Sight Of Food Research Articles

Regional cerebral blood flow during exposure to food in obese binge eating women

Cerebral responses elicited by the sight of food were evaluated in eight obese binge eating, 11 obese and 12 normal-weight non-binge eating women. Regional cerebral blood flow (rCBF) was mapped while the subjects were looking at a picture of a landscape (control) or at a portion of food (food exposure), and was measured by [ 99mTc]ethyl-cysteine-dimer and single photon emission computed tomography. Exposure to food was associated with different changes in the cerebral blood flow (normalized to mean cerebellar counts) of the right and left hemispheres in the obese binge eating than in the obese or normal-weight non-binge eating women. As compared with the non-binge eating groups, the obese binge eating women had, due to food exposure, a greater increase in the cerebral blood flow in the left than right hemisphere, especially in the frontal and pre-frontal regions. In addition, strong linear correlations were observed in this group between the rCBF of the left frontal and pre-frontal regions and the increase in the feeling of hunger during the exposure to food. Left hemisphere and its frontal and pre-frontal regions could thus play a role in binge eating behavior in humans.

Regional cerebral blood flow during food exposure in obese and normal-weight women.

The cerebral responses elicited by the sight of food and food-related cues are poorly known in humans. Therefore, regional cerebral blood flow (rCBF) was measured during food exposure in 11 obese and 12 normal-weight women. The rCBF was mapped while the subject was looking at a picture of a landscape (control) or at a portion of food (food exposure), and was measured by 99mTc-ethyl-cysteine-dimer single photon emission computed tomography. In the obese women, the rCBF was higher in the right parietal and temporal cortices during the food exposure than in the control condition. In addition, in the obese women the activation of the right parietal cortex was associated with an enhanced feeling of hunger when looking at food. No such changes or associations were seen in the normal-weight women. In conclusion, exposure to food is associated with increases in the rCBF of right parietal and temporal cortices in obese women, but not in normal-weight women.

Postbite elevation in tongue-flicking rate by an iguanian lizard,Dipsosaurus dorsalis

The herbivorous iguanid lizardDipsosaurus dorsalis exhibited PETF (postbite elevation in tongue-flicking rate), an increase in tongue-flicking rate after experimental removal from the mouth of food that had been bitten. This was demonstrated by a significantly higher tongue-flick rate after having bitten food than in three experimental conditions controlling for responses to the experimental setting, sight of food, and mechanical disturbance caused by the experimental removal of food from a lizard's mouth. As in most other families of lizards, PETF was brief, occurring only during the first minute. Lizards are divided into two major suprafamilial taxa, Iguania and Scleroglossa, consisting of carnivorous species characterized by two major foraging modes, ambush and active, and of herbivores and omnivores. PETF is absent in the two families of carnivorous iguanian lizards studied that are ambush foragers but present in three families of scleroglossan lizards that are active foragers. However, PETF is absent in the two species studied in a scleroglossan family, Gekkonidae, which forages by ambush, and present in an iguanian herbivore, as reported herein. We propose that the presence or absence of PETF, in addition to its phylogenetic determinants, is adaptively adjusted to foraging mode.

Cephalic phase of colonic pressure response to food.

A cephalic phase of colonic pressure response to food was sought in five normal subjects (mean age (22.6) years, 22-24), studied on six separate occasions by recording intraluminal pressures in the unprepared sigmoid colon. Gastric acid secretion was measured simultaneously by continuous aspiration through a nasogastric tube. After a 60 minute basal period, one of five 30 minute food related cephalic stimuli, or a control stimulus was given in random order; records were continued for a further 120 minutes. The cephalic stimuli were: food discussion, sight and smell of food without taste, smell of food without sight or taste, sight of food without smell or taste, and modified sham feeding; the control stimulus was a discussion of neutral topics. Colonic pressures were expressed as study segment activity index (area under curve, mm Hg.min) derived by fully automated computer analysis. Gastric acid output was expressed as mmol/30 min. Food discussion significantly (p < 0.02, Wilcoxon's rank sum test) increased colonic pressure activity compared with control or basal activity. Smell of food without sight or taste also significantly (p < 0.03) increased the colonic pressure activity compared with control and basal periods. Sham feeding and sight and smell of food without taste significantly (p < 0.02 and p < 0.03) increased colonic pressures compared with control but not basal activity. The increase in colonic activity after sight of food without smell or taste was not significantly different from control or basal activity (p = 0.44 and p = 0.34). Food discussion was the strongest colonic stimulus tested. Food discussion and sham feeding significantly (p<0.02) stimulated gastric acid output above control and basal values. Sight and smell of food without taste significantly (p<0.02) increased acid output above basal. Smell of food without sight or taste and sight of food without smell or taste did not significantly (p=0.06, p=0.34) increase acid output. In contrast with the effect on colonic pressures, sham feeding was the best stimulus of acid output. Increased colonic pressure activity after food discussion correlated significantly (r=0.45, p<0.02) with gastric acid output. There was no correlation (r=-0.1, p>0.5) between colonic pressure activity and gastric acid output in the control study. These data show that there is a cephalic phase of the colonic response to food.

