Masking the Detection of Taste Stimuli in Rats: NaCl and Sucrose

Abstract While psychophysical and neurophysiological assessments of taste sensitivity to single chemical compounds have revealed some fundamental properties of gustatory processing, taste stimuli are rarely ingested in isolation. Arguably, the gustatory system was adapted to identify and report the presence of numerous chemicals ingested concurrently. To begin systematically exploring the detectability of a target stimulus in a background in rodents, we used a gustometer to train rats in a 2-response operant task to detect either NaCl (n = 8) or sucrose (n = 8) dissolved in water, and then tested the sensitivity of rats to the trained NaCl stimulus dissolved in a sucrose masker (0.3, 0.6, or 1.0 M, tested consecutively) versus sucrose, or the trained sucrose stimulus dissolved in a NaCl masker (0.04, 0.2, or 0.4 M) versus NaCl. Detection thresholds (EC50 values) were determined for the target stimulus dissolved in each concentration of the masker. Except for 0.04 M NaCl, all masker concentrations tested increased the target stimulus EC50. Target stimulus detectability decreased systematically as masker concentrations increased. The shift in liminal sensitivity for either target was similar when the threshold for the masker was considered. At least for these prototypical stimuli, it appears that the attenuating impact of a masker on the detection of a target stimulus depends on sensitivity to the masking stimulus. Further study will be required to generalize these results and extend them to more complex maskers, and to discern neural circuits involved in the detection of specific taste signals in the context of noisy backgrounds.

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Visual Masking with Presentations in Same and opposite Visual Fields: Evidence for Contralateral Masking

Perceptual and Motor Skills ◽

10.2466/pms.1982.55.1.131 ◽

1982 ◽

Vol 55 (1) ◽

pp. 131-140 ◽

Cited By ~ 6

Author(s):

Dennis P. Saccuzzo ◽

Brad E. Michael ◽

Robert Rowe

Keyword(s):

Visual Field ◽

Target Stimulus ◽

Visual Masking ◽

Visual Fields ◽

Right Visual Field ◽

Future Research ◽

Backward Masking ◽

Masking Stimulus ◽

The Right ◽

Contralateral Masking

Three experiments were conducted in a preliminary attempt to study the effects of presentations of an informational target stimulus to the right or left visual fields when the target was either preceded or followed by a non-informational masking stimulus and when the mask was presented to the same or opposite visual field of the target. Results indicated that masking was more effective in the same than in the opposite visual field but that masking of the opposite visual field was feasible for both forward and backward masking. Laterality effects were also found for forward and backward masking, with a modest advantage of the right visual field (left hemisphere) in both cases. Limitations of the data and directions for future research were discussed.

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The Functional and Neurobiological Properties of Bad Taste

Physiological Reviews ◽

10.1152/physrev.00044.2017 ◽

2019 ◽

Vol 99 (1) ◽

pp. 605-663 ◽

Cited By ~ 18

Author(s):

Lindsey A. Schier ◽

Alan C. Spector

Keyword(s):

Neural Circuits ◽

Mammalian Brain ◽

Gustatory System ◽

Biologically Relevant ◽

Neural Architecture ◽

Technological Advances ◽

Close Relationship ◽

The Brain ◽

Experimental Strategies

The gustatory system serves as a critical line of defense against ingesting harmful substances. Technological advances have fostered the characterization of peripheral receptors and have created opportunities for more selective manipulations of the nervous system, yet the neurobiological mechanisms underlying taste-based avoidance and aversion remain poorly understood. One conceptual obstacle stems from a lack of recognition that taste signals subserve several behavioral and physiological functions which likely engage partially segregated neural circuits. Moreover, although the gustatory system evolved to respond expediently to broad classes of biologically relevant chemicals, innate repertoires are often not in register with the actual consequences of a food. The mammalian brain exhibits tremendous flexibility; responses to taste can be modified in a specific manner according to bodily needs and the learned consequences of ingestion. Therefore, experimental strategies that distinguish between the functional properties of various taste-guided behaviors and link them to specific neural circuits need to be applied. Given the close relationship between the gustatory and visceroceptive systems, a full reckoning of the neural architecture of bad taste requires an understanding of how these respective sensory signals are integrated in the brain.

