001.</p

MR Image.

<p>Subject 1's MRI image depicts the center of the recording chamber. For reference, a transparent image of a macaque brain atlas reveals the target as Walker's area 13 M.</p

AIC Differences.

<p>Histograms of the difference in the AIC; white represents Subject 1 and black represents Subject 2 during the early analysis and late analysis. The lower axis is constructed by taking the AIC number for a uniform firing rate and subtracting the AIC number for the (A) hemifield, (B) linear, and (C) gaussian models. Neurons to the left of zero are better fit by the ‘mean’ model. For Subject 1, the binomial probabilities of observing so many negative AIC differences if the models fit equally well are all less that 0.05 (early analysis hemifield: p = 0.0336, late analysis hemifield: p = 0.006, early analysis linear: p = 0.0014, late analysis linear: p = 0.0349, early analysis gaussian: p = 0.0001, late analysis gaussian: p = 0.0001). For Subject 2, the binomial probabilities of observing so many negative AIC differences by chance are at or below 0.055 (early analysis hemifield: p<0.0001 late analysis hemifield: p<0.00005 early analysis linear: p = 0.055, late analysis linear: p = 0.055 early analysis gaussian: p<0.00005, late analysis gaussian: p = 0.0087).</p

Binomial probabilities 7 time points across the trial.

<p>Binomial probabilities are calculated as the probability (p = 0.5) of finding k = number of negative AIC differences given the total number of neurons (n) for Subject 1 (a and b) and Subject 2 (c and d). The sliding windows are aligned to the target onset (a and c) and the reward onset (b and d). On each of the graphs the blue, red, and green lines represent the binomial probabilities for the difference between the gaussian, hemifield, and linear models, respectively, and the mean.</p

Transitive Behavior.

<p>(A) Representative day of choices made during free choice trials: Subject 1 performed a total of 70 free choice trials during one recording session. Plotted are histograms representing the probability the subject chose the preferred juice flavor (berry or orange) given the juice pairing ({berry, orange},{orange, grape},{berry, grape}). During the representative session, the subject chose berry juice over orange juice consistently (n = 26), orange of grape juice with a probability of 0.83 (n = 21), and berry juice over grape just consistently (n = 23). During this session the subject exhibited transitive behavior with berry<b>≥</b>orange<b>≥</b>grape. (B) Across the 48 recording sessions used in the neural analysis for Subject 1. The subject's preferences remained consistent. The subject chose berry juice over orange juice (m = 0.8405, se = 0.0265), orange juice over grape juice (m = 0.8504, se = 0.0287), and berry juice over grape juice (m = 0.899, se = 0.0201). The monkey's behavior exhibits robust transitivity and consistent preferences indicating that the subject assigned value to the stimuli representative of the three juice flavors. (C) Analysis across the 36 recording sessions used in the neural analysis of Subject 2. The subject's preferences remained consistent. The subject chose apple juice over grape juice (m = 0.99 s.e. = 0.0042), grape juice over water (m = 0.8387, se = 0.0282), and apple juice over water (m = 0.9830, se = 0.0110). The monkey's behavior exhibits robust transitivity indicating that he has learned the associative value of the stimuli.</p

The psychosocial impact of childhood dementia on children and their parents: a systematic review

Abstract Background Childhood dementias are a group of rare and ultra-rare paediatric conditions clinically characterised by enduring global decline in central nervous system function, associated with a progressive loss of developmentally acquired skills, quality of life and shortened life expectancy. Traditional research, service development and advocacy efforts have been fragmented due to a focus on individual disorders, or groups classified by specific mechanisms or molecular pathogenesis. There are significant knowledge and clinician skill gaps regarding the shared psychosocial impacts of childhood dementia conditions. This systematic review integrates the existing international evidence of the collective psychosocial experiences of parents of children living with dementia. Methods We used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We systematically searched four databases to identify original, peer-reviewed research reporting on the psychosocial impacts of childhood dementia, from the parent perspective. We synthesised the data into three thematic categories: parents’ healthcare experiences, psychosocial impacts, and information and support needs. Results Nineteen articles met review criteria, representing 1856 parents. Parents highlighted extensive difficulties connecting with an engaged clinical team and navigating their child’s rare, life-limiting, and progressive condition. Psychosocial challenges were manifold and encompassed physical, economic, social, emotional and psychological implications. Access to coordinated healthcare and community-based psychosocial supports was associated with improved parent coping, psychological resilience and reduced psychological isolation. Analysis identified a critical need to prioritize access to integrated family-centred psychosocial supports throughout distinct stages of their child’s condition trajectory. Conclusion This review will encourage and guide the development of evidence-based and integrated psychosocial resources to optimise quality of life outcomes for of children with dementia and their families

From Womb to Neighborhood: A Racial Analysis of Social Determinants of Psychosis in the United States.

The authors examine U.S.-based evidence that connects characteristics of the social environment with outcomes across the psychosis continuum, from psychotic experiences to schizophrenia. The notion that inequitable social and economic systems of society significantly influence psychosis risk through proxies, such as racial minority and immigrant statuses, has been studied more extensively in European countries. While there are existing international reviews of social determinants of psychosis, none to the authors' knowledge focus on factors in the U.S. context specifically-an omission that leaves domestic treatment development and prevention efforts incomplete and underinformed. In this review, the authors first describe how a legacy of structural racism in the United States has shaped the social gradient, highlighting consequential racial inequities in environmental conditions. The authors offer a hypothesized model linking structural racism with psychosis risk through interwoven intermediary factors based on existing theoretical models and a review of the literature. Neighborhood factors, cumulative trauma and stress, and prenatal and perinatal complications were three key areas selected for review because they reflect social and environmental conditions that may affect psychosis risk through a common pathway shaped by structural racism. The authors describe evidence showing that Black and Latino people in the United States suffer disproportionately from risk factors within these three key areas, in large part as a result of racial discrimination and social disadvantage. This broad focus on individual and community factors is intended to provide a consolidated space to review this growing body of research and to guide continued inquiries into social determinants of psychosis in U.S. contexts