Hunger and appetite during visual perception of food in eating disorders

SummaryNineteen different slides of food items and their effects on appetite and hunger as rated on visual analogue scales were investigated in 20 bulimics and 9 anorexics (DSM-III-R) at the onset and after 8 weeks of behavioral hospital treatment; 9 controls were examined at the maximum of weight loss during a diet and at normal weight. At the onset of treatment appetite ratings were significantly lower in patients than in dieting controls. In anorexics and bulimics appetite ratings increased significantly during treatment. The sight of food did not increase reported hunger in bulimics but did so in controls. Appetite ratings, however, were significantly increased by the sight of food in bulimics as well as in controls. Despite the small sample size, it may be concluded that dieting and weight loss have different psychological implications in healthy controls and in patients with eating disorders, that dieting rather than weight per se influences appetite and that differences in hunger responsiveness to the sight of food in anorexics and bulimics seem likely.

Topographic distribution of modality-specific amygdalar neurons in alert monkey

Neuronal activity in the amygdala (AM) was recorded from alert monkeys during performance of tasks that led to presentation of rewarding or aversive stimuli. The tasks had 3 phases: (1) discrimination (visual, auditory), (2) operant response (bar pressing), and (3) ingestion (reward) or avoidance (aversion). Neuronal activity was analyzed and compared during each of these phases. Of 585 AM neurons tested, 312 (53.3%) responded to at least one stimulus in one or more of 5 major groups: vision related, audition related, ingestion related, multimodal, and selective. Forty neurons (6.8%) in the anterior dorsolateral capsule of the basolateral nuclei responded exclusively to visual stimuli (vision related). Twenty-six neurons (4.4%) further posterior in the basolateral group responded only to auditory stimuli (audition related). During ingestion an additional 41 neurons (7.0%) increased their activity (ingestion related). These were in the corticomedial group and at the boundaries between the nuclei of the basolateral group. Of these, 27 responded only in the ingestion phase, 11 during ingestion and at the sight of food, and 3 during ingestion and to certain sounds. Throughout the AM other neurons (n = 117, 20.0%) responded to visual, auditory, and somesthetic stimuli and, when tested, to involuntary ingestion of liquid (multimodal). Of these, 40 responded transiently (phasic; 36 excited, 4 inhibited). The remaining 77 maintained their altered activity into the subsequent phases of the task (tonic; 69 excited, 8 inhibited). In each of these 4 categories, most cells were activated primarily by novel or unfamiliar stimuli, and their responses habituated during repeated stimulation. A small number of cells in the basolateral and the basomedial nuclei (n = 14, 2.4%) were highly selective in that they responded specifically to one biologically significant object or sound more than to any other stimuli (selective). Some of these neurons responded to both sight and ingestion of a specific food. In summary, most AM neurons responded vigorously to novel stimuli, and some of the neurons had multimodal responsiveness. These results suggest the AM is related to processing of new environmental stimuli and to those cross-modal association.

Effect of denervation on initiation and coordination of gastroduodenal motility in turkeys.

