The ontogeny of the peck response in Gallus gallus: constraints on a model system of memory.
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Age Factors↗
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Effect of addition of grit made of crude and expanded amaranth seeds on the quality of canned meat.
Grit made of crude and expanded amaranth seeds was added to meat-fat batter in order to determine its effect on its quality. Amaranthus cruentus seeds were expanded by the nonpressure method and graded by density (degree of expansion) into three fractions: 341, 208 and 135 kg/m3; crude seed density was 800 kg/m3. Then the seeds were ground to a homogeneous mass with granulation of 0.8 mm. The water-holding capacity and viscosity of grit made of crude and expanded seeds were determined. Class II pork was used for the production of meat-fat batter. Cooking losses were determined in model meat-fat batter, pasteurized and sterilized cans. The texture and color parameters of canned meat were also determined, and a taste-panel evaluation was made. It was found that expanded seed grit was characterized by worse hydration and gelling properties than crude seed grit. Grit made of crude amaranth seeds had a positive effect on the water-holding capacity of stuffing and allowed to reduce the cooking losses in cans. Better water-holding capacity resulted in an improvement in the tenderness, juiciness and taste of canned meat. Its quality deteriorated when large amounts of highly-expanded seed grit were used.
Amaranthus↗
Enhancement of long-term memory retention by Colostrinin in one-day-old chicks trained on a weak passive avoidance learning paradigm.
Colostrinin (CLN) is a biologically active proline-rich polypeptide which has therapeutic potential for the alleviation of memory deficits in age-related dementias in a number of human conditions, particularly Alzheimer's disease. To examine the efficacy of CLN in other species, day-old domestic chicks were used as a model system to study its effects on retention of memory for a single one-trial learning paradigm--avoidance of a bitter-tasting substance (methylanthranilate, MeA). Birds were presented with a bead coated with either a dilute (10%) solution of MeA or a bead coated with 100% MeA. Those trained on 100% MeA avoided pecking at a similar but dry bead 24 h later, thereby demonstrating long-term memory whereas chicks trained on the 10% solution pecked the bead at 24 h, indicating lack of long term memory for the task. However, when CLN was injected (i.c.) into a region known to be important in memory formation, the mesopallium intermediomediale (IMM), prior to training with 10% MeA, chicks exhibited strong memory retention at 24 h, similar to those trained on 100% MeA. Control chicks trained on 10% MeA but injected i.c. with a 10% saline solution did not show improvement in memory retention. Intraperitoneal (i.p.) injections of CLN were as effective as the i.c. route. These data extend the known efficacy of CLN from mammals demonstrating its widespread efficacy as a cognitive enhancer.
Animals↗
Isotropic-sequence-order learning in a closed-loop behavioural system.
The simplest form of sensor-motor control is obtained with a reflex. In this case the reflex can be interpreted as part of a closed-loop control paradigm which measures a sensor input and generates a motor reaction as soon as the sensor signal deviates from its desired (resting) state. This is a typical case of feedback control. However, reflex reactions are tardy, because they occur always only after a (for example, unpleasant) reflex-eliciting sensor event. This defines an objective problem for an organism which can only be avoided if the corresponding motor reaction is generated earlier. The goal of this study is to design a closed-loop control situation where temporal-sequence learning supersedes a tardy reflex reaction with a proactive anticipatory action. We achieve this by employing a second, earlier-occurring and causally coupled sensor event. An appropriate motor reaction to this early event prevents triggering of the original, primary reflex. Such causally coupled sensor events are common for animals, for example when smell predicts taste or when heat radiation precedes pain. We show that trying to achieve anticipatory control is a fundamentally different goal from trying to model a classical conditioning paradigm, which is an open-loop condition. To this end, we use a novel learning rule for temporal-sequence learning called isotropic-sequence-order (ISO) learning, which performs a confounded correlation between the primary sensor signal associated to the reflex and a predictive, earlier-occurring sensor input: this way the system learns the relation between the primary reflex and the earlier sensor input in order to create an earlier-occurring motor reaction. As a consequence of learning, the primary reflex will not be triggered any more, thereby permanently remaining in its desired resting state. In a robot application, we demonstrate that ISO learning can successfully solve the classical obstacle-avoidance task by learning to correlate a built-in reflex behaviour (retraction after touching) with earlier arising signals from range finders (before touching). Finally, we show that avoidance and attraction tasks can be combined in the same agent.
