bluuebunny/crossref_metadata_2025 huggingface dataset:
Obesity — a genetic disease of adipose tissue?
Authors: Arner Peter
Published: March 2008

Although the rapid increase in the prevalence of obesity in many countries suggests that environmental factors (mainly overeating and physical inactivity) play the most important role in the development of overweight, it is very likely that genetic factors also contribute. It appears that one major gene in combination with one or several minor genes constitute the genetic components behind excess accumulation of body fat in most obese individuals. However, monogenic obesity has been described in a few families due to changes in leptin, leptin receptor, prohormone convertase, pro-opiomelanocortin or melanocortin-4 receptor. None of the monogenic variants is of great importance for common human obesity; the latter genes are unknown so far. Results from genomic scans suggest that major obesity genes are located on chromosomes 2, 10, 11 and 20. Studies of candidate genes indicate that the minor obesity genes control important functions of adipose tissue, and that structural variance in these genes may alter adipose tissue function in a way that promotes obesity. Such genes are β2- and β3-adrenoceptors, hormone-sensitive lipase, tumour necrosis factor alpha, uncoupling protein-1, low-density lipoprotein receptor, and peroxisome proliferator activator receptor gamma-2. Some of these genes may promote obesity by gene–gene interactions (for example β3-adrenoceptors and uncoupling protein-1) or gene–environment interactions (for example β2-adrenoceptors and physical activity). Some are important for obesity only among women (for example β2- and β3-adrenoceptors, low-density lipoprotein receptor and tumour necrosis factor alpha). Few ‘non-adipose’ genes have so far shown a firm association to common human obesity, which could suggest that the important genes for the development of excess body fat also control adipose tissue function.
The role of dietary fat in body fatness: evidence from a preliminary meta-analysis of ad libitum low-fat dietary intervention studies
Authors: Astrup Arne , Ryan Louise , Grunwald Gary K. , Storgaard Mette , Saris Wim , Melanson Ed , Hill James O.
Published: March 2008

The role of high-fat diets in weight gain and obesity has been questioned because of inconsistent reports in the literature concerning the efficacy ofad libitumlow-fat diets to reduce body weight. We conducted a meta-analysis of weight loss occurring onad libitumlow-fat diets in intervention trials, and analysed the relationship between initial body weight and weight loss. We selected controlled trials lasting more than 2 months comparingad libitumlow-fat diets with a control group consuming their habitual diet or a medium-fat dietad libitumpublished from 1966 to 1998. Data were included from 16 trials with a duration of 2–12 months, involving 1728 individuals. No trials on obese subjects fulfilled the inclusion criteria. The weighted difference in weight loss between intervention and control groups was 2.55 kg (95 % CI, 1.5–3.5;P< 0.0001). Weight loss was positively and independently related to pre-treatment body weight (r= 0.52,P< 0.05) and to reduction in the percentage of energy as fat (0.37 kg / %,P< 0.005) in unweighted analysis. Extrapolated to a BMI of about 30 kg/m2and assuming a 10 % reduction in dietary fat, the predicted weight loss would be 4.4 kg (95 % CI, 2.0 to -6.8 kg). Because weight loss was not the primary aim in 12 of the 16 studies, it is unlikely that voluntary energy restriction contributed to the weight loss. Although there is no evidence that a high intake of simple sugars contributes to passive overconsumption, carbohydrate foods with a low glycaemic index may be more satiating and exert more beneficial effects on insulin resistance and cardiovascular risk factors. Moreover, an increase in protein content up to 25 % of total energy may also contribute to reducing total energy intake. In conclusion, a low-fat diet, high in protein and fibre-rich carbohydrates, mainly from different vegetables, fruits and whole grains, is highly satiating for fewer calories than fatty foods. This diet composition provides good sources of vitamins, minerals, trace elements and fibre, and may have the most beneficial effect on blood lipids and blood-pressure levels. A reduction in dietary fat without restriction of total energy intake prevents weight gain in subjects of normal weight and produces a weight loss in overweight subjects, which is highly relevant for public health.
Polyunsaturated fatty acid regulation of gene transcription: a mechanism to improve energy balance and insulin resistance
Authors: Clarke Steven D.
Published: March 2008

This review addresses the hypothesis that polyunsaturated fatty acids (PUFA), particularly those of then-3 family, play essential roles in the maintenance of energy balance and glucose metabolism. The data discussed indicate that dietary PUFA function as fuel partitioners in that they direct glucose toward glycogen storage, and direct fatty acids away from triglyceride synthesis and assimilation and toward fatty acid oxidation. In addition, then-3 family of PUFA appear to have the unique ability to enhance thermogenesis and thereby reduce the efficiency of body fat deposition. PUFA exert their effects on lipid metabolism and thermogenesis by up-regulating the transcription of the mitochondrial uncoupling protein-3, and inducing genes encoding proteins involved in fatty acid oxidation (e.g. carnitine palmitoyltransferase and acyl-CoA oxidase) while simultaneously down-regulating the transcription of genes encoding proteins involved in lipid synthesis (e.g. fatty acid synthase). The potential transcriptional mechanism and the transcription factors affected by PUFA are discussed. Moreover, the data are interpreted in the context of the role that PUFA may play as dietary factors in the development of obesity and insulin resistance. Collectively the results of these studies suggest that the metabolic functions governed by PUFA should be considered as part of the criteria utilized in defining the dietary needs forn-6 andn-3 PUFA, and in establishing the optimum dietary ratio forn-6 :n-3 fatty acids.
Obesity and the metabolic syndrome: the San Antonio Heart Study
Authors: Haffner Steven M.
Published: March 2008

