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PubMed2000

Comparison of verbal and pictorial measures of hunger during fasting in normal weight and obese subjects.

OBJECTIVE: Friedman, Ulrich, and Mattes described a new pictorial instrument for assessing hunger wherein respondents outline areas on a drawing of a human figure to depict the location of their hunger sensations. The present study compared normal weight and obese individuals on the pictorial measure and on more traditional verbal hunger measures during a 22-hour fast. RESEARCH METHODS AND PROCEDURES: The pictorial measure, along with 13 verbal items assessing hunger and hunger-related symptoms, was administered to 29 normal weight college students and 46 overweight clinic patients four times during a 22-hour fast. Factor analyses of verbal hunger items produced Hunger, Somatic Symptoms, and Stomach Symptoms factors. The pictorial measure was divided into peripheral (arms, legs, head) and central (trunk) body areas. RESULTS: The increases in hunger during the fast were greater when measured using the pictorial as opposed to the verbal instrument. Correlations between and within the three verbal hunger measures and two pictorial measures were generally few in number and modest in size. The overall pattern of correlations suggested that the verbally based hunger measures more adequately reflected the experience of hunger in normal weight than in obese individuals. A significant interaction between weight status and assessment period was found for the pictorial measure, indicating that normal weight subjects experienced more bodily hunger than overweight subjects initially but experienced less hunger than obese subjects after a prolonged period of food deprivation. DISCUSSION: Although more testing is needed, these results suggest that the pictorial hunger assessment provides information about the experience of hunger that could complement information provided by traditional verbally based hunger measures.

Adult↗
PubMed1999

A figurative measure of subjective hunger sensations.

In an attempt to better characterize the subjective experience of hunger, we assessed the locus and extent of sensations associated with varying degrees of hunger. In the first study, 83 subjects indicated by marking on a drawing of a human figure where they felt hungry under hypothetical conditions of slight to extreme hunger. Approximately 55% of subjects indicated an abdominal locus with slight hunger, a proportion which increased somewhat with increasing levels of imagined hunger. The proportion of subjects indicating other or additional body sites grew significantly with increasing hunger states; for example, those identifying the head region increased from about 10-35%. In a second study, 14 subjects were fasted for 22 h and then refed. Using the drawn figures, they outlined body areas where they experienced hunger during and after fasting. The size of the abdominal area and the total body area associated with hunger sensations expanded with increasing food deprivation and contracted after refeeding. The size of the area of hunger sensation did not necessarily correlate with the degree of hunger as assessed by standard rating scales. The results indicate that the extent and locus of hunger sensations vary with fasting and feeding, and suggest that the site and size of the body areas associated with hunger sensations may provide qualitative and quantitative measures of the subjective experience of hunger not captured by analogue rating scales.

Adult↗
PubMed1990

Development of indicators to assess hunger.

Despite widespread concern about hunger in America, efforts to monitor and assess the extent of hunger have been hampered by lack of consensus on an appropriate meaning for the term hunger and by the lack of valid indicators to assess it. The first phase of the research used qualitative methods to derive a socially-appropriate definition of hunger. Thirty-two women in Upstate New York were interviewed regarding their experience with food problems and hunger. The interviews were analyzed using the constant comparative method. Results indicated that women had a narrow and a broad concept of hunger. The narrow concept focused on going without food for a specified period of time and the physical sensation of hunger. The broad one included two dimensions: household and individual hunger. Each had quantitative, qualitative, psychological, and social components. The second phase of the research used survey methodology to examine the validity and reliability of items designed to measure the conceptual definition of hunger. The survey was administered to 189 women in Upstate New York who participated in programs designed for low-income households or households in need of food. The second phase confirmed the conceptualization of hunger developed in the first phase. A subset of valid and reliable items that represented each of the major dimensions and components of hunger was identified as being useful for monitoring and assessing hunger.

Adult↗
PubMed2003

Modulation of hunger by plasma glucose and metformin.