Adaptation, Physiological↗
Genomic structure of swine taste receptor family 1 member 3, TAS1R3, and its expression in tissues.
Taste receptor family 1 member 3, TAS1R3, is shown to be involved in sweet and umami tastes in mouse, and the nucleotide sequence of the gene has been reported in rat, gorilla, and human. Pigs are frequently used as models for human diseases, and are also considered to be source animals for xenotransplantation to humans due to their anatomical and physiological similarities to humans. Therefore, in the present study, the genomic structure of the swine TAS1R3 gene was determined, and TAS1R3 expression was studied in various swine tissues. The gene was shown to reside on swine chromosome 6q22-->q23, from which three types of mRNAs were generated: 3,752 bp derived from six exons in tongue, 3,704 bp from six exons and 3,630 bp from seven exons in testis. The 6 exons/5 introns were structurally similar to those of humans and mice, but the 7 exons/6 introns structure of TAS1R3 was first observed in swine. High expressions of TAS1R3 were revealed in tongue, kidney, and testis by real-time PCR. The expression profile of the tissues except for kidney was similar to that of mouse. When in situ hybridization using an RNA probe for TAS1R3 was performed on swine tongue and testis tissues, TAS1R3 expressions were revealed in tongue circumvallate papillae, fungiform papillae, mucosal epithelium, follicular B lymphocytes, lymphocytes in submucosal tissues of lingual tonsil, and spermatogenic cells. Using peripheral mature B lymphocytes, the expression of TAS1R3 in B lymphocytes was further confirmed by real-time PCR and sequencing of the real-time PCR product.
Animals↗
Bitter and sweet/umami taste receptors with differently evolutionary pathways.
In this study,we investigated the evolutionary pathways of bitter, sweet and umami receptors using bioinformatic and phylogenetic analyses. Our results showed that the distantly evolutionary relationship between bitter and sweet/umami receptors. Our results also showed that bitter and sweet/umami receptors have differently evolutionary pathways,suggesting that the different evolutionary pathways may resulte in the differences of these three receptors in function.
Amino Acid Sequence↗
Structural relationships of sugars to taste.
Chemical modification of sugars and their simple analogues indicates that these types of compound are almost always sweet, bitter, or bitter/sweet; hence, the two basic tastes may be intimately associated features of the same molecule. Stepwise modification at each chiral center around the sugar ring allows the sapid functions in these molecules to be mapped and leads to the inescapable conclusion that sugar molecules may be "polarized" on taste bud receptors, so that one end of the molecule elicits sweetness and the other bitterness. However, more extensive chemical modification evidently causes the molecule to realign itself in entirely different ways on the receptor. In most oligosaccharides only one sugar residue is likely to bind to the taste receptor, and this is probably a nonreducing end group, because the anomeric center of glucopyranose types of structure does not appear to affect sweetness. Sweetness depresses bitterness and bitterness depresses sweetness. Hence, it is not possible to make structural comparisons between analogues without correcting for these effects. However, some semiquantitative studies have established the value of current hydrogen bond theories of sweetness and the ideal oxygen-oxygen interorbital spacings for sweetness criteria in sugar molecules.
Acetates↗
Regurgitation in gorillas: possible model for human eating disorders (rumination/bulimia).
Regurgitation and reingestion behavior in gorillas is compared with two human disorders, rumination and bulimia. Eighty-four percent of captive gorillas that are more than 5 years old regurgitate and reingest. Comparisons are made on the basis of ontogeny, context, motor pattern, and intervention. There are more similarities between regurgitation and reingestion and rumination than between regurgitation and reingestion and bulimia. Regurgitation and reingestion resembles bulimia in parental/infant separation, lack of eating control, methods of induction, and some aspects of motor pattern. Regurgitation and reingestion resembles rumination in disrupted maternal/infant communication, context of the behavior (enjoy the taste of the regurgitant), several aspects of motor pattern, and treatment (increased food volume).