Obesity, especially visceral adiposity, is a major determinant of the development of type 2 diabetes. Both visceral adiposity and insulin resistance are strongly related to cardiovascular risk factors in diabetic and non-diabetic subjects. One of the areas where the correlation between visceral fat (upper body adiposity) and cardiovascular risk is most apparent is the prediabetic state. We have recently shown that only prediabetic subjects (those who later develop type 2 diabetes) who are insulin resistant and with upper body adiposity have increased triglycerides, decreased HDL cholesterol and high blood pressure.
Dietary fat and insulin action in humans
Authors: Vessby Bengt
Published: March 2008

A high intake of fat may increase the risk of obesity. Obesity, especially abdominal obesity, is an important determinant of the risk of developing insulin resistance and non-insulin-dependent diabetes mellitus. It is suggested that a high proportion of fat in the diet is associated with impaired insulin sensitivity and an increased risk of developing diabetes, independent of obesity and body fat localization, and that this risk may be influenced by the type of fatty acids in the diet. Cross-sectional studies show significant relationships between the serum lipid fatty acid composition, which at least partly mirrors the quality of the fatty acids in the diet, and insulin sensitivity. Insulin resistance, and disorders characterized by insulin resistance, are associated with a specific fatty acid pattern of the serum lipids with increased proportions of palmitic (16 : 0) and palmitoleic acids (16 : 1 n-7) and reduced levels of linoleic acid (18 : 2 n-6). The metabolism of linoleic acid seems to be disturbed with increased proportions of dihomo-gamma linolenic acid (20 : 3 n-6) and a reduced activity of the Δ5 desaturase, while the activities of the Δ9 and Δ6 desaturases appear to be increased. The skeletal muscle is the main determinant of insulin sensitivity. Several studies have shown that the fatty acid composition of the phosholipids of the skeletal muscle cell membranes is closely related to insulin sensitivity. An increased saturation of the membrane fatty acids and a reduced activity of Δ5 desaturase have been associated with insulin resistance. There are several possible mechanisms which could explain this relationship. The fatty acid composition of the lipids in serum and muscle is influenced by diet, but also by the degree of physical activity, genetic disposition, and possibly fetal undernutrition. However, controlled dietary intervention studies in humans investigating the effects of different types of fatty acids on insulin sensitivity have so far been negative.
Is long-term weight loss possible?
Authors: Lean Michael E. J.
Published: March 2008

Any intervention which causes negative energy balance is guaranteed to be efficacious in producing weight loss, which will continue while there is negative energy balance or be maintained as long as the new energy balance is maintained. In clinical practice compliance is rarely 100 % so the efficiency of even the most efficacious treatment is usually low. However, recent evidence-based guidelines have recognized the clinical benefits of moderate (5–10 %) weight loss, which is achievable using a variety of interventions. Long-term studies of ‘weight loss’ are, in reality, combinations of weight loss (usually completed in 1–6 months) followed by variable weight maintenance, set in the context of progressive adult weight gain in an obesogenic environment. Few studies have adopted specific and separate strategies for weight loss and weight maintenance. Meta-analyses conducted by non-expert methodologists have failed to recognize these distinctions, and have criticized the available research without understanding the different needs of studies with weight change as the outcome variable, which require randomized controlled trials (RCT), and those with weight loss as the treatment, intended to improve metabolic or biomedical outcome measures. An RCT design is inapplicable to studies of biomedical end points (e.g. cardiac risk factors) when weight loss is the treatment. Because fixed weight loss cannot be prescribed there is always a range of weight changes in any study, and single-sample studies with regression analysis provide the best design. An RCT study design does not give useful information about clinical value as the control group is always ‘treated’ to some extent. Placebo- (or control)-subtracted differences are misleading because in an RCT all subjects recruited to active treatment, including non-responders, are continued on treatment for the full duration of the study. In routine clinical practice, treatments are changed in the light of early experience as a therapeutic trial to optimize the results for each individual, and audit is required to evaluate ‘long term weight loss’.
The Finnish Diabetes Prevention Study
Authors: Uusitupa Matti , Louheranta Anne , Lindström Jaana , Valle Timo , Sundvall Jouko , Eriksson Johan , Tuomilehto Jaakko
Published: March 2008

