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PubMed1969

The smallest time difference the eyes can detect with sweep- ing stimulation.

Experiments in hearing showed that a time difference of 0.1 msec between the stimulation of the left and right ear by a similar click was enough to be recognized as a spatial shift of the integrated sound perception. Similar phenomena were obtained for taste stimulation on both sides of the tongue or with an odorous substance introduced to both nostrils. No similar phenomenon was obtained in binocular vision, when a short time difference between the stimulation of both eyes was introduced and the location of the fused image was observed. It was found that this peculiarity for vision could be eliminated when the stimuli for vision were made more identical to the stimuli used for the other sense organs, practically most of which were sweeping stimuli. Sweeping light stimuli with time differences of 0.1 msec between both eyes could be detected as spatial shifts with the same precision as for the other senses. This widens the expected similarities between the different sense organs.

Functional Laterality↗
PubMed2001

Activation of prefrontal cortex and anterior thalamus in alcoholic subjects on exposure to alcohol-specific cues.

BACKGROUND: Functional imaging studies have recently demonstrated that specific brain regions become active in cocaine addicts when they are exposed to cocaine stimuli. To test whether there are regional brain activity differences during alcohol cue exposure between alcoholic subjects and social drinkers, we designed a functional magnetic resonance imaging (fMRI) protocol involving alcohol-specific cues. METHODS: Ten non-treatment-seeking adult alcoholic subjects (2 women) (mean [SD] age, 29.9 [9.9] years) as well as 10 healthy social drinking controls of similar age (2 women) (mean [SD] age, 29.4 [8.9] years) were recruited, screened, and scanned. In the 1.5-T magnetic resonance imaging scanner, subjects were serially rated for alcohol craving before and after a sip of alcohol, and after a 9-minute randomized presentation of pictures of alcoholic beverages, control nonalcoholic beverages, and 2 different visual control tasks. During picture presentation, changes in regional brain activity were measured with the blood oxygen level-dependent technique. RESULTS: Alcoholic subjects, compared with the social drinking subjects, reported higher overall craving ratings for alcohol. After a sip of alcohol, while viewing alcohol cues compared with viewing other beverage cues, only the alcoholic subjects had increased activity in the left dorsolateral prefrontal cortex and the anterior thalamus. The social drinkers exhibited specific activation only while viewing the control beverage pictures. CONCLUSIONS: When exposed to alcohol cues, alcoholic subjects have increased brain activity in the prefrontal cortex and anterior thalamus-brain regions associated with emotion regulation, attention, and appetitive behavior.

Alcohol Drinking↗
PubMed1992

Monkey hippocampal neuron responses to complex sensory stimulation during object discrimination.

The purpose of this study was to investigate, during the performance of an object discrimination task, responses of neurons in the monkey hippocampal formation to the sight of several objects that have biological meaning, and compare these responses with those of amygdalar neurons studied previously using the same task. Neuronal activity in the hippocampal formation of conscious monkeys was recorded during performance of a task that led to presentation of familiar rewarding, familiar aversive, or unfamiliar objects. Of 864 neurons recorded in the hippocampal formation and adjacent cortices, 160 (18.5%) responded to the sight of a certain object(s). Responses to the sight of different kinds of objects were analyzed in detail. Nondifferential neurons (n = 73) responded to different objects with no significant difference in response magnitudes, and differential neurons (n = 87) responded to different objects with different response magnitudes. Of the differential neurons, 23 responded more strongly to rewarding objects than to other objects (rewarding-object-dominant neurons), but the magnitude of responses to objects did not necessarily correlates with the order of preferences to the objects as determined from observation of animal behavior. Aversive-object-dominant neurons (n = 13) responded more to aversive objects than to other objects. Unfamiliar-object-dominant neurons (n = 7) responded more to unfamiliar objects than to familiar objects. Selective neurons (n = 10) responded selectively to only one object or one category of objects. Fourteen of the rewarding- or averse-object-dominant neurons were tested in extinction or reversal trials. In 12 of 14 neurons, responses to a rewarding or aversive object did not change, or slightly weakened, in extinction or reversal trials. The results suggest the following. (1) Responses of rewarding- or aversive-object-dominant neurons may be involved in object-reward or object-aversion association. However, responses of many of these neurons might reflect past inputs to reinforcement rather than extant emotional processing. (2) Responses of unfamiliar-object-dominant neurons may be involved in recognition of objects based on their familiar or unfamiliar aspects. These results are further discussed and compared with responsiveness of amygdalar neurons.