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Interference and visual masking

10.31234/osf.io/h8wcr ◽

2018 ◽

Author(s):

Bernt Skottun

Keyword(s):

Stimulus Onset Asynchrony ◽

Target Stimulus ◽

Visual Masking ◽

Temporal Integration ◽

Stimulus Onset ◽

Limited Extent ◽

Interference Effects ◽

Type B ◽

Masking Stimulus ◽

Onset Asynchrony

It is well known that a masking stimulus may reduce the visibility of a target stimulus. This has most commonly been attributed the mechanisms in the visual system. It has, however, become evident that a masking stimulus may reduce the stimulus power of a target. Such reductions which are in the stimuli have been explored in relation to spatial stimuli (Skottun, 2017, DOI:10.3758/s13428-017-0978-3; Skottun,2018. DOI: 10.1016/j.bbr.2018.04.016). An important aspect of visual masking is the effect of the relative temporal onset of the two stimuli (i.e., the Stimulus Onset Asynchrony, SOA). The present study sought to explore, using numerical analyses, how interference across time may manifest itself. By assuming some degree of temporal inaccuracy and a limited extent of temporal integration it was found that, depending on conditions, interference effects may take on the characteristics of either Type-A or Type-B masking. In connection with visual masking it is (tacitly) assumed that the target stimulus has the same stimulus power when presented in combination with a masking stimulus presented as when presented alone. It has earlier been shown that this cannot be assumed in connection with spatial stimuli. The present analyses make clear that this may also apply to stimuli presented at somewhat different times.

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Taste sensitivity to a mixture of monosodium glutamate and inosine 5′-monophosphate by mice lacking both subunits of the T1R1+T1R3 amino acid receptor

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00352.2017 ◽

2018 ◽

Vol 314 (6) ◽

pp. R802-R810 ◽

Cited By ~ 2

Author(s):

Ginger D. Blonde ◽

Susan P. Travers ◽

Alan C. Spector

Keyword(s):

Compound Stimulus ◽

Allelic Variation ◽

Monosodium Glutamate ◽

Taste Sensitivity ◽

Receptor Subunit ◽

Wild Type ◽

Independent Mechanism ◽

Limited Degree ◽

Operant Task ◽

High Concentrations

The taste of l-glutamate and its synergism with 5′-ribonucleotides is thought to be primarily mediated through the T1R1+T1R3 heterodimer in some mammals, including rodents and humans. While knockout (KO) mice lacking either receptor subunit show impaired sensitivity to a range of monosodium glutamate (MSG) concentrations mixed with 2.5 mM inosine 5′-monophosphate (IMP) in amiloride, wild-type (WT) controls can detect this IMP concentration, hindering direct comparison between genotypes. Moreover, some residual sensitivity persists in the KO group, suggesting that the remaining subunit could maintain a limited degree of function. Here, C57BL/6J, 129X1/SvJ, and T1R1+T1R3 double KO mice ( n = 16 each to start the experiment) were trained in a two-response operant task in gustometers and then tested for their ability to discriminate 100 µM amiloride from MSG (starting with 0.6 M) and IMP (starting with 2.5 mM) in amiloride (MSG+I+A). Testing continued with successive dilutions of both MSG and IMP (in amiloride). The two WT strains were similarly sensitive to MSG+I+A ( P > 0.8). KO mice, however, were significantly impaired relative to either WT strain ( P < 0.01), although they were able to detect the highest concentrations. Thus, normal detectability of MSG+I+A requires an intact T1R1+T1R3 receptor, without regard for allelic variation in the T1R3 gene between the WT strains. Nevertheless, residual sensitivity by the T1R1+T1R3 KO mice demonstrates that a T1R-independent mechanism can contribute to the detectability of high concentrations of this prototypical umami compound stimulus.

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FACTORS AFFECTING THE VIABILITY OF AIR-BORNE BACTERIA: II. THE EFFECT OF CHEMICAL ADDITIVES ON THE BEHAVIOR OF AIR-BORNE CELLS

Canadian Journal of Microbiology ◽

10.1139/m60-010 ◽

1960 ◽

Vol 6 (1) ◽

pp. 71-87 ◽

Cited By ~ 30

Author(s):

S. J. Webb

Keyword(s):

Secondary Alcohol ◽

Chemical Compounds ◽

Pyrimidine Ring ◽

Hydroxyl Group ◽

Bacterial Suspension ◽

Chemical Additives ◽

Large Measure ◽

Alcohol Group ◽

Factors Affecting ◽

Single Chemical

The effect on air-borne cells of single chemical compounds added to a bacterial suspension prior to atomization has been studied. It has been found that some amino acids, long chain protein degredates, some sugars and polyhydroxycyclohexanes can enhance the survival of air-borne cells. The ability of a compound to preserve viability during periods of desiccation has been found to be connected with the presence of an amino and/or secondary alcohol group. For maximal protection these groups need to be substituted onto a six-membered ring nucleus. The hydroxyl group has been found toxic if present on a benzene ring, but protective on a pyrimidine ring. Inositol was found to afford a large measure of stability to the air-borne cells and its stabilizing ability could be destroyed by urea and guanidine. It is suggested that compounds enhance survival by replacing water molecules in protein structure during desiccation through hydrogen bonding and so preserve the natural structure of the cellular proteins. Peaks in death rates at intermediate relative humidity levels have been found to be due to the presence of the added compounds.