The aim of the Finnish Diabetes Prevention Study is to assess the efficacy of an intensive diet–exercise programme in preventing or delaying type 2 diabetes in individuals with impaired glucose tolerance (IGT) and to evaluate the effect of the programme on the risk factors of atherosclerotic vascular diseases and the incidence of cardiovascular events. In this ongoing study, a total of 523 overweight subjects with IGT based on two oral glucose tolerance tests were randomized to either an intervention group or a control group. The main measure in the intervention group is individual dietary advice aimed at reducing weight and intake of saturated fat and increasing intake of dietary fibre. The intervention subjects are individually guided to increase their level of physical activity. The control group receives general information about the benefits of weight reduction, physical activity and healthy diet in the prevention of diabetes. A pilot study began in 1993, and recruitment ended in 1998. By the end of April 1999 there were 65 new cases of diabetes, 34 drop-outs and one death. The weight reduction was greater (-4.6 kg) at 1 year in the intervention group (n = 152) than in the control group (n = 143, -0.9 kg, P < 0.0001), and this difference was sustained in the second year of follow-up. At 1 year 43.4 % and at 2 years 41.8 % of the intervention subjects had achieved a weight reduction of at least 5 kg, while the corresponding figures for the control subjects were 14.0 and 12.0 % (P < 0.001 between the groups). At 1 year the intervention group showed significantly greater reductions in 2 h glucose, fasting and 2 h insulin, systolic and diastolic blood pressure, and serum triglycerides. Most of the beneficial changes in cardiovascular risk factors were sustained for 2 years. These interim results of the ongoing Finnish Diabetes Prevention Study demonstrate the efficacy and feasibility of the lifestyle intervention programme.
Low glycaemic-index foods
Authors: Björck Inger , Liljeberg Helena , Östman Elin
Published: March 2008

Accumulating data indicate that a diet characterized by low glycaemic-index (GI) foods not only improves certain metabolic ramifications of insulin resistance, but also reduces insulin resistance per se. Epidemiological data also suggest a protective role against development of non-insulin-dependent diabetes mellitus and cardiovascular disease. A major disadvantage in this connection is the shortage of low-GI foods, and many common starchy staple foods, such as bread products, breakfast cereals and potato products, have a high GI. Studies in our laboratory show that it is possible to significantly lower the GI of starchy foods, for example by choice of raw material and/or by optimizing the processing conditions. Such low-GI foods may or may not influence glucose tolerance at a subsequent meal. Consequently, certain low-GI breakfasts capable of maintaining a net increment in blood glucose and insulin at the time of the next meal significantly reduced post-prandial glycaemia and insulinaemia following a standardized lunch meal, whereas others had no ‘second-meal’ impact. These results imply that certain low-GI foods may be more efficient in modulating metabolism in the long term. Although the literature supports a linear correlation between the GI and insulinaemic index (II) of foods, this is not always the case. Consequently, milk products elicited elevated IIs, indistinguishable from a white bread reference meal, despite GIs in the lower range. This inconsistent behaviour of milk products has not been acknowledged, and potential metabolic consequences remain to be elucidated.
Dietary fibre, lente carbohydrates and the insulin-resistant diseases
Authors: Jenkins David J. A. , Axelsen Mette , Kendall Cyril W. C. , Augustin Livia S. A. , Vuksan Vladimir , Smith Ulf
Published: March 2008

Several epidemiological studies link consumption of fibre-rich foods to a reduced risk of type 2 diabetes and CHD. The ‘fibre hypothesis’ suggested that this was a direct effect of fibre. However, fibre-rich foods contain different types of fibre as well as other potentially beneficial compounds, and many foods naturally high in fibre have low glycaemic and insulinaemic indices, possibly due to food form. The question therefore emerges as to the effect of isolated fibreper seon insulin sensitivity, lipids and other risk factors associated with the metabolic syndrome. Many beneficial effects are seen with pharmacological doses of isolated viscous soluble fibre, including improved insulin sensitivity, decreased LDL-cholesterol levels and decreased clotting factors. Similar effects are seen with low glycaemic-index foods. In contrast, insoluble non-viscous cereal fibre is not seen to act directly on risk factors when taken in refined foods such as in milled flour. Since cereal fibre, the major type of fibre in western diets, does not directly act on the risk factors for the metabolic syndrome, the question remains as to possible mechanisms. Until now, fibre and the nature and processing of the starch and particle size have been seen as the main determinants of the metabolic response to starchy foods. However, fibre-rich foods also have an increased protein-to-carbohydrate ratio. Hence we suggest that the protective effect of fibre may also be due to increased vegetable protein content, which may act directly to reduce clotting factors and oxidized LDL-cholesterol levels.
Can dietary intervention produce long-term reductionin insulin resistance?
Authors: Mann Jim I.
Published: March 2008

