Taste reactivity as a dependent measure of the rapid formation of conditioned taste aversion: A tool for the neural analysis of taste-visceral associations.

Investigated the ability of animals to form taste aversions following neural manipulations. In Exp 1, 10 rats received intraoral infusions of sucrose every 5 min starting immediately after the injection of LiCl. 12 controls were injected with NaCl. Oromotor and somatic taste reactivity behaviors were videotaped and analyzed. Lithium-injected Ss decreased their ingestive taste reactivity over time; aversive behavior increased. Controls maintained high levels of ingestive responding and demonstrated virtually no aversive behavior following sodium injection. Ss were tested several days later for a conditioned taste aversion (CTA). Rats previously injected with lithium demonstrated significantly more aversive behavior than controls. Exp 3 revealed that when similarly treated rats were tested for a CTA while in a lithium-induced state, difference in the ingestive behavior was observed. In Exp 2, naive rats were injected with NaCl or LiCl but did not receive their 1st sucrose infusion for 20 min. Ss also received infusions at 25 and 30 min postinjection. There were no differences in the task reactivity behavior displayed. Rats dramatically changed their oromotor responses to sucrose during the period following LiCl administration, provided the infusions started immediately after injection, a change attributable to associative processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

2-Mercaptoethanol is a survival factor for olfactory, cortical and hippocampal neurons in short-term dissociated cell culture

A medium originally designed for lymphocyte growth promoted robust survival of olfactory receptor neurons (ORNs) in short-term (4-day), dissociated cell culture. The key ingredient for survival of neurons in both serum and serum-free conditions was 2-mercaptoethanol (2-ME). Enhancement of survival may be thiol-mediated because two other thiol compounds, 2-mercaptoethylamine and monothioglycerol, also increased ORN survival. Addition of 2-ME also significantly increased survival of embryonic cortical and hippocampal neurons in a serum-free medium, and embryonic cortical neurons in a serum-containing medium. After plating and growth in a serum-free medium containing 2-ME, survival of all three types of neurons was equivalent to, or greater than, survival in serum-containing media. Thus, thiols such as 2-ME promote the survival of multiple types of neurons in short-term cell culture.     

Contribution of the rat's neocortex to ingestive control: I. Latent learning for the taste of sodium chloride.

Conducted 3 experiments with 13 decorticate and 12 control male Sprague-Dawley rats to investigate whether some permanent ingestive control deficit would be revealed in a latent learning paradigm for salt taste. The ability of Ss to associate how they obtained the taste of NaCl when Na-replete was assessed by examining barpresses during extinction when Na-depleted. Intact Ss exposed to 4–6 hrs of NaCl taste training retained the association after decortication; decorticate Ss exposed to the same training acquired the association. Decorticate Ss exposed to as little as 2 min of NaCl taste training demonstrated the ability to associate barpressing with NaCl by their resistance to extinction. This association was specific to NaCl training. It is concluded that subcortical structures are adequate for latent learning involving NaCl taste. Conversely, previous research has shown that the neocortex is required for the retention of taste-aversion learning for the same taste. (43 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tetrabromophthalic anhydride in self-extinguishing polyesters

Polyesters based on tetrabromophthalic anhydride are self-extinguishing in the range of 8–12% bromine content and nonburning at higher levels of the latter. An increase in bromine content results in higher flexural and tensile strenght and flexural modulus, while impact resistance is slightly reduced. Mechanical Properties vary with bromine content in the 0–12% range and remain practically unaffected at higher levels up to 23%.     

Sodium depletion enhances salt palatability in rats.

