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PubMed1995

[Decrease and asymmetry in taste perception in patients with nerve trunk damage].

The purpose of this article was the gustatory perception state study (NaCl solution perception) in patients with one-sided damages of branchial plexus as well as of radial, facial and ulnar nervous trunks. The decrease of gustatory perception was observed in 78 (70.3%) cases, while the lack of such alterations in 33 (29.7%) patients. The gustatory perception disturbances (increase of the absolute threshold on the ipsilateral tongue's half) took place in 82.2% and 69.6% at right and left limbs damages respectively. The results presented testified the strengthening of normally existing asymmetry in gustatory perception especially in patients with left-sided denervation. The degree of gustatory perception restoration may serve as a prognostic test at surgery of such patients.

Chronic Disease↗
PubMed1975

Colour-blindness and sensitivity to PTC in Hadza.

211 Hadza (Tanzania) males, including members of both western and eastern groups, were tested for red-green colour blindness with the Ishihara non-numeral plates. Three closely related individuals were considered to be protanopes. It is possible that they received the gene from an Isanzu ancestor. 118 individuals (both sexes) were tested for taste-deficiency to PTC using a single solution and a sorting test. 22% of the males and 27% of the females were considered to be non-tasters. Since this appeared to be a high figure for an African population a sample of 53 eastern Hadza males was later tested using solutions 1, 3, 5, 7, 9, 11, 13. A conservative interpretation of the threshold distribution gave an estimate of 43% non-tasters. Corrections were applied for the inclusion of close relatives in the samples. The results are discussed in relation to other African data.

Adolescent↗
PubMed2004

Testosterone and chemosensory detection in male Syrian hamster.

Gonadal steroids stimulate both sexual motivation and performance. However, steroid facilitation of appetitive sexual behavior is poorly understood. The present study determined if castration impairs chemosensory detection in male hamsters. Chemosensory cues are the principal sensory modality to initiate mating in this species. We compared LiCl-induced conditioned taste avoidance to female hamster vaginal secretion (FHVS) in gonad-intact and castrated males. Following overnight water deprivation, males received FHVS for 15 min, followed by LiCl (2 ml of 0.15 M) or saline ip. The next day, fluid consumption in a two-bottle choice test was recorded for 5.5 h. Pairings were repeated 4x. Initially, discrimination of FHVS from estrous females (10 or 100 microg/ml) was compared with plain water. Subsequently, we determined if males could distinguish FHVS from Syrian vs. Djungarian females or from estrous vs. anestrous females. When 100 microg/ml FHVS was paired with saline, all gonad-intact and 86% of castrated males preferred FHVS over water. However, when 100 microg/ml FHVS was paired with LiCl, the preference was reversed: 12.5% of intact males and 25% of castrates preferred FHVS (P < 0.05 vs. saline pairing). When exposed to 10 microg/ml FHVS, neither gonad-intact nor castrated males expressed conditioned taste avoidance, suggesting that 10 microg/ml FHVS is below the threshold for detection. Comparing discrimination of FHVS from Syrian and Djungarian females, only castrated males developed a significant conditioned taste avoidance to Syrian FHVS paired with LiCl. While 71% of castrated males preferred Syrian FHVS after saline pairing, only 12.5% of castrates preferred Syrian FHVS after pairing with LiCl (P < 0.05). In gonad-intact males, 57% preferred Syrian FHVS after saline pairing, while 14% preferred Syrian FHVS following LiCl pairing (P > 0.05). Neither gonad-intact nor castrated males successfully discriminated between FHVS from estrous and anestrous females. These data demonstrate that castrated males perform as well as gonad-intact males in a test of LiCl-induced conditioned taste avoidance. Therefore, it is unlikely that steroids enhance detection of sexually relevant chemosensory cues.

Animals↗
PubMed1994

A new gustometer for testing taste discrimination in the monkey.