Acoustic Stimulation↗
PubMed1998

Is pleasantness of biscuits and cakes related to their actual or to their perceived sugar and fat contents?

Perceptions of sugar, fat and moisture contents, as well as their influences on pleasantness were investigated in commercial foods. One-hundred-and-two-normal-weight men rated the "pleasantness", "flavour intensity", "moisture", "sweetness" and "fatness" of 39 different biscuits and cakes. Sugar content was accurately perceived up to a maximum content of about 33% weight/weight. The perception of fat content was less accurate and depended on both fat and sugar contents. High sugar contents seemed to decrease perception of fatness. Pleasantness was influenced mainly by sugar content and less by fat content. Pleasantness was better predicted by rated contents than by actual contents; it was even better predicted by the overall flavour intensity. Preferences for high fat stimuli did not appear to be based on conscious perception of their fat content. We conclude that the classical results obtained with simple experimental stimuli remain valid, as a first approximation, for commercial biscuits and cakes, despite their complex sensory characteristics.

Adolescent↗
PubMed1992

Sweetness does not habituate during a sip-and-spit experiment.

In gravitational flow studies, the estimated saltiness of a NaCl/sucrose mixture increases after repetitive stimulations with sucrose. This increment is hypothesized to be the consequence of successive contrast and suppression release. According to the successive contrast hypothesis, the saltiness of the mixture percept is overestimated because its salty taste stands out against the preceding sweet tastes. The release of saltiness from suppression is supposed to originate from habituation to sweet stimuli. In the present study, the saltiness of a NaCl/sucrose mixture was judged after repetitive stimulations with sucrose using a sip-and-spit procedure. The increment in saltiness estimates after repeated stimulations with sucrose could be fully accounted for by successive contrast. No suppression release was observed. Differences in experimental procedure (the degree of experimental control, the subjects' arousal level, the variation in the proximal stimuli, the area of the tongue stimulated, and the subjective intensities of the habituating stimuli) that may affect the rate of habituation, are suggested as potential sources of the differences between the gravitational flow studies and the present one.

Adolescent↗
PubMed2006

Sensory correlation of glucose levels in a starch-based semi-solid model system before and after alpha-amylase breakdown.

In this study a diabetic glucose monitor was used to measure the glucose content of 40 model vanilla custard desserts, these were compared with sensory ratings from a trained quantitative descriptive analysis panel. Stimuli varied in starch type, concentration and homogenisation but had identical sugar, flavour and fat contents. Despite this, mean sensory ratings of sweetness varied from 21 to 43 on a 100-point scale. Glucose levels in the stimuli were measured, in vitro, before and after the addition of 0.1% whole human saliva to the product. In all cases glucose concentration increased after the addition of saliva as starch was converted to glucose. There were highly significant correlations of some odour, flavour, mouth feel and after-feel attributes with glucose concentration. The correlation of sweet flavour with glucose concentration was higher in unmodified stimuli than in stimuli with added saliva, suggesting that sweetness is perceived soon after ingestion. Additional glucose produced through starch breakdown appeared to have a relatively small impact on the sensory scores of the stimuli.

Adult↗
PubMed2006

Deficits across multiple cognitive domains in a subset of aged Fischer 344 rats.

