Parent-offspring similarity in hunger and thirst sensations.

The internal (i.e., interoceptive) sensations that characterise hunger vary between people, and this may also be the case for thirst, although it has not been so well explored. There are probably both heritable and learning-based causes for this interoceptive variability. Consequently, it would seem plausible that parents and their offspring would have more similar patterns of hunger and thirst than pairs of strangers. We tested this idea, in addition to exploring its potential moderating variables, by studying the similarity of self-reported hunger and thirst sensations in 170 students and their primary caregivers from childhood. Both students and caregivers completed the same online-survey, covering hunger and thirst sensations, beliefs about the causes of hunger and thirst, the Three Factor Eating Questionnaire (revised) and demographic data. We find evidence of robust student-caregiver similarity in interoceptive hunger and thirst sensations (medium effect sizes), with these being moderated by caregiver beliefs about the homeostatic nature of each state (medium effect sizes). This suggests a potential role for caregivers in the development of their offspring's interoceptive cues for hunger and for thirst. In addition, thirst, like hunger, appears to be multidimensional, and varies between people. The implications of these findings are discussed.

Vulnerability of the Hippocampus to Insults: Links to Blood-Brain Barrier Dysfunction.

The hippocampus is a critical brain substrate for learning and memory; events that harm the hippocampus can seriously impair mental and behavioral functioning. Hippocampal pathophysiologies have been identified as potential causes and effects of a remarkably diverse array of medical diseases, psychological disorders, and environmental sources of damage. It may be that the hippocampus is more vulnerable than other brain areas to insults that are related to these conditions. One purpose of this review is to assess the vulnerability of the hippocampus to the most prevalent types of insults in multiple biomedical domains (i.e., neuroactive pathogens, neurotoxins, neurological conditions, trauma, aging, neurodegenerative disease, acquired brain injury, mental health conditions, endocrine disorders, developmental disabilities, nutrition) and to evaluate whether these insults affect the hippocampus first and more prominently compared to other brain loci. A second purpose is to consider the role of hippocampal blood-brain barrier (BBB) breakdown in either causing or worsening the harmful effects of each insult. Recent research suggests that the hippocampal BBB is more fragile compared to other brain areas and may also be more prone to the disruption of the transport mechanisms that act to maintain the internal milieu. Moreover, a compromised BBB could be a factor that is common to many different types of insults. Our analysis indicates that the hippocampus is more vulnerable to insults compared to other parts of the brain, and that developing interventions that protect the hippocampal BBB may help to prevent or ameliorate the harmful effects of many insults on memory and cognition.

Predictors of state-based changes in wanting and liking.

People report wanting food when they are hungry, and on eating it they typically report liking the experience. After eating, both wanting and liking decline, but wanting declines to a greater extent, which we term the 'affective discrepancy effect'. In this study we examine the predictors - state, sensory and memory-based - of these affective changes. Hungry participants undertook three tasks: (1) written recollections of what certain foods are like to eat; (2) ratings of wanting and expected flavour liking and fillingness when looking at snacks, and ratings of food and flavour liking when eating them; (3) ratings of bodily state. These tasks were then repeated after lunch. State-based changes in food liking were best predicted by changes in flavour liking. For state-based change in wanting, memory-based information about flavour liking and fillingness from tasks (1) and (2) were all significant predictors. For recollections about eating (task 1), mentions of food fillingness significantly increased pre-to post-lunch and this was the best predictor of the affective discrepancy effect. Recollections of food fillingness are state-dependent, and can arise unbidden (i.e., such recollective content was unprompted). This may reflect one way that memory may selectively influence wanting, and hence whether food intake is initiated or not.

Situational, emotional, and individual dispositions to weight gain in people with hoarding problems.

OBJECTIVES: Individuals with hoarding disorder are more likely to be overweight or obese than the general population for unknown reasons. METHODS: One hundred and twenty-nine individuals (Hoarding Group: n = 63; Control Group: n = 66) completed self-report measures and were offered snacks in a tidy and a cluttered environment in a counterbalanced order. Groups were based on the self-reporting of high or low hoarding symptoms. RESULTS: The hoarding group reported being less able to use their kitchen and prepare food at home and experiencing more impulsivity, distress intolerance and problematic eating beliefs than did the control group. The hoarding group consumed more cookies in the tidy room, whereas the control group consumed more cookies in the cluttered room. Greater impulsivity, distress intolerance and problematic body and eating beliefs were related to greater cookie consumption for the hoarding group. CONCLUSIONS: Early interventions that help individuals to tolerate distress and to engage in goal-directed behaviour regardless of their emotional state may have benefits for both hoarding and eating behaviour. We encourage future researchers to examine this hypothesis.