Insulin sensitivity is potentially enhanced by a range of diet-related changes including reduction of visceral adiposity, a reduction in saturated fatty acids, and possibly a redistribution of the proportions of various unsaturated fatty acids. While there is evidence to suggest that lifestyle changes can reduce the risk of progression of impaired glucose tolerance to type 2 diabetes, there are no clinical trials which have conclusively demonstrated that any measure can reduce insulin resistance in the long term to an extent that can prevent the development of type 2 diabetes and other clinical complications. Evidence concerning the possibilities for reducing visceral adiposity and altering the nature of dietary fat are therefore considered. Attempts to achieve prolonged and substantial weight reduction in adults have not been encouraging, and it may be that preventing further weight gain is the most realistic target in this age group. In childhood the attempts have been more successful. The development of new approaches to achieving behavioural change and an environment which facilitates physical activity and appropriate food choices will be essential for more successful individual and population attempts to facilitate reduction in insulin resistance by weight loss. Changes in the nature of dietary fat appear to be more easily achieved. This is already a component of dietary advice aimed at cardiovascular risk reduction, and should be reinforced now with a view to also achieving a reduction in insulin resistance.
Strategies to prevent the metabolic syndrome at the population level: role of authorities and non-governmental bodies
Authors: Bruce Åke
Published: March 2008

The remarkable increase over the past 40 years in some chronic diseases, including the metabolic syndrome, has increased the demand for government and international policies to encourage various approaches to decrease the risk of these diseases. There are some prerequisites for working out successful national food and nutrition policies. Firstly, it is necessary to have a clear picture of the dietary pattern in a country and its associated public health problems. Based on these data, nutrient recommendations and goals are formulated by international or national scientific committees. Governments should translate these nutrient goals into food goals and eventually into national dietary guidelines. The means by which the national authorities can implement a nutrition policy include fortification and supplementation. Equally important are educational and informative tools, such as labelling on the packed food products including information about ingredients and nutrient content. With respect to the metabolic syndrome, this implies nutrient recommendations regarding the intake of fat and carbohydrates (energy per cent) and dietary fibre; dietary guidelines regarding balance between energy intake and expenditure; decreased consumption of products rich in fat and increased consumption of cereals and other products rich in dietary fibre, etc.; recommendations from the authorities regarding nutrient labelling (content of fat and dietary fibre) on relevant products; and nutrient and health claims and other aids (symbols) as tools to make it easier for consumers to select the appropriate food products.
Kleptocracy and Its Many Faces: The Challenges of Justiciability of the Right to Health Care in Nigeria
Authors: Nnamuchi Obiajulu
Published: March 2008

This article analyses the difficulties surrounding justiciability of the right to health care in Nigeria and the implications for access issues. It argues that claims denying justiciability on the grounds of the absence of a legal foundation and / or paucity of resources are misplaced. This reasoning derives from an interrogation of the rationale for and the consequences of the designation of what ought to be the right to health care as a Directive Principle, kleptocracy as an impediment to actualizing the right to health care, and the impact of the domestication of the African Charter on Human and Peoples' Rights. Projecting into the future, the article analyses the challenges that would confront courts in Nigeria grappling with the normative content of the right to health care, arguing that the difficulties are not insurmountable and that, given the seemingly intractable nature of the issues, the courts should adopt a proactive interpretive approach.
Addressing Human Rights Concerns Raised by Mandatory HIV Testing of Pregnant Women through the Protocol to the African Charter on the Rights of Women
Authors: Durojaye Ebenezer
Published: March 2008

This article considers the importance of preventing mother to child transmission of HIV in Africa. It argues, however, that any approach to achieving this aim must be consistent with respect for human rights. In particular, it argues that mandatory HIV testing of pregnant women violates their rights to autonomy, health and reproductive care, and non-discrimination, all guaranteed in the Protocol to the African Charter on the Rights of Women and other international and regional human rights instruments. It concludes by arguing that respect for women's human rights should form the fulcrum for any call for mandatory or routine HIV testing of pregnant women in Africa.
Corporate Social Responsibility, Multinational Corporations and the Law in Nigeria: Controlling Multinationals in Host States
Authors: Amao Olufemi O
Published: March 2008

There is a general perception that home jurisdictions in vulnerable areas are powerless when it comes to the control of multinational corporations. While this assertion is largely correct, this article argues that there cannot be effective control of multinational corporations (“MNCs”) at international, regional or private level without the corresponding development of an effective minimum institutional framework at the domestic level. This article examines the Nigerian legal framework for the regulation of MNCs with a view to underlining the weaknesses in the domestic forum, and also examines the prospects for enhancing the capacity of a domestic framework for the effective control of MNCs. The article argues that, while corporate social responsibility practice by MNCs is becoming well entrenched, this development cannot replace the need for effective host state regulation. The article focuses on company law and human rights law and suggests viable possibilities within the local context that may enhance the control of MNCs.
“We Want Anti-models”: John Berryman's Eliotic Inheritance
Authors: COOPER BRENDAN
Published: March 2008