The plasma glucose concentration is a major short-term regulator of hunger and food intake. In patients with diabetes, therapies lowering plasma glucose are frequently associated with body weight gain, suggesting that lowered plasma glucose leads to increased feelings of hunger and food intake. However, as many physiological and symptomatic responses to low plasma glucose are attenuated after repeated episodes of hypoglycemia, this may also pertain to feelings of hunger. Here we tested whether the stimulatory effect of low plasma glucose on feelings of hunger is likewise reduced by repeated episodes of hypoglycemia. As metformin has been shown to reduce plasma glucose levels without increasing body weight and also to decrease food intake, we tested for possible interacting effects of this substance with hypoglycemia-induced hunger. Feelings of hunger were assessed by rating scales during 3 consecutive hypoglycemic clamps performed on 2 consecutive d in 15 normal weight men. Subjects were tested once while being treated with 850 mg metformin twice daily and once while receiving placebo. Treatment was started 14 d before the clamp experiments and was performed in a random order and double-blind fashion. Hypoglycemia markedly enhanced feelings of hunger (P < 0.001). However, rated feelings of hunger on the first and last hypoglycemic clamps were comparable (P = 0.304). Compared with placebo, metformin decreased feelings of hunger during hypoglycemia (P = 0.015). This reduction was not associated with a decrease in posthypoglycemic food intake as measured by the number of cookies consumed after the last clamp (P = 0.676). Data indicate that the stimulatory effect of low plasma glucose on hunger is not attenuated after repeated episodes of hypoglycemia, which implies that, in contrast to other symptoms, hunger is not subject to adaptive attenuation upon repeated hypoglycemia. Metformin attenuates hypoglycemia-induced hunger, but does not appear to influence posthypoglycemic food intake.

Adult↗
PubMed2006

[Physiological and biochemical effects of intermittent fasting combined with hunger-resistant food on mice].

OBJECTIVE: To observe the physiological and biochemical effects of intermittent fasting combined with hunger-resistant food on mice, and to evaluate the safety and beneficial effects of this regimen. METHODS: One hundred and forty-four adult ICR mice were divided into 4 groups: standard feed AL group (ad libitum intake of standard feed), hunger-resistant food AL group (ad libitum intake of hunger-resistant food), standard feed IF group (feeding standard feed and fasting on alternate days), and hunger-resistant food IF group (feeding hunger-resistant food and fasting on alternate days). The experiment lasted for 4-8 weeks and all mice drank water freely. The quality of life, body weight, fasting blood glucose, serum lipid, blood routine test, liver and kidney functions as well as the viscera indexes were examined. RESULTS: Compared to the standard feed AL group, the caloric taking and the increment of body-weight were reduced (P<0.01), and the viscera indexes of the liver and kidney were elevated (P<0.05) in the hunger-resistant food AL group and the hunger-resistant food IF group, the values of fasting blood glucose were reduced in standard feed IF group and hunger-resistant food IF group (P<0.01), the value of triglycerides was reduced in hunger-resistant food IF group (P<0.05), while the quality of life, blood routine test as well as the liver and kidney functions were not obviously affected in the hunger-resistant food AL group, standard feed IF group and hunger-resistant food IF group. CONCLUSION: The regimen of intermittent fasting combined with hunger-resistant food is safe and beneficial to metabolic regulation, such as controlling body-weight and adjusting blood glucose and serum lipid. It is expected that development of this regimen will be helpful to the control of obesity and diabetes, etc.

Animals↗
PubMed2003

The influence of social norms on hunger ratings and eating.

Restrained and unrestrained eaters were exposed to fictitious hunger reports (high-hunger, low-hunger) of ostensible prior participants in the experiment. In the control condition, participants were not exposed to prior-participant reports. Participants rated their own hunger and then consumed cookies during a 'taste-test.' The fictitious hunger ratings of prior participants exerted a strong effect (p<0.001) on actual participants' hunger ratings; however, food intake was not affected by the fictitious hunger ratings (or by the actual participants' hunger ratings). We discuss the disjunction between hunger ratings and eating, specifically whether (a) hunger reports were fabricated in response to social pressure or (b) eating is controlled by factors other than hunger.