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Metacontrast, target recovery, and the magno- and parvocellular systems: A perspective

Visual Neuroscience ◽

10.1017/s0952523807070228 ◽

2007 ◽

Vol 24 (2) ◽

pp. 177-181 ◽

Cited By ~ 9

Author(s):

BERNT C. SKOTTUN ◽

JOHN R. SKOYLES

Keyword(s):

Time Course ◽

Target Stimulus ◽

Masking Effect ◽

Magnocellular System ◽

Target Recovery ◽

Masking Stimulus

In metacontrast a masking stimulus reduces the visibility of an adjacent target stimulus. This effect has been interpreted in terms of magno-/parvocellular interactions. It has also been found that a second masking stimulus, which precedes the primary mask by about 90 ms reduces the masking effect. This reduction, which is termed “target recovery,” has been hypothesized to reflect parvocellular inhibition of the magnocellular system. However, this is problematic because the time course of this effect is much larger than would be expected from magno-/parvocellular interactions. For this and other reasons, it is difficult to understand metacontrast in terms of magno- and parvocellular mechanisms.

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Responses of single hamster parabrachial neurons to binary taste mixtures of citric acid with sucrose or NaCl

Journal of Neurophysiology ◽

10.1152/jn.1993.70.4.1350 ◽

1993 ◽

Vol 70 (4) ◽

pp. 1350-1364 ◽

Cited By ~ 14

Author(s):

M. B. Vogt ◽

D. V. Smith

Keyword(s):

Citric Acid ◽

Binary Mixtures ◽

The Other ◽

Gustatory System ◽

Behavioral Measures ◽

Strong Concentration ◽

Neurophysiological Studies ◽

Single Chemical ◽

Mixture Suppression ◽

Effective Component

1. Although taste experience generally arises from a mixture of gustatory stimuli, most neurophysiological studies of the mammalian central gustatory system have focused on responses to single chemical stimuli. Recently, in a study of single third-order neurons in the hamster parabrachial nucleus (PbN), we reported that mixture suppression occurs in the responses to binary mixtures of sucrose and QHCl presented to the anterior tongue. Mixture suppression was reflected both in reduced response frequencies and in an altered pattern of responses across neurons. In the current report we extend our investigation of CNS neuron responses to binary mixtures of heterogeneous stimuli to include sucrose+citric acid mixtures and NaCl+citric acid mixtures. The response to each mixture was compared with the response to the more effective component (MEC) presented alone, and those that differed by more than a selected criterion (based on response variability) were identified. 2. For all mixture responses recorded, 29% (79/256) involved mixture suppression (mixture response < MEC response), only 6% (18/276) were greater than the response to MEC, and 65% (179/276) did not differ from the response to the MEC. 3. In Experiments 1 and 2, neurons were tested with four concentrations of sucrose or citric acid each presented alone and in binary mixtures with a single strong concentration of the other stimulus. Sucrose suppression (mixture response < sucrose response) occurred in 24% of mixture responses and was exhibited almost exclusively by sucrose-best neurons, primarily to the mixtures that contained the stronger sucrose and citric acid concentrations. Sucrose suppression involved a 40% reduction of mixture response frequencies compared with responses to the sucrose component alone. 4. In Experiments 3 and 4, neurons were tested with four concentrations of NaCl or citric acid each presented alone and in binary mixtures with a single strong concentration of the other stimulus. NaCl suppression (mixture response < NaCl response) occurred in 21% of mixture responses and was displayed by both sucrose-best and NaCl-best neurons. NaCl suppression involved a 28% reduction in mixture response frequencies compared with responses to the NaCl component alone. In all experiments citric acid suppression (mixture response < citric acid response) was observed in only 6% of mixture responses and was relatively small in magnitude. 5. The across-neuron patterns (ANPs) of taste responses, which are correlated with behavioral measures of taste similarity, were compared for mixtures and components.(ABSTRACT TRUNCATED AT 400 WORDS)