A fully automated, 10-channel gustometer for use with nonhuman primates is described. The system, constructed primarily from commercially available components, includes an intelligence panel (containing sample spout, reward spout, and two operant response keys) that attaches to the door of a standard primate cage. The novel feature of the gustometer is a sample delivery spout that can be flushed, rinsed, and refilled within a specially designed rinsing chamber. All wetted surfaces of the gustometer are either Teflon, glass, or stainless steel. Flame photometric analysis confirmed the absence of cross-contamination between trials. Behavioral data collected from one rhesus monkey using a shock-suppression procedure demonstrates the detection threshold for sodium chloride. Improvements to the design, including the addition of pressurized sample delivery triggered by a lickometer circuit, are discussed.

Animals↗
PubMed1991

Central gustatory lesions: I. Preference and taste reactivity tests.

Bilateral electrophysiologically guided lesions were placed in the nucleus of the solitary tract (NST), the parabrachial nucleus (PBN), and the ventral posteromedial thalamic nucleus (VPMpc) of rats, and 15-min intake and taste reactivity (TR) responses elicited by 3 concentrations each of sucrose, NaCl, HCl, and quinine (Q) HCl were subsequently measured. Compared with controls, NST lesions had no significant effects on intake, and rats with PBN lesions consumed significantly more QHCl, sucrose, NaCl, and HCl. Thalamic lesions decreased sucrose intake. Analysis of TR responses showed that the QHCl threshold for aversive responses increased after VPMpc, PBN, and NST lesions. Rats with NST or PBN lesions were unresponsive to increasing sucrose concentration. TR responses elicited by NaCl and HCl were similar across the groups.

Afferent Pathways↗
PubMed2000

Effects of acids on neural activity elicited by other taste stimuli in the rat Chorda tympani.

The purpose of this study is whether the gustatory neural response of taste cell to a binary mixture with threshold concentration of acid becomes synergistic or antagonistic can be estimated from the whole chorda tympani (CT) nerve in the rat. The present data demonstrate that acids are synergistic enhancer for sugars, and suppressor for NaCl and QHCl, but no effect to glycine and alanine. These results suggest that the acid was modifying the interaction of the other stimulus with its transduction mechanism.

Acids↗
PubMed2001

Sweetener preference of C57BL/6ByJ and 129P3/J mice.

Previous studies have shown large differences in taste responses to several sweeteners between mice of the C57BL/6ByJ (B6) and 129P3/J (129) inbred strains. The goal of this study was to compare behavioral responses of B6 and 129 mice to a wider variety of sweeteners. Seventeen sweeteners were tested using two-bottle preference tests with water. Three main patterns of strain differences were evident. First, sucrose, maltose, saccharin, acesulfame-K, sucralose and SC-45647 were preferred by both strains, but the B6 mice had lower preference thresholds and higher solution intakes. Second, the amino acids D-phenylalanine, D-tryptophan, L-proline and glycine were highly preferred by B6 mice, but not by 129 mice. Third, glycyrrhizic acid, neohesperidin dihydrochalcone, thaumatin and cyclamate did not evoke strong preferences in either strain. Aspartame was neutral to all 129 and some B6 mice, but other B6 mice strongly preferred it. Thus, compared with the 129 mice the B6 mice had higher preferences for sugars, sweet tasting amino acids and several but not all non-caloric sweeteners. Glycyrrhizic acid, neohesperidin, thaumatin and cyclamate are not palatable to B6 or 129 mice.

Animals↗
PubMed2003

Rate of recovery of taste function after preservation of chorda tympani nerve in middle ear surgery with special reference to type of disease.

To study the recovery of function of the chorda tympani nerve, we examined by electrogustometry 79 patients (83 ears) with both preoperative normal function of the nerve and operative preservation of the nerve, every 2 days during hospitalization and at 6 months after surgery. For symptoms such as tongue numbness and taste disturbance, patients with noninflammmatory (NI) diseases (13/20 or 65.0%) showed a significantly higher rate of symptoms than did patients with chronic otitis media (COM; 13/35 or 37.1%) at 2 weeks after surgery (p = .032). The patients with NI diseases (5/20 or 25.0%) tended to show a higher rate of symptoms than did the COM patients (2/35 or 5.7%) or cholesteatoma patients (2/28 or 7.1%) at 6 months after surgery. The rate of recovery of the EGM threshold to normal at 2 weeks after surgery was significantly lower in NI disease patients (6/20 or 30.0%) than in COM patients (23/ 35 or 62.9%) or cholesteatoma patients (19/28 or 67.9%; p = .015 and .008, respectively). Thus, the patients with NI diseases had postoperative symptoms and elevation of EGM threshold more frequently than did the patients with inflammatory diseases.