The effect of total extrinsic denervation of the stomach on the rhythmicity and coordination of the gastroduodenal cycle was determined in domestic turkeys. The vagus and two gastric branches of the sympathetic nerve were sectioned at the level of the glandular stomach. Motilities of the glandular stomach, proximal duodenum, and caudal thin muscle of the muscular stomach were monitored via implanted strain gauge transducers for 1 h every other day. Denervation had no significant effect on initiation of contractions or frequency of gastric contractions in fed birds, but fasted birds whose stomachs were extrinsically denervated exhibited significantly slower contractions than controls. In addition, denervation uncoupled the coordination of the duodenal and gastric contractions in the gastroduodenal cycle. Moreover, birds with extrinsically denervated stomachs exhibited a cephalic phase of gastric motility that was significantly delayed in onset compared with controls. These results suggest the existence of both a neural and endocrine component in the avian gastric response to the sight of food. Extrinsic input seems to be an important modulator of gastric motility in birds and is essential for the normal coordination of the gastroduodenal contraction cycle.

How closely do circulating blood glucose levels reflect feeding state in fowls?

1. 1. Amounts of food eaten in 30 min, by fasted-refed immature hens, were not correlated with plasma glucose levels before feeding, or with increases in glucose after feeding. 2. 2. When previously fasted birds were given 0, 5, 10,15 or 20 g food to eat, their plasma glucose increased by similar amounts with 10, 15 and 20 g, by slightly less with 5g, and hardly at all with 0g. 3. 3. When food was removed from free-feeding birds, their plasma glucose levels declined slightly in 2 hr and then remained steady. They declined markedly further overnight, but recovered to a level higher than before deprivation when 10 g food was provided. 4. 4. Four hours darkness during normal daytime had no effect on plasma glucose in fasted-refed birds, but sight of food and presentation of an empty food pan caused slight increases in glucose in 24-hr fasted birds. 5. 5. It is concluded that blood glucose in fowls fluctuates around several “typical” levels, but that there is also much variation between and within birds. Direct (absorbed) and indirect (thermogenic) consequences of feeding probably both contribute to fluctuations in glucose, and these seem more likely to influence regulation of food intake in the longer-term rather than the short-term.

Cephalic control of avian gastric secretion

Abstract 1. 1. Turkeys, chickens, great-horned owls and red-tailed hawks were surgically fitted with a cannula in either the glandular stomach (fowl) or muscular stomach (raptors) to permit collection of gastric secretions. 2. 2. After 24 hr of fasting, secretions were collected during three successive periods of no food in sight, food in sight but unavailable and food available. 3. 3. Neither gastric secretory volume nor pH was influenced by the sight of food for domestic turkeys, floor-raised domestic chickens, or red-tailed hawks. 4. 4. Gastric secretory volume increased significantly from 1.08 to 1.47 ml/kg (45-min collection period) when food was in view but unavailable for great-horned owls. 5. 5. Increases in volume and pH which occurred when food was consumed were accounted for by ingestion of food and water, or fluids in the meat eaten by the raptors.

Reduced adrenocortical function and increased thyroid function in fasted and refed chickens.

The deprivation of food for 48 h markedly increased (P&lt; 0·001) the corticosterone concentration in the plasma of 7- to 8-week-old chickens. When fasted birds were refed for 2 min or 5 s the corticosterone concentration fell to the level in fed birds within 30 min of refeeding. In fasted and refed birds the plasma corticosterone concentration remained lowered for at least 150 min after a 2-min period of refeeding, whereas in birds refed for 5 s the concentration had increased within 120 min to that in fasted birds. When fasted birds were refed 1, 5, 15 or 30 g diet the corticosterone level was again markedly reduced (P&lt; 0·001) within 45 min of refeeding. The magnitude of this post-feeding decline was unrelated to the amount of food eaten, although its duration was; the level in birds refed 1, 5 or 15 g food increasing to that in fasted birds within 90, 135 and 225 min respectively. The corticosterone level in birds refed 30 g diet remained reduced for at least 225 min but increased to that in fasted birds 24 h after refeeding. The initial decline in the corticosterone concentration was unrelated to the consumption of food, since a similar reduction in the corticosterone level was observed in fasted birds which were given the sight of food but prevented from eating it by Perspex lids attached to the food troughs. This initial decline in the corticosterone level was not a result of stress, as it did not occur in fasted control birds. These results suggest that the adrenocortical changes in fasted and refed birds is initially mediated by a conditioned neural stimulus (reinforcement) and is maintained as a result of peripheral metabolic effects of ingested food. In fasted chickens the concentration of plasma tri-iodothyronine (T3) was greatly reduced (P&lt;0·001) in comparison with fed birds. When fasted birds were refed for 2 min or with 5, 15 or 30 g diet, the level of plasma T3 was increased (P &lt; 0·05) 90 min after refeeding although not to the level in birds which had free access to food. The magnitude and duration of this increase was related to the amount of food consumed and was not observed in birds refed for 5 s or with 1 g food or in fasted birds given sight of but not access to food.

