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Tsou JH, Lee SR, Chiang CY, Yang YJ, Guo FY, Ni SY, Yau HJ. Negative Emotions Recruit the Parabrachial Nucleus Efferent to the VTA to Disengage Instrumental Food Seeking. J Neurosci 2023; 43:7276-7293. [PMID: 37684032 PMCID: PMC10621778 DOI: 10.1523/jneurosci.2114-22.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 08/14/2023] [Accepted: 08/29/2023] [Indexed: 09/10/2023] Open
Abstract
The parabrachial nucleus (PBN) interfaces between taste and feeding systems and is also an important hub for relaying distress information and threats. Despite that the PBN sends projections to the ventral tegmental area (VTA), a heterogeneous brain region that regulates motivational behaviors, the function of the PBN-to-VTA connection remains elusive. Here, by using male mice in several behavioral paradigms, we discover that VTA-projecting PBN neurons are significantly engaged in contextual fear, restraint or mild stress but not palatable feeding, visceral malaise, or thermal pain. These results suggest that the PBN-to-VTA input may relay negative emotions under threat. Consistent with this notion, optogenetic activation of PBN-to-VTA glutamatergic input results in aversion, which is sufficient to override palatable feeding. Moreover, in a palatable food-reinforced operant task, we demonstrate that transient optogenetic activation of PBN-to-VTA input during food reward retrieval disengages instrumental food-seeking behaviors but spares learned action-outcome association. By using an activity-dependent targeting approach, we show that VTA DA neurons are disengaged by the PBN afferent activation, implicating that VTA non-DA neurons may mediate PBN afferent regulation. We further show that optogenetic activation of VTA neurons functionally recruited by the PBN input results in aversion, dampens palatable feeding, and disengages palatable food self-administration behavior. Finally, we demonstrate that transient activation of VTA glutamatergic, but not GABAergic, neurons recapitulates the negative regulation of the PBN input on food self-administration behavior. Together, we reveal that the PBN-to-VTA input conveys negative affect, likely through VTA glutamatergic neurons, to disengage instrumental food-seeking behaviors.SIGNIFICANCE STATEMENT The PBN receives multiple inputs and thus is well positioned to route information of various modalities to engage different downstream circuits to attend or respond accordingly. We demonstrate that the PBN-to-VTA input conveys negative affect and then triggers adaptive prioritized responses to address pertinent needs by withholding ongoing behaviors, such as palatable food seeking or intake shown in the present study. It has evolutionary significance because preparing to cope with stressful situations or threats takes priority over food seeking to promote survival. Knowing how appropriate adaptive responses are generated will provide new insights into circuitry mechanisms of various coping behaviors to changing environmental stimuli.
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Affiliation(s)
- Jen-Hui Tsou
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan
- Synaptic Plasticity Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224
| | - Syun-Ruei Lee
- Laboratory for Neural Circuits and Behaviors, Graduate Institute of Brain and Mind Sciences, National Taiwan University, Taipei 10051, Taiwan
| | - Chia-Ying Chiang
- Laboratory for Neural Circuits and Behaviors, Graduate Institute of Brain and Mind Sciences, National Taiwan University, Taipei 10051, Taiwan
| | - Yi-Jie Yang
- Laboratory for Neural Circuits and Behaviors, Graduate Institute of Brain and Mind Sciences, National Taiwan University, Taipei 10051, Taiwan
| | - Fong-Yi Guo
- Laboratory for Neural Circuits and Behaviors, Graduate Institute of Brain and Mind Sciences, National Taiwan University, Taipei 10051, Taiwan
| | - Shih-Ying Ni
- School of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Hau-Jie Yau
- Laboratory for Neural Circuits and Behaviors, Graduate Institute of Brain and Mind Sciences, National Taiwan University, Taipei 10051, Taiwan
- Neurobiology and Cognitive Science Center, National Taiwan University, Taipei 10617, Taiwan
- Taiwan International Graduate Program in Interdisciplinary Neuroscience, National Taiwan University and Academia Sinica, Taipei 115, Taiwan
- PhD Program in Translational Medicine, National Taiwan University and Academia Sinica, Taipei 115, Taiwan
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2
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Nakajima KI. Neural insights into sweet taste transduction and hunger-induced taste modification in mice. Biosci Biotechnol Biochem 2022; 86:1485-1489. [PMID: 35998309 DOI: 10.1093/bbb/zbac142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 08/14/2022] [Indexed: 11/14/2022]
Abstract
Feeding is one of the most fundamental activities in the survival and reproduction of animals. During feeding, the gustatory system functions as a gate keeper to evaluate food quality. Accumulated evidence in the field of taste research has shown that five basic tastes (sweet, umami, sour, bitter, and salty) are sensed by the corresponding taste receptors expressed in taste receptor cells on the tongue. In contrast, brain mechanisms that transduce or modify taste information have been less studied. In this review, I introduce our recent findings on the sweet taste transduction in the brainstem of mice and explain the hypothalamic neuronal network regulating hunger-induced taste modification. Finally, future perspectives are discussed.