The development of interoceptive hunger signals.

Hunger is often reported when people experience certain internal sensations (e.g., fatigue) or when they anticipate that a food will be good to eat. The latter results from associative learning, while the former was thought to signal an energy deficit. However, energy-deficit models of hunger are not well supported, so if interoceptive hungers are not "fuel gauges," what are they? We examined an alternate perspective, where internal states signaling hunger, which are quite diverse, are learned during childhood. A basic prediction from this idea is offspring-caregiver similarity, which should be evident if caregivers teach their child the meaning of internal hunger cues. We tested 111 university student offspring-primary caregiver pairs, by having them complete a survey about their internal hunger states, alongside other information that may moderate this relationship (i.e., gender, body mass index, eating attitudes, and beliefs about hunger). We observed substantial similarity between offspring-caregiver pairs (Cohen's ds from 0.33 to 1.55), with the main moderator being beliefs about an energy-needs model of hunger, which tended to increase similarity. We discuss whether these findings may also reflect heritable influences, the form that any learning might take, and the implications for child feeding practices.

Appetitive interoception, the hippocampus and western-style diet.

Obesity, Type 2 diabetes and other metabolic disorders continue to pose serious challenges to human health and well-being. An important source of these challenges is the overconsumption of saturated fats and sugar, main staples of what has been called the Western-style diet (WD). The current paper describes a theoretical model and supporting evidence that links intake of a WD to interference with a specific brain substrate that underlies processing of interoceptive signals of hunger and satiety. We review findings from rats and humans that the capacity of these signals to modulate the strength of appetitive and eating behavior depends on the functional integrity of the hippocampus and the learning memory operations it performs. Important among these operations is the use of contextual information to retrieve memories that are associated with other events. Within our framework, satiety provides an interoceptive context that informs animals that food cues and appetitive behavior will not be followed by rewarding postingestive outcomes. This serves to prevent those cues and responses from retrieving those reward memories. The findings reviewed provide evidence that consuming a WD and the high amounts of saturated fat and sugar it contains (a) is associated with the emergence of pathophysiologies to which the hippocampus appears selectively vulnerable (b) impairs hippocampal-dependent learning and memory (HDLM) and (c) weakens behavioral control by interoceptive hunger and satiety contextual stimuli. It is hypothesized that these consequences of WD intake may establish the conditions for a vicious cycle of further WD intake, obesity, and potentially cognitive decline.

Recollections about food when hungry and sated.

Memory processes may have several roles in appetite regulation. Here we examine one such role, derived from the animal literature, in which satiety cues lead to the inhibition of rewarding food-related memories. We tested this idea over three studies (n's of 58, 67, 50 respectively), by presenting participants with visual or verbal food cues, and asking them to describe what these foods were like to eat. This recollection task was undertaken hungry and sated. The resulting recollections were then coded and contrasted across state. Irrespective of state, participants took the same time to make their recollections, they were of similar length and included the same amount of sensory detail and affective content. However, in all three studies, sated recollections tended to include more reports about how filling a food would be. This increase in reports of food fillingness across state, was significantly correlated with increases in reports of stomach distension across state. While these results are consistent with the operation of memory inhibition, a further possibility is considered, whereby interoceptive satiety cues are integrated into food-related recollections (but not other recollections) to form a memory-inteorception-combination, thereby drawing attention to the consequences of eating when sated.

Elucidating knowledge and beliefs about obesity and eating disorders among key stakeholders: paving the way for an integrated approach to health promotion.

BACKGROUND: Understanding the knowledge and beliefs of key stakeholders is crucial in developing effective public health interventions. Knowledge and beliefs about obesity and eating disorders (EDs) have rarely been considered, despite increasing awareness of the need for integrated health promotion programs. We investigated key aspects of knowledge and beliefs about obesity and EDs among key stakeholders in Australia. METHODS: Using a semi-structured question guide, eight focus groups and seven individual interviews were conducted with 62 participants including health professionals, personal trainers, teachers and consumer group representatives. An inductive thematic approach was used for data analysis. RESULTS: The findings suggest that, relative to obesity, EDs are poorly understood among teachers, personal trainers, and certain health professionals. Areas of commonality and distinction between the two conditions were identified. Integrated health promotion efforts that focus on shared risk (e.g., low self-esteem, body dissatisfaction) and protective (e.g., healthy eating, regular exercise) factors were supported. Suggested target groups for such efforts included young children, adolescents and parents. CONCLUSIONS: The findings indicate areas where the EDs and obesity fields have common ground and can work together in developing integrated health promotion programs.