In his study Modern Poetry after Modernism, James Longenbach criticizes the lingering critical perception of the postmodernist development in poetry as a “breakthrough” narrative that rebelled against the traditionalism and impersonality of Eliotic modernism. As he points out, postmodern poets in fact confronted Eliot via a series of intricate and ambivalent interactive processes that are not confinable within this “breakthrough” narrative. In this paper, I use Longenbach's argument as a starting point for a re-examination of Eliot's influence on the major poetry of one of his more apparently vocal opponents: John Berryman. Berryman's attitude towards Eliot was radically ambivalent, based on an idea that poetic predecessors must become “anti-models,” figures whom the contemporary poet can only incorporate through productive gestures of reaction against them. In the light of this idea, I show that in Berryman's major works, Homage to Mistress Bradstreet and The Dream Songs, Eliot exerts a far stronger and more significant influence than has hitherto been recognized. My discussion of Berryman's participation in a postwar “Eliotic inheritance” allows for readings of these two poets that are not dependent upon crude oppositions between the “impersonal” and the “personal”. And as a consequence it opens the way for richer and more nuanced readings of Berryman's work as well as for invigorating reassessments of Eliot's own verse and his influence on twentieth-century poetry.
Cult Fiction: “Good” and “Bad” Communities in the Contemporary American Novel
Authors: HUTCHINSON COLIN
Published: March 2008

This article examines the way in which three contemporary novelists have interpreted the proliferation of cults and other independent communities in the USA. Thomas Pynchon's Vineland is read as a critique of individualism that regrets the loss of collective identity and purpose. A subsequent reading of Katherine Dunn's Geek Love demonstrates the destructive consequences of individual submission that draws parallels between the dynamics of “cult” communities and mainstream society. This is developed further in a discussion of Don DeLillo's Mao II, which is represented as an attempt to reconcile libertarian and communitarian discourses, while remaining mindful of the dangers of both.
What Does It Mean to Be an American? The Dialectics of Self-Discovery in Baldwin's “Paris Essays” (1950–1961)
Authors: MILLER JAMES
Published: March 2008

This article looks at a number of James Baldwin's early essays. These include “Stranger in the Village” (1953), “A Question of Identity” (1954), “Encounter on the Seine: Black Meets Brown” (1950) and “The Discovery of What It Means to Be an American” (1959). In these essays Baldwin resolves the contradiction between his sense of himself as an individual and his racial identity by affirming both his American citizenship and his racial identity as a source of cultural strength and authority. He conceives of race in dialectical terms, with the African American as the dynamic agent in a process envisaged as leading to an overcoming of both whiteness and blackness in favour of a reformulated American nationalism.
Hearing aids and tinnitus therapy: a 25-year experience
Authors: Trotter M I , Donaldson I
Published: March 2008

Objectives:

(1) To assess the subjective tinnitus perception of patients with audiologically proven hearing loss presenting to a tinnitus clinic, both before and after hearing aid provision; (2) to investigate subjective tinnitus perception in patients with unilateral and bilateral hearing loss; and (3) to assess the impact on tinnitus perception, if any, of a digital hearing aid programme in patients provided with hearing aids.

Design:

Prospective data collection for patients attending a tinnitus clinic over a 25-year period (1980–2004).

Setting:

University teaching hospital otolaryngology department.

Participants:

A total of 2153 consecutive patients attending a consultant-delivered specialist tinnitus clinic.

Main outcomes measures:

A visual analogue scale was used to assess the degree of tinnitus perception improvement, if any, comparing before versus after unilateral or bilateral aiding (in those with audiometrically proven hearing loss). A further assessment compared the effect of digital hearing aid programme introduction on symptomatic tinnitus perception in patients provided with unilateral or bilateral aids.

Results:

A total of 1440 patients were given hearing aids (826 unilateral and 614 bilateral). There was little difference in tinnitus perception, comparing overall aiding results in unilaterally or bilaterally aided patients. Overall, 554 (67 per cent) of unilaterally aided patients and 424 (69 per cent) of bilaterally aided patients reported some improvement in their tinnitus perception following aiding. There was a statistically significant improvement in tinnitus perception, comparing analogue aids with digital hearing aids, following introduction of a digital hearing aid programme in 2000, in both unilaterally (p < 0.001) and bilaterally (p < 0.001) aided patients.

Conclusions:

Provision of hearing aids in patients with audiometrically demonstrable hearing loss can play a very important part in tinnitus control. The additional improvement in tinnitus control observed following introduction of programmable digital aids had a summative effect in the management of these patients.
Screening for gap junction protein beta-2 gene mutations in Malays with autosomal recessive, non-syndromic hearing loss, using denaturing high performance liquid chromatography
Authors: Aishah Z Siti , Khairi M D Mohd , Normastura A R , Zafarina Z , Zilfalil B A
Published: March 2008

Objective:

To determine the frequency and type of gap junction protein beta-2 gene mutations in Malay patients with autosomal recessive, non-syndromic hearing loss.

Methods:

A total of 33 Malay patients with autosomal recessive, non-syndromic hearing loss were screened for mutations in the Cx26 coding region. Deoxyribonucleic acid was extracted from buccal swab samples and subjected to polymerase chain reaction. Slow-reannealing was performed, followed by screening using denaturing high performance liquid chromatography.

Results:

Eight of the samples (24.2 per cent) showed heterozygous peaks, and further sequencing of these samples revealed four patients (50.0 per cent) with the W24X mutation, two (25.0 per cent) with the V37I mutation and another two (25.0 per cent) with the G4D mutation.