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Affiliation(s)
- Ken-Ichiro Nakajima
- Division of Endocrinology and Metabolism, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi, Japan.,Department of Physiological Sciences, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi, Japan
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3
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Yoshida M, Chinzorig C, Matsumoto J, Nishimaru H, Ono T, Yamazaki M, Nishijo H. Configural Cues Associated with Reward Elicit Theta Oscillations of Rat Retrosplenial Cortical Neurons Phase-Locked to LFP Theta Cycles. Cereb Cortex 2021; 31:2729-2741. [PMID: 33415336 DOI: 10.1093/cercor/bhaa395] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Previous behavioral studies implicated the retrosplenial cortex (RSC) in stimulus-stimulus associations, and also in the retrieval of remote associative memory based on EEG theta oscillations. However, neural mechanisms involved in the retrieval of stored information of such associations and memory in the RSC remain unclear. To investigate the neural mechanisms underlying these processes, RSC neurons and local field potentials (LFPs) were simultaneously recorded from well-trained rats performing a cue-reward association task. In the task, simultaneous presentation of two multimodal conditioned stimuli (configural CSs) predicted a reward outcome opposite to that associated with the individual presentation of each elemental CS. Here, we show neurophysiological evidence that the RSC is involved in stimulus-stimulus association where configural CSs are discriminated from each elementary CS that is a constituent of the configural CSs, and that memory retrieval of rewarding CSs is associated with theta oscillation of RSC neurons during CS presentation, which is phase-locked to LFP theta cycles. The results suggest that cue (elementary and configural CSs)-reinforcement associations are stored in the RSC neural circuits, and are retrieved in synchronization with LFP theta rhythm.
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Affiliation(s)
- Masashi Yoshida
- Department of Anesthesiology, Faculty of Medicine, University of Toyama, Toyama 930-0194, Japan
| | - Choijiljav Chinzorig
- Department of System Emotional Science, Faculty of Medicine, University of Toyama, Toyama 930-0194, Japan.,Department of Physiology, School of Bio-medicine, Mongolian National University of Medical Sciences, Ulaanbaatar 14210, Mongolia
| | - Jumpei Matsumoto
- Department of System Emotional Science, Faculty of Medicine, University of Toyama, Toyama 930-0194, Japan
| | - Hiroshi Nishimaru
- Department of System Emotional Science, Faculty of Medicine, University of Toyama, Toyama 930-0194, Japan.,Graduate School of Innovative Life Science, University of Toyama, Toyama 930-0194, Japan.,Research Center for Idling Brain Science (RCIBS), University of Toyama, Toyama 930-0194, Japan
| | - Taketoshi Ono
- Department of System Emotional Science, Faculty of Medicine, University of Toyama, Toyama 930-0194, Japan
| | - Mitsuaki Yamazaki
- Department of Anesthesiology, Faculty of Medicine, University of Toyama, Toyama 930-0194, Japan
| | - Hisao Nishijo
- Department of System Emotional Science, Faculty of Medicine, University of Toyama, Toyama 930-0194, Japan.,Graduate School of Innovative Life Science, University of Toyama, Toyama 930-0194, Japan.,Research Center for Idling Brain Science (RCIBS), University of Toyama, Toyama 930-0194, Japan
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4
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Munkhzaya U, Chinzorig C, Matsumoto J, Nishimaru H, Ono T, Nishijo H. Rat Paraventricular Neurons Encode Predictive and Incentive Information of Reward Cues. Front Behav Neurosci 2020; 14:565002. [PMID: 33033475 PMCID: PMC7509094 DOI: 10.3389/fnbeh.2020.565002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Accepted: 08/14/2020] [Indexed: 12/24/2022] Open
Abstract