Wanting and liking for sugar sweetened beverages and snacks differ following depletion and repletion with energy and fluids.

Drinking sugar-sweetened beverages (SSBs) seems to uniquely contribute to excess weight gain, and several mechanisms have been proposed to account for this. Here we examine a further proposal, namely that explicit wanting and liking for SSBs may be less sensitive to changes in physiological state, when contrasted to equi-palatable solid sweet snacks. Study 1 explored this by having participants rate wanting for (on seeing) and liking of (on tasting) several SSBs and snacks, before and after receiving a solid lunch with ad libitum water. Participant reports of hunger and thirst, obtained at multiple time-points, equally reduced across lunch. Wanting for the snacks decreased significantly more across lunch than liking, but for the SSBs, wanting and liking decreased in parallel. Study 2 engineered a far more dramatic alteration in thirst, by using fluid deprivation, a liquid lunch, and encouraging drinking to satiation. This time, reduction in thirst exceeded reduction in hunger. However, all this served to achieve was an equivalent change across lunch for snacks and SSBs, with wanting reducing more than liking now for both. These findings suggest that changes in wanting, relative to liking, for SSBs, are less sensitive to alterations in physiological state than equi-palatable solid snacks, enhancing the chance of consumption.

Cross-Modal Associations Between Real Tastes and Colors.

People make reliable and consistent matches between taste and color. However, in contrast to other cross-modal correspondences, all of the research to date has used only taste words (and often color words too), potentially limiting our understanding of how taste-color matches arise. Here, participants sampled the 5 basic tastes, at 3 concentration steps, and selected their best matching color from a color wheel. This test was repeated, and in addition, participants evaluated the valence of the taste and their color choice, as well as the qualities/intensities of the taste stimuli. Participants were then presented with taste names and asked to generate the best matching color name, as well as reporting how they made their earlier choices. Color selections were reliable and consistent and closely followed those based on taste word matches obtained in this and prior studies. Most participants reported basing their color choices on their associated taste-object (often foods). There was marked similarity in valence between taste and color choices, and the saturation of color choices was related to tastant concentration. We discuss what drives color-taste pairings, with learning suggested as one possible mechanism.

Hippocampal dependent neuropsychological tests and their relationship to measures of cardiac and self-report interoception.

The hippocampus is involved in interoceptive processing (i.e., perceiving internal bodily states), with much of this evidence relating to hunger and fullness. Here we examine whether cardiac and self-report measures of interoception are related to two measures of hippocampal dependent learning and memory (HDLM) - the Rey Auditory Verbal Learning Test (RAVLT) and Logical Memory. Healthy adults completed a neuropsychological test battery including all of these measures, along with assessments of intelligence and executive function. Biographical, medical and psychological-related data that might confound detecting an HDLM-interoception relationship was also collected. Both measures of HDLM were associated with cardiac interoception after controlling for confounding variables. More accurate cardiac interoception was linked to better HDLM performance. On the self-report measure of interoception, better performance on the RAVLT was associated with better-reported attention regulation, consistent with the hippocampus's known role in mindfulness. Overall, these findings suggest hippocampal involvement in cardiac and self-report interoceptive capacity. The broader functional role of the hippocampus in interoception is discussed.

Experimental manipulation of visual attention affects body size adaptation but not body dissatisfaction.

OBJECTIVE: Prolonged exposure to large/small bodies causes aftereffects in perceived body size. Outside the laboratory, individuals repeatedly exposed to small (large) bodies tend to over- (under-) estimate their size and exhibit increased (decreased) body dissatisfaction. Why, among individuals exposed to approximately equivalent distributions of body sizes, only some develop body size and shape misperception and/or body dissatisfaction is not yet fully understood. METHOD: We exposed 61 women to high and low adiposity bodies simultaneously, instructing half to attend to high, and half to low adiposity bodies. RESULTS: Participants in the high adiposity attention condition's perception of "normal" body size significantly increased in adiposity, and vice versa. DISCUSSION: This suggests that visual attention moderates body size aftereffects. Interventions encouraging visual attention to more realistic ranges of bodies may therefore reduce body misperception. No change in body dissatisfaction was found, suggesting that changes in the perceptual component (misperception) may not necessarily affect the attitudinal component (dissatisfaction) of body image distortion.