Stereotyped fixed action patterns (FAPs) elicited in rats by oral infusions of taste solutions can be classified as either ingestive or aversive. They reflect the palatability of the taste and can be modified by learning and by the physiological state of the animal. The present 2 experiments, with 5 male Sprague-Dawley rats, demonstrated that when the physiological state of the S was altered by sodium depletion, the pattern of FAPs elicited by oral infusions of 0.5 M NaCl shifted from a mixture of ingestive and aversive components (while sodium replete) to exclusively ingestive ones (while sodium deplete). This shift in taste reactivity occurred the 1st time the Ss were made sodium deplete. A similar shift did not accompany infusions of 0.01 M HCl, a taste solution that also elicited mixed ingestive and aversive FAPs. This result suggests that the shift in response to NaCl was not due to a general change in ingestive bias or to a general taste deficit. On the basis of the change in FAPs, it is concluded that the palatability of highly concentrated salt solutions increases in sodium-deplete rats. Such a shift in salt palatability may be instrumental in directing the appetitive behavior of the animal. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the substitution of conventional corrosion tests by an electrochemical potentiokinetic reactivation test

Nickel-based alloy 625 was investigated by means of a conventional corrosion test (Streicher-test according to ASTM G28A [1]) and an electrochemical potentiokinetic reactivation test (according to ASTM G108 [1], with some modifications). Susceptibility to intergranular corrosion after various heat treatments was examined by using both test methods and the results were compared. Dependent on the type of heat treatment applied, both methods showed partially different results. Possibilities and limitations of replacing Streicher-test with EPR-test are pointed out and commentated. In conclusion, the EPR-test presents itself as a promising and quick investigation technique for detecting susceptibility to intergranular corrosion in nickel-based alloys.     

Selective control of muscle activation with a multipolar nerve cuffelectrode

Acute experiments were performed on adult cats to study selective activation of medial gastrocnemius, soleus, tibialis anterior, and extensor digitorium longus with a cuff electrode. A spiral nerve cuff containing twelve dot electrodes was implanted around the sciatic nerve, and evoked muscle twitch forces were recorded in six experiments. Spatially isolated dot electrodes in four geometries (monopolar, longitudinal tripolar, tripolar with four common anodes, and two parallel tripoles) were combined with transverse field steering current(s) from an anode(s) located 180° around from the cathode(s) to activate different regions of the nerve trunk. A selectivity index was used to construct recruitment curves for a muscle with the optimal degree of selectivity. Physiological responses were correlated with the anatomical structure of the sciatic nerve by identifying the nerve fascicles innervating the four muscles, and by determining the relative positions of the electrodes and the nerve fascicles. The results indicated that the use of transverse field steering current improved selectivity. The relative performance of the various electrode arrangements is discussed     

Effect of current pulses on the temperature distribution and microstructure in TIG tantalum welds

The welding process employed for bonding metals by melting and solidification produces a joint which is generally inhomogeneous. The micro structure of the fused zone and its adjacent heat affected zone, HAZ, is usually different from the microstructure of the parent metal, obtained by mechanical working or heat treatment. The fused zone is usually composed of coarse columnar grains characteristic of as-cast structures. If the parent metal was originally cold-worked, recrystallization will occur in the HAZ, producing a coarse grained structure. As a result of the effect of the microstructure on the mechanical properties of the weld, the obtained joint may be weaker than the rest of the structure which was not affected by the heat of the welding. Although in some cases it is possible to improve the properties of the weld by post-welding heat treatment, different methods are tried in order to improve the microstructure directly during the welding process.     

Relation of consummatory responses and preabsorptive insulin release to palatability and learned taste aversions.

In 6 experiments with 68 male Sprague-Dawley rats, the oral stimulation arising from food in the mouth produced a stereotyped sequence of ingestive consummatory responses and a rapid release of insulin prior to the absorption of nutrients into the blood. Conversely, when noxious taste stimuli were infused into the mouth, a different, aversive set of consummatory responses was evoked, and no insulin was released. These experiments demonstrate that pairing a sapid taste solution with LiCl reversed the consummatory response sequence to subsequent presentations of that taste from ingestion to aversion and abolished the preabsorptive release of insulin to that taste; this indicated an experience-produced shift in the palatability of the taste. It was further shown that a palatable but categorically noncaloric taste elicited behavioral ingestion but no insulin release. It is concluded that separate but related control systems operate to produce consummatory behavior and ingestive neuroendocrine responses. (64 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)