The paraventricular nucleus of the thalamus (PVT) has been implicated in cue-induced motivated behaviors. Although reward-associated cues (conditioned stimuli, CSs) contain different types of information including predictive information of future reward delivery and incentive (motivational) value of the reward, it remains unknown whether PVT neurons represent predictive and incentive information of CSs. It is suggested that neural activity just after the onset of CSs (early activity) and that just before reward delivery (late activity) might more strongly represent predictive and incentive information, respectively. In this study, rats were trained to lick a tube, which was protruded close to their mouth just after a CS, to obtain a reward (sucrose or water) (cue-induced licking task). Auditory and visual CSs were used: each elemental cue (CS) predicted reward or non-reward outcome, while simultaneous presentation of the two elemental cues (configural cues) predicted the opposite reward outcome. We recorded PVT neurons in the cue-induced licking task, and report that half of the CS-responsive PVT neurons responded selectively to the CSs predicting reward outcome regardless of physical property of the cues (CS+-selective). In addition, the early activity of the CS+-selective neurons discriminated reward/non-reward association (predictive information) and was less sensitive to reward value and motivation reflected by lick latency (incentive information), while the late activity of the CS+-selective neurons was correlated with reward value and motivation rather than reward/non-reward association. Early and late population activity of the CS+-selective neurons also represented predictive and incentive information of the CSs, respectively. On the other hand, activity of more than half of the PVT neurons was correlated with individual licking during licking to acquire reward. Taken together, the results suggest that the PVT neurons engage in different neural processes involved in cue-induced motivated behaviors: CS encoding to determine reward availability and form motivation for reward-seeking behavior, and hedonic mouth movements during reward consumption.
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Affiliation(s)
- Unur Munkhzaya
- System Emotional Science, Faculty of Medicine, University of Toyama, Toyama, Japan
| | - Choijiljav Chinzorig
- System Emotional Science, Faculty of Medicine, University of Toyama, Toyama, Japan
- Department of Physiology, School of Bio-Medicine, Mongolian National University of Medical Sciences, Ulaanbaatar, Mongolia
| | - Jumpei Matsumoto
- System Emotional Science, Faculty of Medicine, University of Toyama, Toyama, Japan
- Research Center for Idling Brain Science (RCIBS), University of Toyama, Toyama, Japan
| | - Hiroshi Nishimaru
- System Emotional Science, Faculty of Medicine, University of Toyama, Toyama, Japan
- Research Center for Idling Brain Science (RCIBS), University of Toyama, Toyama, Japan
| | - Taketoshi Ono
- System Emotional Science, Faculty of Medicine, University of Toyama, Toyama, Japan
| | - Hisao Nishijo
- System Emotional Science, Faculty of Medicine, University of Toyama, Toyama, Japan
- Research Center for Idling Brain Science (RCIBS), University of Toyama, Toyama, Japan
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Fu O, Iwai Y, Kondoh K, Misaka T, Minokoshi Y, Nakajima KI. SatB2-Expressing Neurons in the Parabrachial Nucleus Encode Sweet Taste. Cell Rep 2020; 27:1650-1656.e4. [PMID: 31067452 DOI: 10.1016/j.celrep.2019.04.040] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 03/12/2019] [Accepted: 04/08/2019] [Indexed: 12/21/2022] Open
Abstract
The gustatory system plays an important role in sensing appetitive and aversive tastes for evaluating food quality. In mice, taste signals are relayed by multiple brain regions, including the parabrachial nucleus (PBN) of the pons, before reaching the gustatory cortex via the gustatory thalamus. Recent studies show that taste information at the periphery is encoded in a labeled-line manner, such that each taste modality has its own receptors and neuronal pathway. In contrast, the molecular identity of gustatory neurons in the CNS remains unknown. Here, we show that SatB2-expressing neurons in the PBN play a pivotal role in sweet taste transduction. With cell ablation, in vivo calcium imaging, and optogenetics, we reveal that SatB2PBN neurons encode positive valance and selectively transmit sweet taste signals to the gustatory thalamus.