Conclusions:

Analysis of buccal swab samples by denaturing high performance liquid chromatography is noninvasive and suitable for rapid and reliable screening of gap junction protein beta-2 gene mutations in patients with autosomal recessive, non-syndromic hearing loss. Malay patients with autosomal recessive, non-syndromic hearing loss have different kinds of gap junction protein beta-2 gene mutations which are rarely found in other populations.
Why people see things that are not there: A novel Perception and Attention Deficit model for recurrent complex visual hallucinations
Authors: Collerton Daniel , Perry Elaine , McKeith Ian
Published: March 2008

As many as two million people in the United Kingdom repeatedly see people, animals, and objects that have no objective reality. Hallucinations on the border of sleep, dementing illnesses, delirium, eye disease, and schizophrenia account for 90% of these. The remainder have rarer disorders. We review existing models of recurrent complex visual hallucinations (RCVH) in the awake person, including cortical irritation, cortical hyperexcitability and cortical release, top-down activation, misperception, dream intrusion, and interactive models. We provide evidence that these can neither fully account for the phenomenology of RCVH, nor for variations in the frequency of RCVH in different disorders. We propose a novel Perception and Attention Deficit (PAD) model for RCVH. A combination of impaired attentional binding and poor sensory activation of a correct proto-object, in conjunction with a relatively intact scene representation, bias perception to allow the intrusion of a hallucinatory proto-object into a scene perception. Incorporation of this image into a context-specific hallucinatory scene representation accounts for repetitive hallucinations. We suggest that these impairments are underpinned by disturbances in a lateral frontal cortex–ventral visual stream system. We show how the frequency of RCVH in different diseases is related to the coexistence of attentional and visual perceptual impairments; how attentional and perceptual processes can account for their phenomenology; and that diseases and other states with high rates of RCVH have cholinergic dysfunction in both frontal cortex and the ventral visual stream. Several tests of the model are indicated, together with a number of treatment options that it generates.
“Economic man” in cross-cultural perspective: Behavioral experiments in 15 small-scale societies
Authors: Henrich Joseph , Boyd Robert , Bowles Samuel , Camerer Colin , Fehr Ernst , Gintis Herbert , McElreath Richard , Alvard Michael , Barr Abigail , Ensminger Jean , Henrich Natalie Smith , Hill Kim , Gil-White Francisco , Gurven Michael , Marlowe Frank W. , Patton John Q. , Tracer David
Published: March 2008

Researchers from across the social sciences have found consistent deviations from the predictions of the canonical model of self-interest in hundreds of experiments from around the world. This research, however, cannot determine whether the uniformity results from universal patterns of human behavior or from the limited cultural variation available among the university students used in virtually all prior experimental work. To address this, we undertook a cross-cultural study of behavior in ultimatum, public goods, and dictator games in a range of small-scale societies exhibiting a wide variety of economic and cultural conditions. We found, first, that the canonical model – based on self-interest – fails in all of the societies studied. Second, our data reveal substantially more behavioral variability across social groups than has been found in previous research. Third, group-level differences in economic organization and the structure of social interactions explain a substantial portion of the behavioral variation across societies: the higher the degree of market integration and the higher the payoffs to cooperation in everyday life, the greater the level of prosociality expressed in experimental games. Fourth, the available individual-level economic and demographic variables do not consistently explain game behavior, either within or across groups. Fifth, in many cases experimental play appears to reflect the common interactional patterns of everyday life.
Attentional deficit versus impaired reality testing: What is the role of executive dysfunction in complex visual hallucinations?
Authors: Behrendt Ralf-Peter
Published: March 2008

A “multifactorial” model should accommodate a psychological perspective, aiming to relate the phenomenology of complex visual hallucinations not only to neurobiological findings but also an understanding of the patient's psychological problems and situation in life. Greater attention needs to be paid to the role of the “lack of insight” patients may have into their hallucinations and its relationship to cognitive impairment.
A signal-detection-theory representation of normal and hallucinatory perception
Authors: Dolgov Igor , McBeath Michael K.
Published: March 2008

Collerton et al.'s Perception and Attention Deficit (PAD) model argues that all recurrent complex visual hallucinations (RCVH) result from maladaptive, deficient sensory and attentional processing. We outline a constructivist-based representation of perception using signal detection theory, in which hallucinations are modeled as false alarms when confirmational perceptual information is lacking. This representation allows for some individuals to have RCVH due to a criterion shift associated with attentional proficiency that results in an increased awareness of the environment.
Hallucinations and perceptual inference
Authors: Friston Karl J.
Published: March 2008

This commentary takes a closer look at how “constructive models of subjective perception,” referred to by Collerton et al. (sect. 2), might contribute to the Perception and Attention Deficit (PAD) model. It focuses on the neuronal mechanisms that could mediate hallucinations, or false inference – in particular, the role of cholinergic systems in encoding uncertainty in the context of hierarchical Bayesian models of perceptual inference (Friston 2002b; Yu & Dayan 2002).
The emergence of proto-objects in complex visual hallucinations
Authors: Halliday Glenda
Published: March 2008