Chemosensory Abilities in Consumers of a Western-Style Diet.

People vary in their habitual diet and also in their chemosensory abilities. In this study, we examined whether consumption of a Western-style diet, rich in saturated fat and added sugar, is associated with either poorer or different patterns of chemosensory perception, relative to people who consume a healthier diet. Participants were selected based on a food frequency questionnaire, which established whether they were likely to consume a diet either higher or lower in saturated fat and added sugar. Eighty-seven participants were tested for olfactory ability (threshold, discrimination, and identification), gustatory ability (PROP sensitivity, taste intensity, quality, and hedonics), and flavor processing (using dairy fat-sugar-odor mixtures). A Western-style diet was associated with poorer odor identification ability, greater PROP sensitivity, poorer fat discrimination, different patterns of sweetness taste enhancement, and hedonic differences in taste and flavor perception. No differences were evident for odor discrimination or threshold, in perception of taste intensity/quality (excluding PROP) or the ability of fats to affect flavor perception. The significant relationships were of small to moderate effect size, and would be expected to work against consuming a healthier diet. The discussion focuses on whether these diet-related differences precede adoption of a Western-style diet and/or are a consequence of it.

Interoceptive awareness and its relationship to hippocampal dependent processes.

Many neuropsychological and animal lesion studies point to the hippocampus as being critical for mediating interoceptive awareness, while neuroimaging studies have been used to argue for the importance of the insula and anterior cingulate cortex. Here, using healthy young adults - as with the neuroimaging data - we tested for an association between performance on a hippocampal dependent learning and memory (HDLM) measure (logical memory percent retention) and interoceptive awareness assessed on three tasks - heart rate tracking, water loading and the Multidimensional Assessment of Interoceptive Awareness questionnaire (MAIA). After controlling for other relevant potentially confounding variables, we found significant associations between both the water loading and MAIA measures (which were both correlated) and HDLM performance. These findings imply that hippocampal dependent processes are involved in interoceptive awareness in healthy young adults. More tentatively, they suggest that medial temporal lobe structures may mediate interoceptive tasks that involve ingestion and/or integration of past and current state-based information.

Perception of odor-induced tastes following insular cortex lesion.

Lesions of the insula can affect olfaction and gustation. Here, we examined the effect of insula lesions on taste and taste-like experiences generated via smelling (i.e., odor-induced tastes) in patients with focal insula lesions and intact olfaction. From a set of 16 patients with lesions to the insula, we found 7 (6 with right-sided lesions) who performed normally on various olfactory measures. These were compared to 42 normal control subjects on tests of gustatory and odor-induced taste perception as well as control measures. The patients were impaired relative to controls on most gustatory measures. They were also impaired on tests of odor-induced taste perception, primarily for stimuli presented on the left side. Examining cases individually revealed evidence of a dissociation: two patients exhibited no impairment in odor-induced taste perception in spite of gustatory deficits. Together, these findings suggest that the insula mediates taste recognition, hedonics, and intensity judgments as well as odor-induced taste perception. However, the areas responsible for aspects of taste perception and those responsible for odor-induced taste do not fully overlap each other and they are also independent of olfactory areas.

The relationship between neuropsychological functioning and FDG-PET hypometabolism in intractable mesial temporal lobe epilepsy.

We examined the relationship between baseline neuropsychological functioning and 18-fluorodeoxyglucose positron emission tomography (FDG-PET) in intractable mesial temporal lobe epilepsy (MTLE). We hypothesized relationships between dominant temporal lobe hypometabolism and verbal memory and between nondominant temporal lobe hypometabolism and nonverbal memory in line with the lateralized material-specific model of memory deficits in MTLE. We also hypothesized an association between performance on frontal lobe neuropsychological tests and prefrontal hypometabolism. Thirty-two patients who had undergone temporal lobectomy for treatment of MTLE and who completed both presurgical FDG-PET and comprehensive neuropsychological investigations with widely used standardized measures were included. Age-adjusted composite measures were calculated for verbal memory, nonverbal memory, relative material-specific memory, IQ, executive function, attention/working memory, and psychomotor speed. Fluorodeoxyglucose positron emission tomography was analyzed with statistical parametric mapping (SPM) to identify hypometabolism relative to healthy controls. Pearson's correlation was used to determine the relationship between regions of hypometabolism and neuropsychological functioning. Dominant temporal lobe hypometabolism was associated with relatively inferior verbal memory, while nondominant temporal lobe hypometabolism was associated with inferior nonverbal memory. No relationship was found between performance on any frontal lobe measures and prefrontal hypometabolism. Statistical parametric mapping-quantified lateralized temporal lobe hypometabolism correlates with material-specific episodic memory impairment in MTLE. In contrast, prefrontal hypometabolism is not associated with performance on frontal lobe measures. We suggest that this is because frontal lobe neuropsychology tests may not be good measures of isolated frontal lobe functioning.