Adolescent↗
PubMed2006

20-hydroxyecdysone deters oviposition and larval feeding in the European grapevine moth, Lobesia botrana.

European grapevine moth females (Lobesia botrana, Lepidoptera Tortricidae) select an oviposition site by tasting the host plant surface and then gluing a single egg on berries from grapes or from several other host plant species. In doing so, females should avoid ovipositing on plants that are detrimental to their progeny. Do they sense the same deterrent compounds as larvae, despite the fact that they do not have access to the same compartments of the plants? We tested this hypothesis with 20-hydroxyecdysone (20E), purified from Leuzea carthamoides. Phytoecdysteroids are usually found inside plant tissues and accessible to larvae in an aqueous phase, while adults would access them only through the epicuticular wax. We first confirmed that larvae avoid feeding on 20E and that they taste 20E with their lateral sensilla styloconica, at a threshold of 10(-6) M. Then, we tested whether adult females avoid ovipositing on glass spheres sprayed with 20E. When given a choice, females avoided laying eggs on a treated surface, at a threshold of 8 ng/cm(2). In addition, they deposited significantly fewer eggs in the presence of 20E. Presuming that legs play an important role in assessing the oviposition substrate, we assessed the sensitivity of their taste receptors. In females, 14 taste sensilla are located on the ventral side of the last tarsus of the prothoracic leg. One group of these sensilla house one neuron that is sensitive to 20E, with a detection threshold of about 10(-7) M. The same molecule is thus sensed both in larvae and adults of L. botrana where it respectively inhibits feeding and oviposition.

Animals↗
PubMed2005

Taste function after section of chorda tympani nerve in middle ear surgery.

OBJECTIVE: To investigate prospectively the clinical manifestations and the functional recovery of taste after section of chorda tympani nerve (CTN) during middle ear surgery, the subjective and objective study on the patients was performed. METHODS: Thirty-five patients underwent surgery with unilateral (n=32) or bilateral (n=3) section of CTN between January 2000 and April 2002. The patients were asked about taste symptoms before surgery and 2 weeks and 2 years after surgery. The CTN function was also measured with electrogustometry (EGM) at the same time points. RESULTS: In unilateral section of CTN, 19/32 (59.4%) complained of taste disorder and 11/32 (34.4%) tongue numbness. Most of these taste symptoms disappeared within 2 years although the EGM threshold did not recover. 16/17 patients (94.1%) who used to cook everyday had little difficulty in flavoring dishes. In bilateral section of CTN, the patients had no problem of taste at 2 years after surgery, either. CONCLUSION: These findings help explain the potential complications to the patients before surgery, although the number of cases was small in this series.

Adolescent↗
PubMed1990

Conditioned taste aversion is disrupted by prolonged retrograde effects of intracerebral injection of tetrodotoxin in rats.

Acquisition of conditioned taste aversion (CTA) is disrupted when 10 ng tetrodotoxin (TTX) is injected into both parabrachial nuclei of rats immediately after saccharin drinking and before LiCl poisoning (Ivanova & Bures, in press). Further analysis of this finding showed that parabrachial TTX injection (a) elicited retrograde amnesia also when applied 1, 2, or 4 days but not 8 days after CTA acquisition; (b) did not abolish CTA produced by 2 or 3 saccharin-LiCl pairings; (c) did not cause persistent increase of quinine threshold; and (d) elicited anterograde CTA amnesia when applied 1 but not 2, 4, or 8 days before CTA acquisition. TTX-induced amnesia is not due to persistent gustatory agnosia but rather to disruption of the protracted consolidation of the permanent CTA engram by prolonged cessation of impulse activity in the information storing network.

Animals↗
PubMed2003

Blood pressure relates to sodium taste sensitivity and discrimination in adolescents.

