Distribution of fos-like immunoreactivity in the medullary reticular formation of the rat after gustatory elicited ingestion and rejection behaviors

The distribution of neurons in the medullary reticular formation (RF) activated by the ingestion of sucrose or rejection of quinine was examined using standard immunohistochemical techniques to detect the expression of the Fos protein product of the immediate-early gene c-fos. Double-labeling techniques were used to gain further insight into the possible functional significance of RF neurons exhibiting Fos-like immunoreactivity (FLI). Compared with sucrose and unstimulated controls, quinine elicited significantly more FLI neurons in three specific RF subdivisions: parvocellular reticular nucleus (PCRt), intermediate reticular nucleus (IRt), and dorsal medullary reticular nucleus (MdD). Moreover, the number of FLI neurons in the RF of quinine-stimulated animals was significantly correlated with the degree of oromotor activity. Thus, the distinct distribution of FLI neurons throughout the RF after quinine may reflect the activation of a specific oral rejection circuit. The double-labeling results indicated a high degree of segregation between FLI neurons and premotor projection neurons to the hypoglossal nucleus (mXII) retrogradely labeled with Fluorogold. Thus, although there were a significant number of double-labeled neurons in the RF, the major concentration of premotor projection neurons to mXII in IRt were medial to the preponderance of FLI neurons in the PCRt. In contrast, there was substantial overlap between FLI neurons in the RF and labeled fibers after injections of the anterograde tracer, biotinylated dextran into the rostral (gustatory) portion of the nucleus of the solitary tract. These results support a medial (premotor)/lateral (sensory) functional topography of the medullary RF.     

Role of ingestion in odor-toxicosis learning in the rat.

Conducted 2 experiments with 32 and 34 male Charles River albino rats, in which Ss evidenced aversions to an odor paired with toxicosis in both drinking and exploratory behavior tests. Ingestion during odor-toxicosis conditioning in Exp I resulted in stronger aversions only in tests involving drinking the same solution as had been ingested during training, despite the absence of enhanced aversions to the flavor of the solution used. This result is interpreted as evidence that Ss drinking during conditioning acquired aversions not only to the CS odor but also to additional cues arising from an interaction of the CS odor and the flavor of the ingested solution. Exp II showed that these interaction cues were not the result of a flavor imparted to the ingested substance by dissolved molecules of the odorizing agent. (15 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditioned suppression to odorous stimuli in the rat.

Used a modified conditioned-suppression technique to train 6 male Sprague-Dawley rats to criterion discrimination of amyl acetate at 10-2.0 of vapor saturation. The magnitude of suppression was also recorded as a function of concentration and amyl acetate, with the concentrations presented by the method of constant stimuli. Amyl acetate thresholds were 10-5.50, 10-5.25, 10-5.70, 10-5.75, 10-5.90, and 10-5.80 of vapor saturation for the Ss. Mean thresholds for butyl, amyl, hexyl, and heptyl acetates were also determined. An independent measurement of the amyl acetate concentrations determined by the olfactometer was made with gas-liquid chromatography. Results indicate that the methodology employed is accurate for a 6 log unit range. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ability of newborn infants to discriminate sapid substances.

Observed taste preferences in newborn infants to determine (a) the ability of newborns to discriminate different sapid substances and different molar concentrations within those substances and (b) the role of immediate prior sucking and ingestion experience in altering subsequent oral behavior. Ss were 48 male and 48 female full-term, single birth 1-3 day old infants. Results show that the sucking rate varied with the substance (glucose, sucrose, and water) delivered through the nipple and with the order in which the substances were presented within a test session. Amount of fluid delivery was controlled automatically by the infant's own sucking behavior, a procedure which provides a taste preference report as well as evidence of the discriminability of taste substances. It remains to be demonstrated that profound taste aversions, resulting in complete inhibition of sucking, are also present at this young age. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

{l}-DOPA-induced air-stepping in the preweanling rat: Electromyographic and kinematic analyses.

Ontogenetic changes in intralimb coordination may result from maturation of the central pattern for locomotion. maturation of peripheral efferents, changes in afferent modulation of the centrally generated pattern, interactions with the substrate, biomechanical changes within the limb itself, or a combination of these. Electromyograms obtained from three hindlimb extensors of rats on Postnatal Days (PND) 5, 10, 15, or 20, during episodes of coordinated {l}-DOPA-induced air-stepping, showed that muscle activation preceded extension of the corresponding joints at all ages. The delay between the onset of extensor activity and the onset of joint extension increased during ontogeny and was greatest at PND 20. Ontogenetic changes in the relative timing of muscle activity and corresponding joint movements probably resulted from changes in biomechanical factors, changes in afferent modulation of central motor output, or both. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Control of ingestion by oral habituation in rat pups.

