The induction of c-Fos in the NTS after taste aversion learning is not correlated with measures of conditioned fear.

The induction of c-Fos-like immunoreactivity (c-FLI) in the nucleus of the solitary tract (NTS) has been shown to be correlated with behavioral expression of a conditioned taste aversion (CTA). However, because this cellular response is also dependent on an intact amygdala, it may represent the activation of a stress-related autonomic response. The present experiments addressed this possibility by evaluating the correlation between c-FLI in the intermediate division of the NTS (iNTS) and 2 measures of conditioned fear: freezing and changes in mean arterial pressure (MAP) and heart rate (HR). Exposure to the taste conditioned stimulus (CS) resulted in a marked induction of c-FLI in the iNTS, whereas exposure to a fear CS did not. Further, exposure to a taste CS did not selectively lead to increases in MAP or HR. Results suggest that induction of c-FLI in the iNTS may reflect the activation of a cell population whose function is unique to the CTA paradigm. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Taste aversion learning in fyn mutant mice.

Conditioned taste aversion (CTA) learning is a robust form of classical conditioning in which animals rapidly associate a flavor with aversive internal symptoms. The present study assessed CTA learning in transgenic mice deficient in a specific nonreceptor tyrosine kinase (the fyn mutant). Fyn mutants show impaired long-term potentiation and marked deficits in acquisition of spatial learning tasks. To assess whether they are also impaired in CTA learning. fyn mutant and wild-type mice received 2 conditioning trials consisting of access to a flavored solution followed by administration of LiCl. Fyn mutant mice acquired significant CTAs following a single conditioning trial and these aversions were comparable to those seen in wild-type mice. These results indicate that the fyn mutation does not interfere with the acquisition of CTAs and hence that this mutation is not associated with a global learning deficit. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Forebrain contribution to the induction of a brainstem correlate of conditioned taste aversion. II. Insular (gustatory) cortex

We report a new form of congenital muscular dystrophy (CMD) in 4 patients from three unrelated families with probable autosomal-recessive inheritance. All patients had the clinical characteristics of merosin-positive congenital muscular dystrophy, but had marked mental retardation. The disease was slowly progressive and 1 patient died from dilated cardiomyopathy at the age of 13 years. In addition to dystrophic changes with necrosis and regeneration in muscle, the most striking finding was mitochondrial depletion in the center of the sarcoplasm. Mitochondria at the periphery of fibers were markedly enlarged ("megaconial" appearance) with complicated cristae, and contained a normal amount of mitochondrial DNA by in situ hybridization. Mitochondrial enlargement may represent functional compensation for mitochondrial depletion in the central sarcoplasm, where myofibrillar degeneration occurred.     

Development of the enhanced neural response to NaCl in Fischer 344 rats

Duplications of the esophagus or stomach alone are infrequent, and complete foregut duplication has only rarely been described. Most combined esophagogastric duplications present within the first year of life, and if communication with the normal alimentary tract does occur, it does so only either above or below the diaphragm. This report illustrates a case of continuous duplication of the esophagus and stomach with communication to the normal alimentary tract at both proximal and distal ends. Operative management and a review of the literature and embryology are described.     

The CS–US interval and taste aversion learning: A brief look.

Temporal parameters of taste aversion learning are known to differ markedly from other learning paradigms in that acquisition occurs despite lengthy delays between exposure to conditioned (CS) and unconditioned stimulus (US). Far less consideration has been paid to very brief CS-US intervals and the possibility that this learning may also be distinguished by an ineffectiveness of close temporal contiguity between CS and US. The effectiveness of a very brief CS-US interval (10 s) was compared with that of 2 lengthier intervals (15 and 30 min). Temporal control of CS delivery (0.15% saccharin solution) into the oral cavity and US delivery (7.5 mg/kg apomorphine hydrochloride) into circulation involved infusion pumps and indwelling catheters. Using a 1-trial learning paradigm, CS-US delays of 15 and 30 min led to significant aversions whereas the 10-s CS-US interval did not, suggesting that close temporal contiguity between CS and US is neither necessary nor sufficient for conditioned taste aversion acquisition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dopamine and sodium appetite: Antagonists suppress sham drinking of NaC1 solutions in the rat.

Sodium (Na) ingestion in rats depleted of Na is a strong, motivated behavior that is enhanced further when depleted rats are sham drinking. Dopamine plays a critical role in motivation, including reward associated with consumption of palatable tastes. The present studies assessed the role of dopamine in real and sham drinking of NaCl solutions after Na depletion with the diuretic furosemide (10 mg/kg). Dopamine (D2) receptor antagonists were evaluated (Haloperidol [0.1 mg/kg] and raclopride [0.2 mg/kg]), for their effects on 2 sham and real drinking of 0.3 M NaCl. Sham drinking was markedly reduced by both antagonists whereas real drinking was unaffected. These effects did not appear to be due to malaise or suppression of motor behavior because drug-treated animals were able to increase ingestion substantially when offered less concentrated NaCl (0.1 M). These results suggest that the positive motivating properties of NaCl stimulation in depleted, sham-drinking rats are mediated by central D2 receptors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)