Adult↗
PubMed1998

Hunger in children in the United States: potential behavioral and emotional correlates.

OBJECTIVE: Results from a recent series of surveys from 9 states and the District of Columbia by the Community Childhood Hunger Identification Project (CCHIP) provide an estimate that 4 million American children experience prolonged periodic food insufficiency and hunger each year, 8% of the children under the age of 12 in this country. The same studies show that an additional 10 million children are at risk for hunger. The current study examined the relationship between hunger as defined by the CCHIP measure (food insufficiency attributable to constrained resources) and variables reflecting the psychosocial functioning of low-income, school-aged children. METHODS: The study group included 328 parents and children from a CCHIP study of families with at least 1 child under the age of 12 years living in the city of Pittsburgh and the surrounding Allegheny County. A two-stage area probability sampling design with standard cluster techniques was used. All parents whose child was between the ages of 6 and 12 years at the time of interview were asked to complete a Pediatric Symptom Checklist, a brief parent-report questionnaire that assesses children's emotional and behavioral symptoms. Hunger status was defined by parent responses to the standard 8 food-insufficiency questions from the CCHIP survey that are used to classify households and children as "hungry," "at-risk for hunger," or "not hungry." RESULTS: In an area probability sample of low-income families, those defined as hungry on the CCHIP measure were significantly more likely to have clinical levels of psychosocial dysfunction on the Pediatric Symptom Checklist than children defined as at-risk for hunger or not hungry. Analysis of individual items and factor scores on the Pediatric Symptom Checklist showed that virtually all behavioral, emotional, and academic problems were more prevalent in hungry children, but that aggression and anxiety had the strongest degree of association with experiences of hunger. CONCLUSION: Children from families that report multiple experiences of food insufficiency and hunger are more likely to show behavioral, emotional, and academic problems on a standardized measure of psychosocial dysfunction than children from the same low-income communities whose families do not report experiences of hunger. Although causality cannot be determined from a cross-sectional design, the strength of these findings suggests the importance of greater awareness on the part of health care providers and public health officials of the role of food insufficiency and hunger in the lives of poor children.

Affective Symptoms↗
PubMed2003

Position of the American Dietetic Association: Addressing world hunger, malnutrition, and food insecurity.

It is the position of the American Dietetic Association (ADA) that access to adequate amounts of safe, nutritious, and culturally appropriate food at all times is a fundamental human right. Hunger continues to be a worldwide problem of staggering proportions. The Association supports programs and encourages practices that combat hunger and malnutrition, produce food security, promote self-sufficiency, and are environmentally and economically sustainable. The Association is aware that hunger exists in a world of plenty and that poverty, gender inequity, ethnocentrism, racism, and the lack of political will are key constraints to solving the problems of global hunger and malnutrition. Recognizing that simplistic approaches are inadequate, the ADA identifies sustainable development as the long-term strategy to ending world hunger and achieving food security. Sustainable development requires political, economic, and social changes that include empowering the disenfranchised, widening access to assets and other resources, narrowing the gap between rich and poor, and adjusting consumption patterns so as to foster good stewardship of nature. Additionally, because the health status of future generations is related to the well-being of their mothers, achieving food security will also require increased access for women to education, adequate health care and sanitation, and economic opportunities. This position paper reviews the complex issues of global food insecurity and discusses long-term solutions for achieving world food security. Achieving the end of world hunger has been and is now within our grasp. There is sufficient food to feed everyone, and solutions can be realized now that will benefit all of humanity. As noted in the paper, most people who examine the costs of ending versus not ending world hunger are bewildered by the question of why humanity did not solve the problem a long time ago. The Association supports programs and encourages practices that combat hunger and malnutrition, produce food security, promote self-sufficiency, respect local cultures, and are environmentally and economically sustainable. The ADA recognizes that decisions and actions that dietetics professionals make as practitioners and consumers can help reduce the extent of poverty and hunger both here and abroad. This paper provides information, resources, and strategies to assist dietetics professionals in improving the public's understanding of key issues, becoming advocates of the poor, and influencing the political will to end world hunger.