The role of habituation of mouthing activity in the control of ingestion was investigated in 6-, 12-, and 18-day-old rat pups. In pups at all ages, oral habituation to a flavored diet inhibited ingestion of a continuous oral infusion of that same diet. 12-day-old pups that had orally habituated to a diet continued to consume less of a continuous oral infusion of that diet both 30 min and 3 hrs later, and the duration of suppressed ingestion was shown to be dependent on the rate of stimulus presentation during habituation experience. These data suggest that oral habituation may be a diet-specific influence on both intra- and intermeal patterning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Paradoxical autonomic responses to aversive stimuli in the developing rat.

The goals of this research were to determine (1) the change in heart rate elicited by aversive auditory stimuli in the laboratory rat at different ages and (2) the autonomic origins of those changes at each age. The results of the 1st 2 experiments showed that aversive white noise stimuli elicited cardiac deceleration in preweanling (16-day-old) rats and cardiac acceleration in weanling (23-day-old), periadolescent (30-day-old), and adult (60-day-old) rats. Subsequent experiments showed that (1) the decrease in heart rate elicited by the noise stimulus in preweanling rats was mediated by parasympathetic activation of the heart, (2) the stimulus-elicited increase in heart rate elicited by the noise in periadolescent rats was mediated by parasympathetic withdrawal of the heart, and (3) the noise-induced increase in heart rate in adult rats was primarily mediated by sympathetic activation of the heart. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The relative effectiveness of salt stimuli for the rat.

Determined the relative detectability of 8 salts over a molar concentration range of .0125-.80 in an experiment with 5 male hooded rats. The detectability of those salts, which have a strong sour or bitter quality, is substantially greater when compared with sodium chloride, than their relative effectiveness as determined by the size of the evoked response in the chorda tympani. It is suggested that, like quinine, these salts are more effective on the posterior tongue. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Autonomic origins of cardiac responses to nonsignal stimuli in the rat.

Heart rate (HR) and blood pressure responses to nonsignal auditory stimuli were measured in rats after saline or pharmacological blockade of the sympathetic or vagal innervation of the heart. HR responses to the low-intensity stimulus were predominantly deceleratory, whereas responses to the high-intensity stimulus were more notably acceleratory. Both stimuli elicited a biphasic pressor–depressor response, although potential baroreflex influences accounted for only a small proportion of the HR response variance. Deceleratory responses to the low-intensity stimulus were eliminated by scopolamine and thus appeared to be predominantly of vagal origin. Acceleratory response to the high-intensity stimulus appeared to be mediated primarily by sympathetic activation because it was substantially attenuated by the β? antagonist atenolol. Furthermore, HR responses to the low-intensity stimulus appeared to reflect coactivation of both sympathetic and vagal systems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reflex-inhibiting stimuli and the refractory period of the acoustic startle reflex in the rat.

Previous studies show that if acoustic startle stimuli are presented in pairs, then the reaction to the 2nd stimulus (S2) is reduced, with the size of the refractory decrement determined by the interstimulus interval and the relative intensity of the 1st stimulus (S1). If a neutral stimulus (p) is presented just prior to S1, then the reaction to S1 is similarly inhibited, revealing the phenomenon of prestimulus inhibition. In 2 experiments with male albino Holtzman rats (N = 24) it was found that suppression of the reflex to S2 by S1 was unaffected by prestimulus inhibition of S1 (i.e., reflex amplitudes associated with S2 were identical in pS1-S2 series and S1-S2 series). In contrast, a reduction in the intensity of S1 relative to S2 did reduce the effect of S1 on S2. These data indicate that prestimulus inhibition of the reflex to S1 does not result because the preliminary stimulus attenuates the sensory impact of S1. The inhibitory process may be presumed to have a central locus. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modulation of the inspiratory-related activity of hypoglossal premotor neurons during ingestion and rejection in the decerebrate cat