Experiments on attracting sheep to move along a laneway. II. Auditory stimuli

The use of auditory stimuli as attractants to sheep moving along narrow laneways (races) was examined. Sheep vocalizations were recorded in four situations: (1) isolation of one sheep from the rest of the flock; (2) the sight of food when hungry; (3) a ewe separated from her lamb; (4) a lamb separated from its mother. The effect of these vocalizations on sheep movement along a race was observed while the calls were played back in the race. The effect of the type of call, the individual sheep making the call and the rate of calling was examined. Although none of the calls was more or less attractive than an absence of calls (silence), the first sheep moved faster towards isolation and food calls than towards ewe and lamb calls. The lamb calls particularly inhibited movement of the first sheep, although the rate of movement of the whole flock was not affected by any of the vocalizations. Sheep showed no preference for moving towards either a sheep call or silence in a Y-maze. Although calls may have different effects on sheep movement, there appears to be no practical advantage in using sheep calls to attract sheep to move along a race.

Monkey lateral hypothalamic neuron response to sight of food, and during bar press and ingestion

Unit activity of 144 lateral hypothalamus (LHA) neurons was analyzed in monkey during bar pressing feeding behavior. Eighteen neurons responded only when the animal saw food, and 23 responded only during ingestion of food. Ten responded at both the sight of food and throughout the bar pressing and ingestion periods, even in high fixed ratio schedules. Three neurons responded, not at the sight of food, but at the sight of non-food. Nineteen out of a total of 54 of the above responding neurons were studied for response to differences between food and non-food. Eight responded similarly at the sight of both food and non-food, while 11 responded differently. Responses during the ingestion period were strong and lasted longer than 5–10 sec. The data indicate that some LHA neurons are involved in the discrimination of food, the drive to obtain it and the perception of reward.

Possible links between hypothalamus and substantia nigra in the rat

A possible neuronal link between the lateral hypothalamus (LH) and substantia nigra (SN) is revealed by tracing methods utilizing either orthograde or retrograde axonal transport. Retrograde transport of horseradish peroxidase suggests that neurones in the paraventricular nucleus of the hypothalamus may also project to the SN. These results suggest a role for SN in ingestive behaviours since, in hungry monkeys, cells in the LH are known to respond to the sight of food and since vasopressin-secreting cells in the hypothalamus respond to dehydration.

Role of the lateral hypothalamus and the amygdala in feeding behavior

Unit activities of the lateral hypothalamic area (LHA) and amygdala (AM) were recorded during bar pressing feeding behavior in monkeys. Out of 103 LHA neurons tested, 9 decreased its firing selectively at the sight of food and not to non-food, and most of this initial response continued all through the subsequent bar pressing period. The firing decreased again after the animal put food into mouth. The discrimination ratio of food was calculated to be 54% in the LHA. Even in the AM, some neurons responded uniquely to food, and not to non-food. This differential response became more clear in the repeated subsequent trials. The discrimination ratio of food was calculated to be 25% to 44%. Although almost all of the initial responses were not maintained during the bar pressing period, 22 neurons (18% of tested) increased firing at the reward period in the AM. These data suggest that the LHA is deeply involved in the bar pressing feeding behavior all through the perception of food, the driving mechanism to obtain food, and the final reward response, while the AM seems to be concerned in some perception and reward response.