To investigate salt perception and discrimination and their possible association with blood pressure (BP), 72 healthy adolescents (42 boys) aged 9-21 years (mean 16.1 years) were studied. BP was measured with a standardized technique. Anthropometric measurement and conventional renal function tests were performed. Sensitivity tests to recognize the presence of salt when given simultaneously distilled/deionized water and a low sodium concentration water solution, and discrimination tests consisting of six graded samples of different saline solutions presented in randomized order were used to assess individual gustatory sensitivity. Average systolic BP values were 113.2+/-1.6 mmHg in boys and 109.6+/-1.9 mmHg in girls. Mean threshold level for salt sensitivity was 4.55+/-0.6 mmol/l. Systolic BP and salt sensitivity showed a significant correlation ( r=-0.33, P<0.01) even when adjusting for weight. Discrimination score was correlated with salt sensitivity ( r=0.27, P<0.05). There is a significant association between gustatory perception and BP in Spain adolescents, although a real cause-effect relationship has not been established.

Adolescent↗
PubMedDate not supplied

Effect of the nucleoside analogs zidovudine, didanosine, stavudine, and lamivudine on the sense of taste.

The purpose of this study was to investigate the taste properties of nucleoside analogs, which are among the current medications used to treat human immunodeficiency virus (HIV) infection. Eighteen unmedicated HIV-positive subjects and 41 healthy control subjects participated in threshold and suprathreshold experiments. All of the nucleoside medications tested were perceived as predominantly bitter (along with other qualities such as metallic, medicinal, sour, astringent, and cooling). The nucleoside analog with the lowest detection thresholds was zidovudine; the detection threshold was 1.47 mM for HIV-infected patients and 2.15 mM for control subjects. Detection thresholds for lamivudine were 4.41 mM for HIV-infected patients and 4.36 mM for control subjects. Detection thresholds for stavudine were 6.39 mM for HIV-infected patients and 5.99 mM for control subjects. Detection thresholds for didanosine were 14.29 mM for HIV-infected patients and 24.0 mM for control subjects. The nucleoside analogs also modified the taste perception of KCl and CaCl2. There were no significant differences between HIV-infected subjects and control subjects for detection threshold values for any of the drugs. However, HIV-infected subjects rated lamivudine, zidovudine, and stavudine as significantly more bitter than did the control subjects at concentrations four times higher than their detection thresholds. This result was not due to use of medications by HIV-infected subjects because none of the subjects (neither HIV-infected nor control) were taking medications.

Adult↗
PubMed1990

Responses from parabrachial gustatory neurons in behaving rats.

1. The responses of a total of 70 single neurons were recorded from the parabrachial nuclei (PBN) in awake rats. In 59 neurons, sapid stimuli (0.5 ml) elicited significant taste responses. Of these 59 neurons, 10 also had significant responses to water. The mean spontaneous rate of the taste neurons was 13.4 +/- 6.9 (SD) spikes/s. Of the remaining 11 neurons, 9 responded significantly only to water; 2 had no significant responses to the standard fluid stimuli. 2. Based on the magnitude of their response to our four standard stimuli, the taste neurons were classified as follows: 42 NaCl-best, 14 sucrose-best, 2 citric acid-best, and 1 QHCl-best. Of these, 25 responded only to one of four sapid stimuli; 20 of these specific cells responded only to NaCl. All the remaining 34 neurons responded to two or more of the four sapid stimuli, with NaCl and sucrose responsiveness dominant. For the 59 taste neurons, the mean entropy for the absolute value of the responses was 0.68; for the excitatory activity alone, it was 0.58. 3. The mean responses to NaCl and sucrose concentration series increased monotonically. Except at the lowest concentration, responses to citric acid also increased monotonically, but with a lower slope. Mean responses to QHCl, however, remained stable or even decreased with increasing concentration. Thus the power functions for the NaCl and sucrose intensity-response series were higher than those of citric acid and QHCl. 4. A hierarchical cluster analysis of 59 parabrachial neurons suggested four different categories: NaCl-best, sucrose-best, citric acid-best, and QHCl-best. These categories were less evident in the two-dimensional space produced by multidimensional analysis, because the positions of NaCl- and sucrose-best neurons formed a continuum in which neural response profiles change successively from sucrose-specific to NaCl-specific. 5. The results were consistent with previous anatomic and neurophysiological data suggesting convergence in the medulla of sensory input from receptors in the nasoincisor ducts (NID) and on the anterior tongue (AT). Taste buds in the NID respond preferentially to sucrose, whereas those on the AT respond more to NaCl.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed2000

Psychophysics of taste lateralization on anterior tongue.