Animals↗
[Relations between structure and bitter taste of amino acids and peptides. I. Amino acids and related compounds].
About 60 amino acids, amino acid esters, N-acyl amino acids, amines, and other related compounds were tested for bitter taste. The recognition thresholds are in the range from 100 muMol/ml (L-2-amino butyric acid) to 0.8 muMol/ml (benzamide). Essential structural requirements for bitter compounds are a polar (electrophilic) group and a hydrophobic one, which must be arranged in a defined manner. The results are summarized in a model which shows the zones of contact between bitter compound and receptor.
Amino Acids↗
High salt intake. Sensory and behavioral factors.
Salt (NaCl) is a ubiquitous component of diets in developed countries. A major reason for this is that people judge many salted foods as more palatable than the same foods without salt. Because recent evidence indicates that an acceptable salt substitute is unlikely, an understanding of the behavioral and sensory factors involved in maintaining high salt preference is a prerequisite to successful programs aimed at reducing intake. Although little evidence exists for a genetic determination of individual differences in consumption and preferred level of salt, more research in this area is necessary. Considerable data support the view that the optimal level of salt in the diet is determined in part by the level an individual is currently consuming; increasing or decreasing customary salt intake, as long as the salt is tasted, increases or decreases the preferred level of salt in food. Although these data are consistent with a hypothesis that optimal salt preferences are learned, other data, from both animal models and human developmental studies, suggest that salt preference has an innate component. Furthermore, early experience with low or high salt diets may have a long-term impact on preferred salt levels. Liking for salt, similar to liking for sweets, has an innate basis that can be modified by individual experience.
Behavior↗
Modeling influences on alcoholics' rates of alcohol consumption.
Two experiments were designed to examine modeling influences on alcoholics' alcohol consumption. Three male alcoholics were paired with confederates, posing as alcoholics. In Experiment 1, alcoholic-confederate pairs participated in a 1-hour taste-rating task, which involved rating different wines on a list of adjectives. Experiment 2 consisted of 1-hour ad lib access to wine in a naturalistic bar setting. In both experiments, confederates alternated 15-minute periods of heavy and light consumption, drinking fluids resembling wine. The amount of wine consumed by alcoholics in each period was secretly recorded and the data examined on a single subject basis. In Experiment 1, two subjects increased and decreased consumption along with their confederate. The third subject followed the confederate's pattern only after the confederate demonstrated heavy consumption. All three subjects varied consumption with the confederate during Experiment 2, performed later on the same day. These results suggest that alcoholics' alcohol consumption can be modified by the social influences of modeling. The implications of this finding for the loss of control hypothesis and alcoholism treatment maintenance were discussed.
Adult↗
High-resolution solution structure of gurmarin, a sweet-taste-suppressing plant polypeptide.
Gurmarin is a 35-residue polypeptide from the Asclepiad vine Gymnema sylvestre. It has been utilised as a pharmacological tool in the study of sweet-taste transduction because of its ability to selectively inhibit the neural response to sweet tastants in rats. We have chemically synthesised and folded gurmarin and determined its three-dimensional solution structure to high resolution using two-dimensional NMR spectroscopy. Structure calculations utilised 612 interproton-distance, 19 dihedral-angle, and 18 hydrogen-bond restraints. The structure is well defined for residues 3-34, with backbone and heavy atom rms differences of 0.27 +/- 0.09 A and 0.73 +/- 0.09 A, respectively. Gurmarin adopts a compact structure containing an antiparallel beta-hairpin (residues 22-34), several well-defined beta-turns, and a cystine-knot motif commonly observed in toxic and inhibitory polypeptides. Despite striking structural homology with delta-atracotoxin, a spider neurotoxin known to slow the inactivation of voltage-gated Na+ channels, we show that gurmarin has no effect on a variety of voltage-sensitive channels.
Amino Acid Sequence↗
Conditioned taste aversion is a confound in behavioral studies that report a reduction in the reinforcing effects of drugs.