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Responses of single hamster parabrachial neurons to binary taste mixtures: mutual suppression between sucrose and QHCl

Journal of Neurophysiology ◽

10.1152/jn.1993.69.3.658 ◽

1993 ◽

Vol 69 (3) ◽

pp. 658-668 ◽

Cited By ~ 31

Author(s):

M. B. Vogt ◽

D. V. Smith

Keyword(s):

Response Magnitude ◽

Gustatory System ◽

Third Order ◽

Neurophysiological Studies ◽

Single Chemical ◽

Chemical Stimuli ◽

Mixture Suppression ◽

Effective Component ◽

Extracellular Activity ◽

Taste Experience

1. Although taste experience typically arises from a mixture of gustatory stimuli, nearly all previous neurophysiological studies of the mammalian central gustatory system have focused on responses to single chemical stimuli. To begin to systematically examine CNS responses to taste mixtures, we recorded the extracellular activity of single third-order neurons in the hamster PbN to anterior tongue stimulation with binary mixtures of sucrose and QHCl. In experiment 1, neurons were tested with four concentrations of sucrose (0.001, 0.01, and 1.0 M) presented alone and mixed with 0.1 M QHCl. In experiment 2, neurons were tested with four concentrations of QHCl (0.00032, 0.0032, 0.032, and 0.1 M) presented alone and mixed with 1.0 M sucrose. 2. The response to each binary mixture was compared with the response to the more effective component (MEC) presented alone, and those that differed by more than a selected criterion (based on response variability) were identified. Of all mixture responses, 37% (59/158) involved mixture suppression (mixture response < MEC response), only 4% (6/158) were greater than the MEC, and 59% (94/158) were classified as not different than the response to the MEC. Most neurons that displayed mixture suppression did so at several mixture concentrations. 3. Sucrose suppression (mixture response < sucrose response) was prevalent among neurons most responsive to sucrose and for the mixtures that contained the stronger sucrose concentrations. Among neurons that displayed sucrose suppression, the magnitude of suppression was significantly correlated with sucrose response magnitude but not with QHCl response magnitude. These and other factors suggest that a neuron's capacity to display sucrose suppression to sucrose+QHCl mixtures is related to its sucrose sensitivity. 4. QHCl suppression (mixture response < QHCl response) was less prevalent than sucrose suppression, and the neurons that displayed QHCl suppression were almost exclusively a subset of those that displayed sucrose suppression to the same or different mixtures. This finding and the observation that one-third of all mixture responses involved mutual suppression (response to the mixture less than that to either component alone), suggest an association between the factors underlying sucrose suppression and QHCl suppression. 5. The across-neuron patterns (ANPs) of taste responses, which are thought to represent taste quality, were compared for mixtures and components. In general, the ANP for each mixture was similar to (significantly correlated with) the ANP of the more stimulatory component. However, for the mixture that evoked the greatest sucrose suppression, the mixture ANP was more similar to the ANP of the less stimulatory component.(ABSTRACT TRUNCATED AT 400 WORDS)

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Neurophysiological and Behavioral Analysis in Xenopus

Cold Spring Harbor Protocols ◽

10.1101/pdb.top106849 ◽

2021 ◽

Vol 2021 (11) ◽

pp. pdb.top106849

Author(s):

Ben G. Szaro

Keyword(s):

Gene Expression ◽

Optic Tectum ◽

Neural Circuits ◽

Neural Circuitry ◽

Behavioral Analysis ◽

Fundamental Properties ◽

Locomotory Behavior ◽

Electrophysiological Studies ◽

Ready Availability ◽

External Development

Because of its resilience to hypoxia and trauma, the frog has long been a favored preparation of neurophysiologists. Its use has led to the discovery of many fundamental properties of neurons and neural circuits. Neurophysiologists were originally attracted to Xenopus embryos, tadpoles, and frogs because of their ready availability, their external development, and the anatomical accessibility and relatively simple neural circuitry of the Xenopus visual, locomotory, and vocalization systems. Nowadays, the sequencing of Xenopus genomes and the panoply of tools for manipulating gene expression have created new opportunities for neurophysiologists to address the molecular underpinnings of how neurons generate behaviors in a vertebrate. Here, we introduce protocols for harnessing the power of Xenopus for performing electrophysiological studies of neural circuitry in the developing optic tectum and spinal cord, as well as in vocalization, and for studying the ontogeny of locomotory behavior.

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