Agriculture↗
PubMed2006

Characterization of obese individuals who claim to detect no relationship between their eating pattern and sensations of hunger or fullness.

OBJECTIVE: To study the phenomenon that obese subjects show considerable individual variability in their reported relationships between eating and sensations of hunger and fullness. DESIGN: A laboratory study of the relationship between eating behaviour traits and the episodic oscillations in sensations of hunger and fullness in response to obligatory, fixed energy breakfast (481 kcal) and lunch (675 kcal) meals. SUBJECTS: Obese subjects were divided into two groups based on their responses to four 'screening' questions associated with their habitual experience of hunger and fullness sensations before and after eating: those who experienced sensations of hunger and fullness related to eating (Related-R; n=20, body mass index (BMI)=42.4 kg/m(2)) and those for whom eating was not related to hunger or fullness sensations (Unrelated - UR; n=19, BMI=41.3 kg/m(2)). In addition, a control, lean group (Control - C; n=14, BMI=22.6 kg/m(2)) who experienced sensations of hunger and fullness related to eating was studied. MEASUREMENTS: The Three-Factor Eating Questionnaire (TFEQ) was used to measure the eating behaviour traits, disinhibition, restraint and hunger. Profiles of subjective appetite sensations were continuously monitored across the day using visual analogue scales. RESULTS: All groups displayed clear meal-related oscillations in subjective sensations of hunger, fullness, desire to eat and prospective consumption. In contrast, the TFEQ disinhibition and hunger scores (but not restraint scores) were significantly different (P<0.05) between the groups ((UR; D=13.5+/-0.5, H=10.0+/-0.5), R (D 7.5+/-0.6, H 6.1+/-0.4), C(D 3.7+/-0.5, H 3.7+/-0.5)). In addition, analysis of the intra-meal changes in subjective appetite sensations revealed that the UR group displayed a smaller meal-induced suppression of hunger and elevation of fullness. CONCLUSION: These data indicate that the reported relationship between eating and hunger/fullness was associated with obese individuals showing high or low disinhibition scores. In addition, the data suggest that the processes underlying disinhibition may be associated with a modulation of the recognition of meal-related satiety sensations.

Adult↗
PubMed2004

Time course of air hunger mirrors the biphasic ventilatory response to hypoxia.

Determining response dynamics of hypoxic air hunger may provide information of use in clinical practice and will improve understanding of basic dyspnea mechanisms. It is hypothesized that air hunger arises from projection of reflex brain stem ventilatory drive ("corollary discharge") to forebrain centers. If perceptual response dynamics are unmodified by events between brain stem and cortical awareness, this hypothesis predicts that air hunger will exactly track ventilatory response. Thus, during sustained hypoxia, initial increase in air hunger would be followed by a progressive decline reflecting biphasic reflex ventilatory drive. To test this prediction, we applied a sharp-onset 20-min step of normocapnic hypoxia and compared dynamic response characteristics of air hunger with that of ventilation in 10 healthy subjects. Air hunger was measured during mechanical ventilation (minute ventilation = 9 +/- 1.4 l/min; end-tidal Pco(2) = 37 +/- 2 Torr; end-tidal Po(2) = 45 +/- 7 Torr); ventilatory response was measured during separate free-breathing trials in the same subjects. Discomfort caused by "urge to breathe" was rated every 30 s on a visual analog scale. Both ventilatory and air hunger responses were modeled as delayed double exponentials corresponding to a simple linear first-order response but with a separate first-order adaptation. These models provided adequate fits to both ventilatory and air hunger data (r(2) = 0.88 and 0.66). Mean time constant and time-to-peak response for the average perceptual response (0.36 min(-1) and 3.3 min, respectively) closely matched corresponding values for the average ventilatory response (0.39 min(-1) and 3.1 min). Air hunger response to sustained hypoxia tracked ventilatory drive with a delay of approximately 30 s. Our data provide further support for the corollary discharge hypothesis for air hunger.