Rodent models of cognitive aging routinely use spatial performance on the water maze to characterize medial temporal lobe integrity. Water maze performance is dependent upon this system and, as in the aged human population, individual differences in learning abilities are reliably observed among spatially characterized aged rats. However, unlike human aging in which cognitive deficits rarely occur in isolation, few non-spatial learning deficits have been identified in association with spatial impairment among aged rats. In this study, a subset of male aged Fischer 344 rats was impaired both in water maze and odor discrimination tasks, whereas other aged cohorts performed on par with young adult rats in both settings. The odor discrimination learning deficits were reliable across multiple problems. Moreover, these deficits were not a consequence of anosmia and were specific to olfactory learning, as cognitively impaired aged rats performed normally on an analogous non-olfactory discrimination task. These are among the first data to describe an aging model in which individual variability among aged rat cognition occurs across two independent behavioral domains.

Aging↗
PubMed2006

Modification of spatial recognition memory and object discrimination after chronic administration of haloperidol, amitriptyline, sodium valproate or olanzapine in normal and anhedonic rats.

In the present study we have investigated the effects of a chronic administration of olanzapine (Ola) on visual and spatial memory in normal and anhedonic rats. The effects of Ola have been compared to those of the typical antipsychotic Hal, the tricyclic antidepressant amitriptyline (Ami), and the mood stabilizer VPA. Anhedonia (assessed by reduction of sucrose preference) was induced by administration of a chronic mild stress (CMS) protocol, in which rats were exposed sequentially, over a period of 4 wk, to a variety of unpredictable mild stressors. The spatial memory was evaluated by testing the ability of the rats to discriminate a familiar vs. a novel environment, while the visual memory was assessed by testing the ability of the rats to discriminate familiar vs. novel objects. In CMS-free rats, VPA (5 or 30 mg/kg.d), Ola (0.02 or 0.1 mg/kg.d), Ami (2 mg/kg.d) and Hal (0.2 mg/kg.d) caused no detectable modifications of visual memory, whereas VPA (5 mg/kg.d), Ami (2 mg/kg.d) and Ola (0.02 mg/kg.d) did not modify spatial memory performance. In our experimental conditions, the administration of the CMS protocol caused an impairment of both visual and spatial memory. The chronic treatment of anhedonic rats with Ola (0.02 mg/kg.d) or Ami (2 mg/kg.d) prevented, at least in part, the stress-induced impairment of visuospatial performance. In conclusion, the results of the present preclinical study seem to indicate that the chronic administration of low doses of Ola or Ami has the potential to lead to substantial cognitive benefits in depressed patients.

Amitriptyline↗
PubMed2006

Intensity and persistence profiles of flavor compounds in synthetic solutions. Simple model for explaining the intensity and persistence of their aftersmell.

Hydroalcoholic solutions containing a single aroma-active compound were evaluated by a sensory panel to determine the difference between ortho and retronasal odor intensities (DeltaI(ro)), buccal savoring, and aftersmell duration. Eight compounds were used. Buccal perception seems to be just a physiologically restricted form of retronasal perception. DeltaI(ro) values were dependent on the panel, although results from the two panels were significantly correlated. Such differences and the aftersmell persistence were also significantly correlated with different physicochemical parameters related to volatility. A simple model to explain such dependence is proposed. The model considers the mouth-throat system as a perfect mixing tank with a finite amount of odorants being progressively diluted by swallowing and purging (both taken as continuous processes). Retronasal intensity is modeled from the odor properties of the liquid in such a tank calculated from orthonasal odor intensity versus concentration (I/log C) curves. The model explains successfully experimental results and has also been successfully applied to instrumental data from other authors.

Alcohols↗
PubMed1979

Parotid and whole-mouth secretion in response to viewing, handling, and sniffing food.