A systematic review of longer-term dietary interventions on human cognitive function: Emerging patterns and future directions.

Cognitive function may be affected by long-term diet and most of the support for this idea is derived from human correlational studies and animal prescribed diet studies. To date there has been no systematic examination of human experimental studies that examine whether a prescribed long-term (24 h+) diet can cause changes in cognitive function. Here, we review the experimental evidence of long-term changes in cognition following prescribed diet interventions. A total of 30 diet interventions were identified and reviewed. Measures of working memory, long-term memory, and attention appeared most sensitive to dietary manipulation, but there was considerable variability in outcome. Additionally, energy and fat intake manipulations tended to influence performance on these measures to the greatest degree. This review also serves to identify factors that should be considered in designing future diet-cognition studies. We also suggest a series of cognitive tests based on this review and indicate potentially profitable directions to take the diet-cognition literature.

Individual differences in the interoceptive states of hunger, fullness and thirst.

Interoception is the ability to perceive internal bodily states. This involves the detection and awareness of static and changing afferent signals from the viscera, motivational states, affective reactions, and associated cognitions. We examined whether there are individual differences in any or all of these aspects of ingestion-related interoception and their possible causes. Individual variation in almost all aspects of interoception was documented for hunger, fullness and thirst - including how participants use, prioritise and integrate visceral, motivational, affective and cognitive information. Individual differences may arise from multiple causes, including genetic influences, developmental changes hypothesised to result from child feeding practices, and from conditions such as depression, anxiety, eating disorders and certain subtypes of obesity. A nutritionally poor diet, and dietary restraint, may also affect ingestion-related interoception. Finally, certain forms of brain injury, notably to the medial temporal lobes are associated with impaired ingestion-related interoception. We conclude by examining the practical and theoretical consequences of these individual differences.

The cognitive profile of occipital lobe epilepsy and the selective association of left temporal lobe hypometabolism with verbal memory impairment.

We investigated the cognitive profile of structural occipital lobe epilepsy (OLE) and whether verbal memory impairment is selectively associated with left temporal lobe hypometabolism on [18F]-fluorodeoxyglucose positron emission tomography (FDG-PET). Nine patients with OLE, ages 8-29 years, completed presurgical neuropsychological assessment. Composite measures were calculated for intelligence quotient (IQ), speed, attention, verbal memory, nonverbal memory, and executive functioning. In addition, the Wisconsin Card Sorting Test (WCST) was used as a specific measure of frontal lobe functioning. Presurgical FDG-PET was analyzed with statistical parametric mapping in 8 patients relative to 16 healthy volunteers. Mild impairments were evident for IQ, speed, attention, and executive functioning. Four patients demonstrated moderate or severe verbal memory impairment. Temporal lobe hypometabolism was found in seven of eight patients. Poorer verbal memory was associated with left temporal lobe hypometabolism (p = 0.002), which was stronger (p = 0.03 and p = 0.005, respectively) than the association of left temporal lobe hypometabolism with executive functioning or with performance on the WCST. OLE is associated with widespread cognitive comorbidity, suggesting cortical dysfunction beyond the occipital lobe. Verbal memory impairment is selectively associated with left temporal lobe hypometabolism in OLE, supporting a link between neuropsychological dysfunction and remote hypometabolism in focal epilepsy.

Evidence that phenomenal olfactory content exceeds what can later be accessed.

Visual experience is information rich, but only a small proportion is available for later access. We tested for this distinction in olfaction. In two experiments (E1&2), participants undertook trials rating an odor's features (e.g., how banana-like?), the during-smelling-profile, followed by an after-smelling-profile, upon the odor's removal. On some trials during and after-smelling-profiles were identical and on others they were different. Each trial with a particular odor was repeated. For half the odors both trials were identical (congruent) and for the remainder, one was different and the other identical (incongruent). Crucially, the after-smelling-profile was always the same for each odor, allowing reliability to be measured. E1&2 revealed that incongruent profiles were the least reliable. Attempting to access particular odor features in an odor's absence is harder if those features were not attended during smelling. This suggests more information is available during smelling, than can be accessed after the odors removal.