Adult↗
PubMed1998

Hunger in midwestern inner-city young children.

OBJECTIVE: To determine the characteristics of hunger in young children who attend ambulatory pediatric clinics in a midwestern city. DESIGN: Consecutive sample. SETTING: Ambulatory pediatric clinics of an inner-city teaching hospital. PARTICIPANTS: English-speaking caregivers of 2578 children younger than 5 years. MAIN OUTCOME MEASURE: Structured survey measures of hunger, family characteristics, assistance program use, child feeding practices, and anthropometrics. RESULTS: In this population, 171 (6.6%) were hungry, and 842 (32.7%) were at risk for hunger. Hunger status was associated with increased age (P<.001), decreased maternal education level (P=.013), maternal nonwhite race (P<.002), a history of homelessness (P<.001), and parental unemployment (P<.001). Hunger status was associated with use of Aid to Families with Dependent Children (P<.001) and food stamps (P<.001) but not with participation in The Special Supplemental Nutrition Program for Women, Infants, and Children (WIC). Results of anthropometrics indicated that mean growth percentiles were no different between hunger categories. CONCLUSIONS: Housing, dietary, and family characteristics are identifiable risk factors for early childhood hunger. Hunger cannot be identified, however, using anthropometrics. It is disconcerting that fewer hungry children and children at risk for hunger participate in WIC compared with other programs. These data suggest the potential for more aggressive identification and intervention at the primary care and social service levels to benefit hungry children.

Anthropometry↗
PubMed1999

Heritability of hunger relationships with food intake in free-living humans.

The heritability of the before and after meal self-ratings of hunger and thirst and their relationship to food intake was investigated with 110 identical and 102 fraternal same-sex and 53 fraternal mixed-gender adult twin pairs who were paid to maintain 7-day food intake diaries. From the diary reports, the total and meal intakes of food energy and the amounts of the macronutrients ingested were estimated. Subjects rated their subjective levels of hunger on a seven-point scale both before and after eating. Linear structural modeling was applied to investigate the nature and degree of genetic and environmental influences and revealed significant genetic influences on the self-rated levels of hunger both before and after the meals and the change in hunger over the meal. In addition, the relationship between hunger and intake was influenced by the genes. Significant heritabilities were found for the correlations, and the slopes of the regression lines relating before-meal hunger to meal size and also the change in hunger over the meal to intake. This indicates that hunger's effect on intake and, in turn, intake's effects on hunger are to some extent heritable. This suggests that the level of subjective experience and the individuals responses to them are influenced by the genes and become part of the total package of genetically determined physiological, socio/cultural, and psychological processes that regulate energy balance.

Adult↗
PubMed2005

The prevalence and perceived health consequences of hunger in emergency department patient populations.

OBJECTIVES: Hunger is associated with chronic poor health and may force patients to make choices that acutely impact their health. This study was conducted to determine the prevalence of hunger, some of the choices it forces, and its perceived health effects among emergency department (ED) patients. METHODS: A validated survey about hunger, choosing between food and medicine, and perceived adverse health outcomes was administered in English, Spanish, and Somali to non-critically ill ED patients or their parents. Demographics, rates of hunger, numbers of yearly ED visits, and decisions between buying commodities or medications were assessed. Relationships between variables were summarized with odds ratios (ORs), 95% confidence intervals, and logistic regression. RESULTS: Of 930 respondents, 23.7% screened positive for hunger and 17.6% bought food instead of medications. Among the hunger-positive respondents, 44% believed this choice caused illness, and of these, 69% sought ED assessment and 35% believed they were hospitalized because of this choice. Predictors of hunger were low income (OR = 3.3), illicit drug use (OR = 5.5), chronic illness (OR = 2.1), Hispanic ethnicity (OR = 1.9), and lack of insurance (OR = 1.8). Buying food instead of medicine was predicted by low income (OR = 2.5), chronic illness (OR = 2.4), and lack of insurance (OR = 3.4). Predictors of illness were chronic illness (OR = 1.8), lack of insurance (OR = 2.8), African American race (OR = 2.0), and "poor" health (OR = 1.9). CONCLUSIONS: These ED patients have high rates of hunger and often choose to buy food instead of medications. Many believe that this choice results in ED visits and hospitalizations. Socioeconomic factors may predict hunger and subsequent ill health.