There was no significant change in flow rates of parotid saliva in nineteen of twenty subjects while they viewed photographs of lemons, or in fourteen of twenty subjects while they cut lemons in a glove box. Neither parotid nor whole-mouth secretion changed from baseline when subjects viewed fresh lemons and lemonade presented in a plastic box. Further, no significant changes in whole-mouth secretion rates were observed when subjects viewed photographs of two appetizing foods, or of fresh doughnuts in a plastic box, even though subjects knew they could eat the doughnuts after the experiment. In most cases, sniffing of the lemons or of the doughnuts resulted in increased flow rates. Subjects demonstrated large differences in their patterns of affective responses to full-strength and diluted lemon juice, which were independent of salivary flow. In the absence of olfactory or tactile stimulations, few subjects altered parotid or whole-mouth secretion rates in response to viewing food or photographs of food. A reevaluation of findings on 'psychic' stimulation of saliva may be in order to ascertain the role of olfactory, tactile, and even trigeminal clues in salivary response to food stimuli.

Citrates↗
PubMed2002

Failure to reduce short-term appetite following alcohol is independent of beliefs about the presence of alcohol.

Previously, it has been reported that energy consumed as alcohol prior to lunch does not result in subsequent reductions in voluntary food intake, and in some situations alcohol can increase subsequent appetite. The present study extends these findings by examining the effects of beliefs about alcohol content. Eighteen unrestrained men ate lunch 20 min after a preload of either water, an alcoholic beer or a non-alcoholic beer matched for energy content. Food intake was significantly less following the non-alcoholic beer than after alcohol or water, but when preload energy was included subjects had a higher overall energy intake on the day they consumed alcohol compared with both water and no-alcohol conditions. There were no significant differences in hunger or fullness ratings following the three drinks before or after the test meal, but the specific relationship between rated hunger and intake within the test meal was altered by the drink manipulation. The rate at which hunger decreased, and fullness increased, was slower after alcohol than after water or no-alcohol. The drinks did not alter the pleasantness of the test meal or increase hunger at the start of eating. When contrasted with previous work, these data confirm that alcohol consumed before lunch fails to reduce subsequent food intake, but also suggests that changes in rated appetite are influenced by beliefs about alcohol content.

Adult↗
PubMed1998

PTC and PROP behave differently in tests of discrimination from their solvents.

Better discrimination was possible between phenylthiocarbamide (PTC) solutions and the pure solvent when the solvent was a tasteless low-concentration NaCl solution to which the subject had adapted than when the solvent was purified water. The reverse was true for 6-n-propylthiouracil (PROP). The differences in discrimination for PROP and PTC in the different solvents were caused by differences in the intensity and persistence of aftertastes, rather than a more intense perception of the PTC and PROP tastes per se. This has consequences for traditional approaches to measuring taste sensitivity, as well as indicating that PTC and PROP are not necessarily equivalent indicators of 'taster' versus 'non-taster' status.

Adult↗
PubMed2002

The effect of viscosity on the perception of flavour.

A trained sensory panel assessed flavour and sweetness intensity in solutions containing varying concentrations of hydroxy propyl methylcellulose (HPMC), sugar and flavour volatile. The flavour and sweetness of the viscous solutions were rated using magnitude estimation with a controlled modulus. In addition, the concentration of volatile released on the breath was measured using MS Nose. For low concentrations of HPMC (<0.5 g/100 g), perceived flavour intensity remained the same; however, a steady decrease was noted at higher concentrations (>0.6 g/100 g). The change in perceived intensity occurred at the point of random coil overlap (c(*)) for this hydrocolloid. The perceived sweetness of the solution showed a similar pattern with increasing HPMC concentration, although the inflection at c(*) was not so obvious. Despite the change in perceived flavour intensity, the actual concentration of volatile measured on the breath was not affected by the change in HPMC concentration. Low-order polynomial models were produced to describe perceived flavour intensity and sweetness in viscous solutions containing HPMC and potential explanations for the changes in perception are discussed.

Benzaldehydes↗