There is little to refute in Collerton et al.'s argument that recurrent complex visual hallucinations involve multiple physiological mechanisms, and the target article's proposed PAD model implicitly incorporates this concept, advancing the field. The novel concept in this model is the intrusion of hallucinatory proto-objects into relatively preserved scenes. The weakness of the model is the lack of physiological detail for this mechanism.
Complex hallucinations in waking suggest mechanisms of dream construction
Authors: Pace-Schott Edward F.
Published: March 2008

Waking hallucinations suggest mechanisms of dream initiation and maintenance. Visual association cortex activation, yielding poorly attended-to, visually ambiguous dream environments, suggests conditions favoring hallucinosis. Attentional and visual systems, coactivated during sleep, may generate imagery that is inserted into virtual environments. Internally consistent dreaming may evolve from successive, contextually evoked images. Fluctuating arousal and context-evoked imagery may help explain dream features.
Born selfish? Rationality, altruism, and the initial state
Authors: Lucas Margery , Wagner Laura
Published: March 2008

Henrich et al. propose that humans are genetically equipped with learning mechanisms that enable them to acquire the preferences and beliefs related to economic prosocial behaviors. In addition to their cross-cultural data, they cite developmental evidence in support of this theory. We challenge Henrich et al.'s interpretation of the developmental data in a discussion of recent work which suggests that preferences for altruism and fairness may have an innate basis.
Visual hallucinations, attention, and neural circuitry: Perspectives from schizophrenia research
Authors: Spencer Kevin M. , McCarley Robert W.
Published: March 2008

We tested Collerton et al.'s model of visual hallucinations by re-examining a data set for correlations between visual hallucinations and measures of attentional function in schizophrenia patients. These data did not support their model. We suggest that cortical hyperexcitability plays an important role in hallucinations, and propose an alternative model that links evidence for cortical hyperexcitability with abnormal neural dynamics.
Sociality and self interest
Authors: Smith Vernon L.
Published: March 2008

Selfishness narrowly defined as choosing dominant outcomes independent of context is widely rejected by experimentalists. Humans live in two worlds of personal and impersonal exchange; both are manifestations of human sociality, but the emphasis on preferences rather than cultural norms of personal exchange across time too much reflects a limited economic modeling, and fails to capitalize on the fresher experimental economics message of culture and diversity.
Economic man: Self-interest and rational choice
Authors: Zizzo Daniel John
Published: March 2008

“Economic man” assumes not only self-interest, but also rationality of choices. The finding that ultimatum game offers can be explained by ambiguity aversion as well as pessimism, plus other findings, suggests the usefulness of taking bounded rationality more into account. Neurodevelopmental and heritability research supports the authors' emphasis on the importance of social learning and socialization.
Models of decision-making and the coevolution of social preferences
Authors: Henrich Joseph , Boyd Robert , Bowles Samuel , Camerer Colin , Fehr Ernst , Gintis Herbert , McElreath Richard , Alvard Michael , Barr Abigail , Ensminger Jean , Henrich Natalie Smith , Hill Kim , Gil-White Francisco , Gurven Michael , Marlowe Frank W. , Patton John Q. , Tracer David
Published: March 2008

We would like to thank the commentators for their generous comments, valuable insights and helpful suggestions. We begin this response by discussing the selfishness axiom and the importance of the preferences, beliefs, and constraints framework as a way of modeling some of the proximate influences on human behavior. Next, we broaden the discussion to ultimate-level (that is evolutionary) explanations, where we review and clarify gene-culture coevolutionary theory, and then tackle the possibility that evolutionary approaches that exclude culture might be sufficient to explain the data. Finally, we consider various methodological and epistemological concerns expressed by our commentators.
Response bias and aging on a recognition memory task
Authors: HUH TERRI J. , KRAMER JOEL H. , GAZZALEY ADAM , DELIS DEAN C.
Published: March 2008

Response bias reflects the decision rule an individual uses when faced
with uncertainty on recognition memory tasks. Recent studies indicate
frontal regions may mediate response bias performance. One theory of aging
also implicates frontal lobe contributions in age-related cognitive
changes. This suggests that frontal lobe changes may mediate response bias
in older adults. Consistent with this frontal aging hypothesis, we
predicted that response bias would become more liberal with age. Methods:
Participants were 181 younger (30–49) and 112 older normal adults
(75+) that were part of the California Verbal Learning Test-second edition
(CVLT-2) normative sample (total n = 1078). We used parametric
measures of discriminability and response bias provided by the CVLT-2
scoring program. Groups were similar in IQ and education. Multi-level
regression models were created to examine the effects of moderating
variables. The interaction between age and age group significantly
predicted response bias. Post hoc analysis indicated that increasing age
was associated with more liberal bias in the older but not in the younger
group. In the light of reported relationships between frontal regions and
both aging and response bias, we hypothesize that frontal changes may be
the underlying mechanism explaining the increase in liberal response bias
with age. (JINS, 2006, 12, 1–7.)
Neuropsychological changes following electrical injury
Authors: PLISKIN NEIL H. , AMMAR ALIA N. , FINK JOSEPH W. , HILL S. KRISTIAN , MALINA AARON C. , RAMATI ALONA , KELLEY KATHLEEN M. , LEE RAPHAEL C.
Published: March 2008