Adolescent↗
PubMed2000

Child hunger in Canada: results of the 1994 National Longitudinal Survey of Children and Youth.

BACKGROUND: In Canada, hunger is believed to be rare. This study examined the prevalence of hunger among Canadian children and the characteristics of, and coping strategies used by, families with children experiencing hunger. METHODS: The data originated from the first wave of data collection for the National Longitudinal Survey of Children and Youth, conducted in 1994, which included 13,439 randomly selected Canadian families with children aged 11 years or less. The respondents were asked about the child's experience of hunger and consequent use of coping strategies. Sociodemographic and other risk factors for families experiencing hunger, use of food assistance programs and other coping strategies were analyzed by means of multiple logistic regression analysis. RESULTS: Hunger was experienced by 1.2% (206) of the families in the survey, representing 57,000 Canadian families. Single-parent families, families relying on social assistance and off-reserve Aboriginal families were overrepresented among those experiencing hunger. Hunger coexisted with the mother's poor health and activity limitation and poor child health. Parents offset the needs of their children by depriving themselves of food. INTERPRETATION: Physicians may wish to use these demographic characteristics to identify and assist families with children potentially at risk for hunger.

Activities of Daily Living↗
PubMed2006

Achieving the goal of halving global hunger by 2015.

The FAO World Food Summit (WFS) in 1996 set the goal of halving the numbers of the global population suffering hunger by the year 2015, which was later incorporated into the UN Millennium Development Goals (MDG) that commit the international community to an expanded vision of development, and one that vigorously promotes human development as the key to sustaining social and economic progress in all countries. The two targets under the first MDG goal to eradicate poverty and hunger call for halving the proportion of individuals who suffer from poverty and from hunger by 2015. This commitment is another instance of the international community through the UN system yet again renewing its efforts and setting a target and a time frame to deal with the global problem of hunger, poverty and malnutrition. To date, the efforts to reduce global hunger in the developing world have fallen far short of the pace required to meet these targets. There has no doubt been some progress and several countries in the developing world have proved that success is possible. The economic and societal costs to developing countries of not taking decisive action, and thus failing to achieve a reduction in hunger and undernutrition, including micronutrient malnutrition costs, are that every year five million children lose their lives, 220 million disability-adjusted life years are lost as a result of childhood and maternal undernutrition and billions of dollars are lost in productivity and incomes in these countries. Alongside this perennial problem in developing societies are emerging new epidemics of diet-related diseases resulting from the profound demographic changes, urbanization and the economic transition that is transforming and globalizing the food systems in these countries. Thus, many developing countries are facing new and additional challenges of co-existing hunger alongside the emergence of other forms of malnutrition. Meeting the WFS and MDG targets of achieving the goal of halving global hunger is urgent, and the question that needs to be addressed is not whether the international community can achieve this goal in time but whether it can afford not to.

Developing Countries↗
PubMed2002

Eating in the absence of hunger and overweight in girls from 5 to 7 y of age.

BACKGROUND: Eating when exposed to large portions of palatable foods in the absence of hunger has been suggested to contribute to overweight. OBJECTIVE: This research evaluated whether young girls' eating in the absence of hunger was stable across a 2-y period in middle childhood, was associated with an increased risk of overweight, and could be predicted by parents' use of restriction in child feeding. DESIGN: The participants were 192 non-Hispanic white girls and their parents, assessed when the girls were 5 and 7 y of age. The girls' eating when exposed to palatable foods in the absence of hunger was measured after they consumed a standard lunch and indicated that they were no longer hungry. RESULTS: Eating in the absence of hunger showed moderate stability across the 2-y period for most of the girls. The girls who ate large amounts of snack foods in the absence of hunger at 5 and 7 y of age were 4.6 times as likely to be overweight at both ages. Parents' reports of restricting their daughter's access to foods at age 5 y predicted girls' eating in the absence of hunger at age 7 y, even when the girls' weight status and eating in the absence of hunger at age 5 y were controlled for. CONCLUSIONS: This study provides the first evidence that young girls' eating in the absence of hunger may represent a stable phenotypic behavior of young overweight girls. In addition, these findings are consistent with previous work indicating that parents' restrictive feeding practices may contribute to this behavior.