Pharmacologic agents with a potential to attenuate the reinforcing properties of drugs of abuse may have an important role in the treatment of drug addiction. The reduction of drug self-administration and sweet solution intake are two common animal models employed to screen for promising therapeutic agents. When these agents are effective in suppressing the behavior maintained by drugs of abuse, the cause is usually attributed to a neuronal mechanism such as the modification of neurotransmitters that subserve reinforcement. These experiments present data for an alternate interpretation which suggest that some of these agents produce a conditioned taste aversion (CTA) that acts as a confounding variable in the screening of potential therapeutic agents. Both carbamazepine and isradipine were shown to establish a CTA at doses reported to attenuate the reinforcing properties of drugs of abuse. It is concluded that CTA represents a potential experimental confound in studies of pharmacologic agents that appear to attenuate the reinforcing properties of drugs. These results suggest that screening for a CTA is necessary in any paradigm that measures the suppression of consummatory behavior in response to pharmacologic intervention.
Analgesics, Non-Narcotic↗
Chronic mild stress-induced anhedonia: greater effect in a genetic rat model of depression.
The effects of acute and chronic stressors on saccharin intake and preference in the hypercholinergic Flinders Sensitive Line (FSL) rat, a putative genetic animal model of depression, were studied and compared to the control Flinders Resistant Line (FRL) rats. Overall, the FRL rats drank significantly less saccharin and water than the FSL rats when compared over a wide range of saccharin concentrations (0.01-5%) under baseline conditions. A 0.02% saccharin concentration was used in subsequent experiments. We observed a significant suppression of saccharin intake/preference at 1 h following a single 5-min exposure to cold swim stress only in FSL rats. There was a tendency to increase saccharin intake in both lines at 1 h following a scrambled foot shock stress. These effects of acute stressors disappeared upon retesting for saccharin consumption/preference 23 h after the stress. Chronic 4-week exposure to unpredictable mild stressors significantly (p < 0.01) decreased saccharin consumption in the FSL rats, but not in the FRL rats. The FSL rats also exhibited a significantly greater decrease in saccharin preference (-24% vs. prestress baseline, as compared to -7% in FRL controls, p < 0.05). In conclusion, FSL rats appear more prone than the FRL rats to chronic, as well as immediate acute, stress-induced anhedonic effects. This outcome further supports the notion that the FSL rat is a useful model of a genetic predisposition to depressive-like reactions.
Animals↗
Sucrose and quinine intake by maternally-deprived and control rhesus monkeys.
Clinical depression is often characterized by a loss of interest or pleasure in formerly enjoyable activities. Analogs of anhedonia are established in rats, but the generality of this phenomenon to other species is unknown. Maternally-deprived rhesus macaques show a wide range of behavioral abnormalities that are reversed by chronic antidepressant treatment. We tested consumption by maternally deprived versus control macaques of sweetened (seven sucrose concentrations) or bitter water (four quinine concentrations) versus plain water to evaluate a non-human primate model of depression for signs of anhedonia. All monkeys consumed more sweetened than tap water, but maternally-deprived monkeys had a diminished preference for sweetened water than did controls. However, maternally deprived animals consumed more bitter water than did controls. Baseline fluid consumption did not differ. The data suggest that 'anhedonia' in animal models may be secondary to a generally attenuated responsiveness to stimuli, rather than a unitary reduction in responsiveness to the appetitive properties of stimuli. We conclude that maternally-deprived rhesus monkeys do not display gustatory signs of anhedonia, but rather of insensitivity to gustatory stimuli.
Animals↗
Palatable fluids do not affect alcohol intake and its reduction by serotonergic compounds in alcohol-preferring cAA rats.
1-(2,5-Dimethoxy-4-iodophenyl)-2-aminopropane (DOI) decreases alcohol intake by alcohol-preferring cAA rats more selectively than fluoxetine in a two-bottle alcohol vs. water paradigm. We report now that availability of sucrose or saccharin in a 3rd bottle does not affect (1) alcohol intake, supporting further the validity of this model of alcoholism, nor (2) the selectivity profile of the alcohol intake-reducing effects of these compounds. It is hypothesized that reduction of alcohol intake by DOI is not simply due to decreased intake of palatable fluids.
Alcohol Drinking↗
Morphine dependent behaviour in rats: some clinical implications.
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Animals↗
Effect of intracranial electrical stimulation on the primary learned aversion to LiCl and the generalized aversion to NaCl.
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Animals↗