The clinical presentation of electrical injury commonly involves
physical, cognitive, and emotional complaints. Neuropsychological studies,
including case reports, have indicated that electrical injury (EI)
survivors may experience a broad range of impaired neuropsychological
functions, although this has not been clarified through controlled
investigation. In this study, we describe the neuropsychological test
findings in a series of 29 EI patients carefully screened and matched to a
group of 29 demographically similar healthy electricians. Participants
were matched by their estimated premorbid intellectual ability.
Multivariate analysis of variance was used to assess group differences in
the following neuropsychological domains: attention and mental speed,
working memory, verbal memory, visual memory, and motor skills. EI
patients performed significantly worse on composite measures of
attention/mental speed and motor skills, which could not be explained
by demographic differences, injury parameters, litigation status, or mood
disturbance. Results suggest that cognitive changes do occur in patients
suffering from electrical injury. (JINS, 2006, 12,
17–23.)
Decreased corpus callosum size in sickle cell disease: Relationship with cerebral infarcts and cognitive functioning
Authors: SCHATZ JEFFREY , BUZAN ROBERT
Published: March 2008

We assessed midsagittal corpus callosum size in sickle cell disease (SCD) and its relationship to lesion volume, lesion location, and cognitive functioning. Twenty-eight children with SCD and 16 demographic controls completed magnetic resonance imaging (MRI) and neuropsychological testing. Corpus callosum (CC) size was smaller for children with silent infarcts (n= 8) or overt stroke (n= 8) than for those without visible infarcts (n= 12) or control participants. Lesion volume was a robust predictor of IQ and other cognitive scores; total CC size did not typically add explanatory power for these measures. The size of the rostral body of the CC, however, independently predicted measures of distractibility, speeded production, and working memory. Posterior CC size was also decreased among many of the children with SCD, even in the absence of visible infarcts in this region. Brain morphology appears to provide additional information about SCD-related effects on the brain above and beyond visible infarcts. (JINS, 2006,12, 24–33.)
Neuropsychological detection of cognitive impairment: Inter-rater agreement and factors affecting clinical decision-making
Authors: TUOKKO HOLLY A. , GABRIEL GILLIAN ,   THE CSHA NEUROPSYCHOLOGY WORKING GROUP
Published: March 2008

The agreement between neuropsychologists identifying cognitive impairment (CI) in older adults was examined, as were factors influencing the classification process. Twenty four neuropsychologists in 18 study centers classified cases with or without CI after reviewing neuropsychological findings and other relevant information. All cases were participants in the third wave of the Canadian Study of Health and Aging, a study of CI in later life. For 117 randomly selected cases, a second neuropsychologist reviewed the same material and reclassified the cases. Cases given the same (concordant) or different (discordant) classifications were compared with respect to patient and rater characteristics. The inter-rater agreement was moderate (77.7% agreement, kappa = .49). On all measures of cognitive functioning, the concordant group without impairment obtained a higher mean score than the discordant group, and the discordant group obtained a higher mean score than the concordant group with impairment. For 5 out of 8 cognitive measures, the concordant group with impairment differed from the concordant group without impairment and the discordant group, but the latter two groups did not differ significantly. The findings are comparable to others in the field and highlight the need for neuropsychologists to further clarify procedures for identifying subtle, or mild, forms of cognitive impairment. (JINS, 2006,12, 72–79.)
Vigilance and fatigue following traumatic brain injury
Authors: ZIINO CARLO , PONSFORD JENNIE
Published: March 2008

Research findings have suggested that individuals with traumatic brain injury (TBI) show greater psychophysiological and subjective costs associated with performing vigilance tasks, but have not examined relationships with fatigue. The present study aimed to investigate vigilance and its relationship with subjective and objective fatigue measures. Forty-six TBI participants and 46 controls completed a 45-minute vigilance task. They also completed a subjective fatigue scale (the VAS-F) and a selective attention task before and after the vigilance task, and had their blood pressure (BP) monitored. TBI participants performed at a lower level on the vigilance task, but performed at a similar level across the duration of the task. Higher subjective fatigue ratings on the VAS-F were associated with more misses on the vigilance task for TBI participants. TBI participants showed greater increases in diastolic BP, and these were associated with greater increases in subjective fatigue ratings on the VAS-F. A subgroup of TBI participants showed a decline in performance on the vigilance task and also showed disproportionate increases in subjective fatigue. Findings provide support for the coping hypothesis, suggesting that TBI individuals expend greater psychophysiological costs in order to maintain stable performance over time, and that these costs are also associated with subjective increases in fatigue. (JINS, 2006,12, 100–110.)