Ilse M.T. Nijs

Differences in attention to food and food intake between overweight/obese and normal-weight females under conditions of hunger and satiety.

Starting from an addiction model of obesity, the present study examined differences in attention for food-related stimuli and food intake between overweight/obese and normal-weight women under conditions of hunger and satiety. Twenty-six overweight/obese (BMI: 30.00+/-4.62) and 40 normal-weight (BMI: 20.63+/-1.14) females were randomly assigned to a condition of hunger or satiety. Three indexes of attention were employed, all including pictures of food items: an eye-tracking paradigm (gaze direction and duration), a visual probe task (reaction times), and a recording of electrophysiological brain activity (amplitude of the P300 event-related potential). In addition, the acute food intake of participants was assessed using a bogus taste task. In general, an attentional bias towards food pictures was found in all participants. No differences between groups or conditions were observed in the eye-tracking data. The visual probe task revealed an enhanced automatic orientation towards food cues in hungry versus satiated, and in overweight/obese versus normal-weight individuals, but no differences between groups or conditions in maintained attention. The P300 amplitude showed that only in normal-weight participants the intentional allocation of attention to food pictures was enhanced in hunger versus satiety. In hungry overweight/obese participants, the P300 bias for food pictures was not clearly present, although an increased food intake was observed especially in this group. In conclusion, various attention-related tasks yielded various results, suggesting that they measure different underlying processes. Strikingly, overweight/obese individuals appear to automatically direct their attention to food-related stimuli, to a greater extent than normal-weight individuals, particularly when food-deprived. Speculatively, hungry overweight/obese individuals also appear to use cognitive strategies to reduce a maintained attentional bias for food stimuli, perhaps in an attempt to prevent disinhibited food intake. However, in order to draw firm conclusions, replication studies are needed.

Impulsivity is associated with behavioral decision-making deficits

Impaired decision-making is a key-feature of many neuropsychiatric disorders. In the present study, we examined task performance in a healthy population consisting of those whose scores indicated high and low impulsivity on several behavioral decision-making tasks reflecting orbitofrontal functioning. The measures included tasks that assess decision-making with and without a learning component and choice flexibility. The results show that subjects high on impulsivity display an overall deficit in their decision-making performance as compared with subjects low on impulsivity. More specifically, subjects with high impulsivity show weaknesses in learning of reward and punishment associations in order to make appropriate decisions (reversal-learning task and Iowa Gambling Task), and impaired adaptation of choice behavior according to changes in stimulus-reward contingencies (reversal-learning task). Simple, non-learning, components of reward- and punishment-based decision-making (Rogers Decision-Making Task) seem to be relatively unaffected. Above all, the results indicate that impulsivity is associated with a decreased ability to alter choice behavior in response to fluctuations in reward contingency. The findings add further evidence to the notion that trait impulsivity is associated with decision-making, a function of the orbitofrontal cortex.

The modified Trait and State Food-Cravings Questionnaires : Development and validation of a general index of food craving

In the present study, the multidimensional Trait and State Food Cravings Questionnaires (FCQ-T and FCQ-S), as developed by Cepeda-Benito, Gleaves, Williams, and Erath, [2000. The development and validation of the State and Trait Food Cravings Questionnaires. Behavior Therapy, 31, 151-173], were modified in order to construct an index of general food craving instead of specific food craving. The factor structure, validity and reliability of the modified questionnaires, renamed as the Trait and State General Food Cravings Questionnaires (G-FCQ-T and G-FCQ-S), were investigated in three separate studies. Firstly, exploratory factor analyses were conducted, which yielded a G-FCQ-T with a four-factor structure, that was considerably shorter as compared to the original (nine-factor) FCQ-T, and a G-FCQ-S of which the factor structure was highly comparable to the original FCQ-S. Secondly, in an attempt to replicate the factor structures of the G-FCQ-T and the G-FCQ-S as found in Study 1, confirmative factor analyses were performed. Results indicated adequate fits for both questionnaires. In addition, the test-retest reliability of both versions was satisfactory and an analysis of the construct validity generally revealed the expected results. In Study 3, the validity of the state version of the G-FCQ was further investigated by relating scores on this questionnaire to indices of food deprivation and satiation. Results indicated that the G-FCQ-S indeed measures food craving as a variable state, which is influenced by situational and temporal variables. Altogether, it can be concluded that the G-FCQ-T and G-FCQ-S are both reliable and valid measures of general trait-like and state-dependent food craving.

Food cue-elicited brain potentials in obese and healthy-weight individuals

The main objective of this study was to investigate, by means of event-related potentials (ERPs), whether obese individuals process food-related information differently as compared to normal-weight individuals. Because amplitudes of late positive ERP components (P3, LPP) reflect motivational tendencies, obese participants were expected to display enlarged P3 and LPP amplitudes towards food pictures. Obese and normal-weight adults were exposed to pictures of food and control items, while EEG was recorded. Subjective levels of food craving and hunger were also assessed. While there were no differences in ERP amplitudes between obese and normal-weight individuals, significantly larger P3 and LPP amplitudes were elicited by pictures of food items as compared to control pictures. Positive correlations were found between P3 and LPP amplitudes and self-reported increases of hunger. It was concluded that food-related information is processed differently in the brain as compared to non-food-related information, in a manner that reflects the natural motivational value of food. In the present study, there was no indication of an electrophysiological or subjective hyper-reactivity to food cues in obese adults.