Body Weight↗
PubMed1996

Air hunger induced by acute increase in PCO2 adapts to chronic elevation of PCO2 in ventilated humans.

Brief increases in arterial PCO2 (PaCO2) (lasting several minutes) produce a sensation of respiratory discomfort (air hunger). It is not known whether air hunger adapts to chronic changes in PaCO2. This study tested whether the level of end-tidal PCO2 (PETCO2) required to evoke air hunger would increase with chronic elevation of PETCO2 (lasting several days). Four ventilator-dependent subjects participated in a 2-wk study during which they were ventilated with air (placebo) or air rich in CO2 (CO2 exposure). Average resting PETCO2 during control periods was 25 Torr (typical for such patients); PETCO2 was 15 Torr higher during CO2 exposure. Ventilation and arterial PO2 did not differ between conditions. Periodically, we performed tests in which subjects rated the intensity of air hunger induced by brief increases in PETCO2. The increase in PETCO2 required to elicit a given air hunger rating during CO2 exposure also increased by approximately 15 Torr. That is, subjects' sensation of air hunger fully adapted to the chronic increase in PETCO2. Arterial pH did not fully return to control values during CO2 exposure. Accommodation in the chemoreceptors and neural pathways that subserve air hunger sensation may explain the adaptation of air hunger.

Adaptation, Physiological↗
PubMed2002

BOLD fMRI identifies limbic, paralimbic, and cerebellar activation during air hunger.

Air hunger (uncomfortable urge to breathe) is a component of dyspnea (shortness of breath). Three human H(2)(15)O positron emission tomography (PET) studies have identified activation of phylogenetically ancient structures in limbic and paralimbic regions during dyspnea. Other studies have shown activation of these structures during other sensations that alert the organism to urgent homeostatic imbalance: pain, thirst, and hunger for food. We employed blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) to examine activation during air hunger. fMRI conferred several advantages over PET: enhanced signal-to-noise, greater spatial resolution, and lack of ionizing radiation, enabling a greater number of trials in each subject. Six healthy men and women were mechanically ventilated at 12-14 breaths/min. The primary experiment was conducted at mean end-tidal PCO(2) of 41 Torr. Moderate to severe air hunger was evoked during 42-s epochs of lower tidal volume (mean = 0.75 L). Subjects described the sensation as "like breath-hold," "urge to breathe," and "starved for air." In the baseline condition, air hunger was consistently relieved by epochs of higher tidal volume (mean = 1.47 L). A control experiment in the same subjects under a background of mild hypocapnia (mean end-tidal PCO(2) = 33 Torr) employed similar tidal volumes but did not evoke air hunger, controlling for stimulus variables not related to dyspnea. During each experiment, we maintained constant end-tidal PCO(2) and PO(2) to avoid systematic changes in global cerebral blood flow. Whole-brain images were acquired every 5 s (T2*, 56 slices, voxel resolution 3 x 3 x 3 mm). Activations associated with air hunger were determined using voxel-based interaction analysis of covariance that compared data between primary and control experiments (SPM99). We detected activations not seen in the earlier PET study using a similar air hunger stimulus (Banzett et al. 2000). Limbic and paralimbic loci activated in the present study were within anterior insula (seen in all 3 published studies of dyspnea), anterior cingulate, operculum, cerebellum, amygdala, thalamus, and basal ganglia. Elements of frontoparietal attentional networks were also identified. The consistency of anterior insular activation across subjects in this study and across published studies suggests that the insula is essential to dyspnea perception, although present data suggest that the insula acts in concert with a larger neural network.

Adult↗