BACKGROUND: The aim of this work was to study the immunoreactive forms of bone Gla protein (BGP) present in conditioned media of human osteoblast cultures (BGP released from osteoblast) and in the sera of healthy adult control subjects and patients with bone pathologies (chronic renal failure on haemodialysis, Paget's disease of bone and post-menopausal osteoporosis). METHODS: The technical procedure used was a combination of high-performance liquid chromatography (HPLC) and different BGP assays with several specificities to analyse BGP levels in the different HPLC fractions. Aliquots of conditioned media or sera were purified through a Sephadex G-50m column and by HPLC (C4 reverse-phase column) in a 25-40% acetonitrile gradient. Two-minute fractions were collected and divided into three aliquots in order to determine osteocalcin content using three different assays: (a) ELSA-OST-NAT IRMA, which only detects intact osteocalcin; (b) ELSA-OSTEO IRMA, which detects intact osteocalcin and N-terminal fragments; and (c) OSCA Test RIA, which detects intact osteocalcin, C-terminal and other fragments. RESULTS: We found different immunoreactive forms of osteocalcin in the culture medium of human osteoblasts and in sera from control subjects and patients for the bone pathologies studied. We did not find great qualitative differences between the immunoreactive osteocalcin profile found in the culture medium from human osteoblasts and the sera from healthy control subjects. However, the different bone pathologies show different characteristic patterns of immunoreactive forms of osteocalcin. CONCLUSIONS: An interesting finding has been the detection, both in sera and in osteoblast culture media, of several immunoreactive forms of intact osteocalcin that eluted from HPLC at different acetonitrile percentages, and therefore correspond to different molecular forms.     

Adrenalectomy reduces peripheral neural responses to gustatory stimuli in the rat.

The adrenalectomized rat, because of excessive body sodium loss, has been an important animal model for studying the physiological mechanisms underlying salt ingestion. To investigate the mediation by peripheral taste responsivity of changes in salt intake, multiunit responses of the chorda tympani nerve to various concentrations of NaCl, KCl, and LiCl, hydrochloric acid, and quinine hydrochloride were recorded from 18 adrenalectomized or intact male Sprague-Dawley rats. To control for a generalized decrease in sensory sensitivity, recordings from this auriculotemporal nerve to tactile stimulation of the pinna were also performed. There were no group differences in amplitude of the integrated neural responses to tactile stimulation. The largest decrease in gustatory responsivity occurred for suprathreshold concentrations of NaCl and LiCl. Data are discussed with reference to possible mechanisms underlying this neural alteration and the role that reductions in salt taste responsivity play in mediating increases in salt intake. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Electromyographic analysis of grand-plié in ballet and modern dancers

PURPOSE: The purpose of this report is to describe lower extremity muscle activity in grand-plié, as determined by EMG analysis; to compare and contrast muscle function in grand-plié and demi-plié to support the hypothesis that grand-plié is not simply a deeper demi-plié, but rather a fundamentally different movement in terms of muscle use; and to present further evidence in support of the hypothesis that ballet dancers use muscles differently than modern dancers in dance movement. METHODS: Surface electromyography was used to analyze lower extremity muscle activity during grand-plié in first position with lower extremities turned out in five ballet and seven modern female professional dancers. RESULTS: Electromyographic (EMG) activity of tibialis anterior included continuous activity from heel-off during the lowering phase, through midcycle, and ending at heel-on during the rising phase in all grand-pliés; the majority of tibialis anterior EMG tracings in ballet dancers had additional activity at the end of the rising phase. All EMG tracings for vastus lateralis and medialis included a peak of activity during the lowering phase, a decrease (valley) at midcycle, followed by another peak during the rising phase; increased activity at the end of the rising phase was observed in most grand-plié in ballet, and not modern, dancers. Adductor EMG activity was also observed in all tracings with a peak during the lowering phase from heel-off to midcycle, a valley at midcycle, followed by a peak of activity in early rising phase; the midcycle valley was of lower, and the rising phase peak of higher, activity in ballet compared with modern dancers. Variation of EMG patterns was observed for lateral and medial gastrocnemius, gluteus maximus, and hamstrings. CONCLUSIONS: The data support the concept that lower extremity muscle activity in dance movement is comprised of three major types: (a) unique, characteristic activity required for the execution of the movement; (b) varied activity which is characteristic of dancers of different dance idioms; and (c) varied activity which may depend on factors such as balance, personal habit, and individual training background. Furthermore, EMG activity of vastus lateralis and medialis at the midcycle valley in grand-plié was significantly less in ballet dancers than in modern dancers despite similar degree of knee flexion, suggesting that ballet dancers may have lower patellofemoral joint reaction force at midcycle than modern dancers.     