The latency of activation of neurones in the lateral hypothalamus and substantia innominata during feeding in the monkey

To investigate whether the responses of neurones in the lateral hypothalamus and substantia innominata associated with the sight of food could control the responses of the hungry monkey to the food, the latency of activation of these neurones by food was measured. It was found that when an electromagnetically operated wide-aperture shutter opened to reveal food or non-food objects, these hypothalamic neurones responded with a latency of 150–200 msec to the food objects, and did not respond to the non-food objects. To measure the latency of the monkey's responses to the food, a visual discrimination task was set in which the monkey could lick a tube to obtain fruit juice if a food-related visual stimulus was shown, but obtained hypertonic saline, which was aversive, if a different visual stimulus was shown. In this situation the typical latencies of the neuronal responses to the food were 150–200 msec, of the lick responses 350–400 msec. and of the EMG activity associated with these lick responses 250–400 msec. Thus the responses of these hypothalamic neurones precede the monkey's responses to the food, and could mediate the feeding and other responses of the animal to the food. It was also shown that a different population of hypothalamic neurones with responses associated with the sight of aversive visual stimuli had response latencies of 150–200 msec.

A Cephalic Influence on Gastric Motility upon Seeing Food in Domestic Turkeys (Melagris gallopavo), Great-Horned Owls (Bubo virginianus) and Red-Tailed Hawks (Buteo jamaicensis)

Strain gage transducers were permanently implanted on the muscular stomachs of 13 turkeys, 3 great-horned owls and 2 red-tailed hawks to monitor gastric motility before, during and after eating. Following fasting, the sight of food resulted in significant increases in gastric contractile activity in all three species. Gastric motility further increased when the birds were allowed to eat. In raptors, however, a brief interruption in gastric motility occurred immediately after eating. This is apparently analogous to receptive relaxation which occurs in the stomach of mammals.

Hypothalamic neuronal responses associated with the sight of food

Neurones in the lateral hypothalamic region are described which alter their firing rates when a monkey looks at food. The units responsed when the monkey looked at different types of food, but not at non-food objects or simple visual stimuli. The units did not respond in relation to motor movements, intense arousal, nor when a salient aversive stimulus was shown, nor in relation to eye movements, and were thus shown to be different from units in the globus pallidus which did respond in some of these control tests. The neurones did not respond to olfactory stimuli and did not respond if the animal ate in the dark. Because of these findings it is suggested that the activity of these hypothalamic neurones is associated with the sight of food. It is of interest that these neurones which respond when food is shown to a hungry animal are found in a region thought to be involved in the control of feeding.

The Sight of Food

The Sight of Food

Enhanced Learning of a Position-Habit with Secondary Reinforcement for the Wrong Response

It has recently been suggested that while the concept of secondary reinforcement is very frequently used, direct supporting evidence is surprisingly sparse and equivocal.l Much of the relevant evidence is concerned with the observation that a response which is followed by a secondary reinforcing stimulus extinguishes more slowly than a response with no such reinforcement, but this phenomenon can be explained at least as effectively in terms of discrimination.2 Direct evidence of the effect of secondary reinforcement on acquisition is less common, and such effects as have been demonstrated are rarely as marked as the theory would predict.3 Once again the results are open to an interpretation in terms of discrimination. The present study aims to examine a situation in which the sight of food would be expected to strengthen the wrong R if it acts as a simple secondary reinforcement, while aiding the correct R if it acts as a cue to the location of rewzd.

THE PHYSIOLOGY OF THE GASTRIC HUNGER CONTRACTIONS IN THE JAVANESE MONKEY.1

1. The motility and tonus of the empty stomach of the monkey is practically identical with that of the empty stomach of man.2. Substances introduced directly into the stomach (water, 1 per cent. sodium carbonate, and 0·5 per cent. hydrochloric acid) produce gastric inhibition in proportion to the degree of their potency.3. Very small amounts of food given to animals exhibit no inhibitory influence on the movements of the empty stomach; in larger quantities definite inhibitory effects result.4. The sight of food, when in sufficient amounts, may also lead to an inhibition (psychic inhibition) of the motor activity and tonus of the stomach.5. The same mechanism is probably involved in the inhibition of the movements of the empty stomach that is concerned in the inhibition of the movements of digestion.6. Stimuli when applied to certain sensory surfaces of the body of the animal, such as the pad of the foot, may produce decided inhibitory effects.