There have been very few investigations of the spatial properties of taste stimuli localized to specific areas of the oral cavity. This is surprising, since the spatial localization of taste sensations may contribute to the overall taste percept, much as do quality, intensity, and the temporal characteristics of tastes. The difficulty in eliminating the confounding factor of a tactile sensation may partially account for the paucity of such studies, since a gustatory stimulus cannot be presented as a liquid without a tactile component. As a step toward understanding the localizability of gustatory sensations, we designed a yoked stimulator and an experimental procedure to control for tactile cues. Lateral discrimination was evaluated at the tip of the tongue with four taste stimuli (sodium saccharin, sodium chloride, citric acid, and quinine hydrochloride) by presenting a taste and a blank solution simultaneously at two locations on the tongue. We found that subjects could lateralize all four taste stimuli in the absence of any discriminative tactile cues. Subjects' ability to lateralize varied as a psychometric function of the stimulus concentration. Detection thresholds, measured in a forced-choice two-interval staircase procedure with the same yoked stimulator that was used in the lateralization task, were always lower than lateralization thresholds, and both lateralization and detection thresholds were correlated within subjects. Subjects were unable to lateralize taste cues on a nongustatory surface under the upper lip at the highest tested concentrations, at which performance was 100% on a gustatory surface (dorsal anterior tongue). These results show that (1) taste compounds can be lateralized in the absence of any discriminative mechanical cue (but only on the gustatory epithelium) and (2) although the localization of a compound does not logically require conscious detection of the taste (cf. blind sight), subjects always detected a taste when they were able to lateralize.

Adult↗
PubMed1988

Gustatory responsiveness of fibers in the hamster glossopharyngeal nerve.

1. Mammalian taste receptors are distributed within separate subpopulations, innervated by branches of cranial nerves VII, IX, and X. Most gustatory electrophysiology has focused on input from the fungiform papillae on the anterior portion of the tongue, carried by the chorda tympani branch of the VIIth nerve. However, only a small percentage of the taste buds are located in the fungiform papillae (approximately 18% in the hamster). There have been no studies on the hamster's IXth nerve, which innervates greater than 50% of its taste buds, and most other studies of IXth nerve function have employed only whole-nerve recording. 2. Action potentials were recorded from 83 individual fibers in the IXth nerve of the hamster. Stimuli were five concentrations each of sucrose, NaCl, HCl, and quinine hydrochloride (QHCl), all presented to every fiber at 37 degrees C. Responses were quantified as the number of impulses in 10 s minus the preceding 10 s of spontaneous activity. 3. Across these concentration series, HCl and QHCl were by far the most excitatory stimuli, with mean responses across all cells three to four times greater than those evoked by sucrose or NaCl. The order of effectiveness of the stimuli was H greater than Q much greater than N greater than S. 4. Of the 83 fibers, 56 were stimulated via the foliate papillae and 27 via the single vallate papilla. No fibers responded to both of these fields. There were generally no differences in the sensitivity of these two subpopulations of taste buds, except that QHCl was more effective when applied to the foliates. 5. A "total" response measure was derived by summing the excitatory responses to each stimulus across the entire concentration series. The fibers were then classified according to the best total response, resulting in 52 HCl-, 19 QHCl-, 8 sucrose- and 4 NaCl-best cells. Considering the slope of the concentration-response functions as a criterion for classification produced very similar results. The fiber classification varied somewhat with concentration, with more fibers categorized as HCl- and QHCl-best at the higher concentration levels. 6. Breadth of responsiveness was measured using the equation developed by Smith and Travers. At the concentrations used to examine hamster chorda tympani fibers, IXth nerve fibers were not very responsive and were quite narrowly tuned to the four taste qualities. At higher concentrations the fibers became more broadly responsive across the four stimuli.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