Electromyographic patterns associated with nonnutritive sucking in 11–13-day-old rat pups.

Three experiments used an EMG technique to measure the frequency, duration, and intensity of nonnutritive sucking (NNS) in 56 11–13 day old Wistar pups. Ss were separated from their mothers for 2–6 or 20–24 hrs and then allowed to suckle an anesthetized dam for up to 3 hrs without receiving any milk. Jaw-muscle EMG and nipple detachments were recorded. EMG patterns representing 2 discrete modes of sucking were reliably discerned, as were changes in overall intensity of EMG. 20–24 hr separated Ss engaged in more frequent NNS bouts and bouts of longer duration than 2–6 hr separated Ss. Ss separated by 20–24 hrs also engaged in a mode of NNS not seen in 2–6 hr separated Ss. Overall EMG intensity was higher and frequency of nipple detachments was lower in Ss separated for 20–24 hrs. In both groups, but particularly the 20–24 hr Ss, frequency of some NNS patterns decreased as the length of the "dry" suckling increased. EMG intensity also decreased over time in both groups, and frequency of nipple detachments increased in 2–6 hr separated Ss. Data indicate that some aspects of NNS are highly labile and respond to variations of both deprivation from the mother and nutritive deprivation. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Chemical stimulation of the brain: Relationship between neural activity and water ingestion in the rat.

Implanted cannulae in the lateral septal nucleus, lateral hypothalamic area, or lateral caudate nucleus of 76 male Long-Evans rats. Ss then received injections of carbachol, atropine sulfate, or isotonic saline. Injecting carbachol into cholinergic drinking sites in the limbic system (septal nucleus or lateral hypothalamus) produced an immediate increase in neural firing at the stimulated site and at a contralateral nonstimulated site. The time course of the change in neural firing was similar to the time course of water ingestion. Increased neural firing was not produced by cholinergic stimulation of nondrinking caudate nucleus sites or by atropine or isotonic saline injection into the limbic system or caudate nucleus. Results suggest that drinking results from increased neural firing in a diffuse cholinergically coded circuit whose activity facilitates water ingestion. (27 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Electromyographic biofeedback and neuromuscular rehabilitation.

Electromyographic biofeedback has now been used with apparent success, although most often in an uncontrolled fashion, in the rehabilitation treatment of a wide range of neuromuscular disorders. These have included peripheral nerve-muscle damage, spasmodic torticollis, the stroke hemiplegias, and cerebral palsy. Studies of these applications are reviewed, and some specific problems that should be the topic of further controlled research are outlined. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development and habituation of the heart rate orienting response to auditory and visual stimuli in the rat.

Studied development and habituation of responsivity to sound and visual stimuli in 120 8–19 day old Sprague-Dawley pups by using a change in heart rate (HR) as the indicant response (Exp I). A change in HR to sound (white noise) first occurred around 14–25 days of age and was acceleratory in nature. Within 3 days, the direction of the HR response shifted to bradycardia. The HR response to light was also characterized by tachycardia in young pups (14 days), which shifted to bradycardia as the pups matured (16 days and older). In Exp II, the HR response of 15- and 19-day-old Ss was studied at 3 auditory stimulus intensities (60, 70, and 90 db, B scale). Stimulus intensity influenced the magnitude of the cardiac response in the 19-day-old pups. Data suggest that even weak sensory stimuli elicited a defensive reaction (HR acceleration) during the 1st few days that followed onset of function in each sensory system; later in development, the same stimulus elicited an orienting response (cardiac deceleration). (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of interference stimuli on the acquisition of learned aversions to foods in the rat.

Developed a learned food aversion paradigm to investigate characteristics of aversion learning likely to be involved in nutrient selection. The development of aversions to a relatively familiar, complete food was examined in 6 experiments with 186 Wistar-Furth rats with continuous access to that food. Learned food aversions were observed that were specific to the particular diet present during a sequence of toxic drug injections. Novel liquids and solids were also introduced in association with drug treatment to examine their effectiveness as interference stimuli. Flavored solutions, which have previously been reported to interfere with conditioned taste aversions, had little or no effect on learned aversions to the diet. This lack of interference by novel flavored liquids was coupled with significant conditioned aversions to the novel liquids themselves. Novel flavored solutions were contrasted with novel foods, which were extremely effective as interference stimuli in this paradigm. Possible bases for the observed differences in interference effects of foods and drinks are examined. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)