Enhanced processing of food-related pictures in female external eaters

The main purpose of the present study was to investigate differences in the processing of food-related pictures between women with high and low scores on a scale of external eating. Electro-encephalographic brain activity was recorded, while participants were actively exposed to pictures of food items and control pictures. The amplitude of the P300 component of the even-related potentials was used as an index of motivation-related information processing. An enlarged P300 wave to food-related pictures was found in high external eaters as compared to low external eaters at several parieto-occipital electrode positions. No group differences in P300 amplitudes were found to neutral control pictures or pleasant, motivationally salient control pictures. It can be concluded that external eaters display an enhanced attentional processing of food-related information. The findings are discussed within an incentive sensitization model of overeating behavior.

Attentional Processing of Food Cues in Overweight and Obese Individuals

The incentive sensitization model of obesity hypothesizes that obese individuals in the western world have acquired an enhanced attention bias to food cues, because of the overwhelming exposure to food. This article gives an overview of recent studies regarding attention to food and obesity. In general, an interesting approach-avoidance pattern in food-related attention has been found in overweight/obese individuals in a number of studies. However, it should be noted that study results are contradictory. This might be due to methodological issues, such as the choice of attention measurements, possibly tapping different underlying components of information processing. Although attention research is challenging, researchers are encouraged to further explore important issues, such as the exact circumstances in which obese persons demonstrate enhanced attention to food, the directional relationship between food-related attention bias, overeating and weight gain, and the underlying involvement of the reward system. Knowledge on these issues could help improve treatment programs.

Effect of hedonic tone on event-related potential measures of cognitive processing

Anhedonia, the inability to experience pleasure, is a core feature of several psychiatric disorders such as schizophrenia, depression, and substance dependence. Furthermore, it has been suggested that anhedonia is an important predictor of schizophrenia. Anhedonia has been associated with information-processing deficits, especially attentional deficits, which may predispose for schizophrenia. In the present study, event-related potentials (ERPs) were used to examine the influence of hedonic tone on information-processing characteristics in a sample of healthy individuals. Thirty-five healthy subjects were divided into two groups based on their scores on the Snaith-Hamilton Pleasure Scale (SHAPS). Cognitive functions were measured during an active visual oddball paradigm. It was found that both early, middle and late ERP components of subjects with low levels of hedonic tone were attenuated compared with ERPs of subjects with high levels of hedonic tone. These findings suggest that decreased hedonic tone is associated with reductions in both automatic and effortful cognitive processing of relevant stimuli. Consequences of these findings for the vulnerability to psychopathology are discussed.

Electrophysiology of appetitive taste and appetitive taste conditioning in humans

The present study examines two novel aspects of appetitive processing and conditioning: the electrophysiological response to (a) the appetitive taste of a sweet fluid and (b) appetitively/taste conditioned visual stimuli. Event-related potentials (ERPs) were recorded from 32 subjects while they performed a taste conditioning task, in which two symbols were paired with a sweet or a neutral fluid. The results show a clear P1/N1/P2 complex, and a late positive potential (P3) with maxima at right fronto-central electrode sites, in response to the taste stimuli. Of these components particularly the P3 showed robust differences between the sweet and neutral taste. In addition, the electrophysiological response to the taste conditioned stimuli (CS), also showed the expected differences for both P2 and P3 at frontocentral electrodes. The present data demonstrate that the employed paradigm is a useful methodology to study the electrophysiological responses to unconditioned appetitive stimuli. Since appetitive conditioning is assumed to be disturbed in many psychopathological conditions, such as substance dependence, depression and eating disorders, this paradigm could be employed to get more insight in these conditions in humans.

Processing of pleasant information can be as fast and strong as unpleasant information: implications for the negativity bias

Several theoretical accounts state that negative or unpleasant information is processed ‘faster’ and activates more attentional resources than neutral and positive information. This notion is confirmed by several experimental studies. However, these studies did not employ equal values of emotional salience and arousal for positive and negative stimuli. In the present study we examine whether positive stimuli (erotic bodies) are processed as fast and strongly as negative information (mutilated bodies) when equally arousing, biologically relevant stimuli are used. Electrophysiological correlates of the processing of biologically relevant high-arousing emotional stimuli are studied using Event-Related Brain Potentials (ERPs). Results showed that both pleasant and unpleasant stimuli are processed fast and preferentially in the brain, within 100-200 ms after stimulus onset. These studies indicate that, on the electrophysiological level, pleasant stimuli are processed as ‘fast and strongly’ as unpleasant stimuli if arousal values of the stimuli are high. Implications of these findings for theories of emotion and psychopathology are discussed. (Netherlands Journal of Psychology, 64, 169-177.).

BIS/BAS sensitivity and the P300 event-related brain potential

Abstract. Both a reduced amplitude of the P300 event-related potential component and a highly impulsive personality are known to be strong predictive markers for substance abuse and related psychiatric disorders. Because of this common link to externalizing psychopathology, a significant negative association between the P300 amplitude and personality measures related to behavioral disinhibition is expected. The present study investigated correlations between the visual P300 amplitude and the personality dimensions of Behavioral Approach System (BAS) sensitivity and Behavioral Inhibition System (BIS) sensitivity among healthy subjects (N = 44; mean age = 24 ± 4.93 years). To measure BIS and BAS sensitivity the BIS/BAS scales were used. Significant positive correlations were found between BAS sensitivity and P300 amplitude at both anterior and posterior scalp locations above the right hemisphere. There were no significant correlations between P300 amplitude and BIS sensitivity. Results are discussed in ligh...