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Affiliation(s)
- Ou Fu
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan; Division of Endocrinology and Metabolism, National Institute for Physiological Sciences, Okazaki, Aichi, Japan
| | - Yuu Iwai
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Kunio Kondoh
- Division of Endocrinology and Metabolism, National Institute for Physiological Sciences, Okazaki, Aichi, Japan; Department of Physiological Sciences, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi, Japan
| | - Takumi Misaka
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Yasuhiko Minokoshi
- Division of Endocrinology and Metabolism, National Institute for Physiological Sciences, Okazaki, Aichi, Japan; Department of Physiological Sciences, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi, Japan
| | - Ken-Ichiro Nakajima
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan; Division of Endocrinology and Metabolism, National Institute for Physiological Sciences, Okazaki, Aichi, Japan; Department of Physiological Sciences, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi, Japan.
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6
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Blonde GD, Spector AC. Masking the Detection of Taste Stimuli in Rats: NaCl and Sucrose. Chem Senses 2020; 45:359-370. [PMID: 32227159 DOI: 10.1093/chemse/bjaa022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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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Affiliation(s)
- Ginger D Blonde
- Department of Psychology and Program in Neuroscience, Florida State University, 1107 W. Call St., Tallahassee, FL, USA
| | - Alan C Spector
- Department of Psychology and Program in Neuroscience, Florida State University, 1107 W. Call St., Tallahassee, FL, USA
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Lundy R. Comparison of GABA, Somatostatin, and Corticotrophin-Releasing Hormone Expression in Axon Terminals That Target the Parabrachial Nucleus. Chem Senses 2020; 45:275-282. [PMID: 32107535 DOI: 10.1093/chemse/bjaa010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Several forebrain areas have been shown to project to the parabrachial nucleus (PBN) and exert inhibitory and excitatory influences on taste processing. Some sources of descending input such as the central nucleus of the amygdala (CeA) might utilize somatostatin (Sst) and/or corticotrophin-releasing hormone (Crh) to influence taste processing in the PBN (Panguluri S, Saggu S, Lundy R. 2009. Comparison of somatostatin and corticotrophin-releasing hormone immunoreactivity in forebrain neurons projecting to taste-responsive and non-responsive regions of the parabrachial nucleus in rat. Brain Res 1298:57-69; Magableh A, Lundy R. 2014. Somatostatin and corticotrophin releasing hormone cell types are a major source of descending input from the forebrain to the parabrachial nucleus in mice. Chem Senses 39:673-682). Since the predominate effect of CeA stimulation on PBN taste-evoked responses is inhibition, this study used transgenic reporter lines (Sst/TdTomato and Crh/TdTomato) and electron microscopy to assess Sst/gamma aminobutyric acid (GABA) and Crh/GABA coexpression in axon terminals within the PBN. Robust expression of Sst and Crh axon terminals was observed in the PBN. The majority of Sst-positive axon terminals were positive for GABA expression, while the majority of Crh terminals were not. The results indicate that Sst-expressing neurons, but not Crh neurons, are a source of GABAergic input to the PBN. To assess whether the CeA is a source of GABAergic input to the PBN, the CeA of Sst-cre mice was injected with cre-dependent enhanced yellow fluorescent protein (EYFP) virus and PBN tissue processed for GABA and EYFP expression. Again, the majority of EYFP Sst-positive axon terminals in the PBN coexpressed GABA. Together, the present results suggest that CeA neurons marked by Sst expression represent a major extrinsic source of GABAergic input to the PBN and this could underlie the predominate inhibitory effect of CeA stimulation on taste-evoked responses in the PBN.
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Affiliation(s)
- Robert Lundy
- Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, 500 South Preston St., HSC A, rm 1003, Louisville, KY, USA
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Rodriguez E, Sakurai K, Xu J, Chen Y, Toda K, Zhao S, Han BX, Ryu D, Yin H, Liedtke W, Wang F. A craniofacial-specific monosynaptic circuit enables heightened affective pain. Nat Neurosci 2017; 20:1734-1743. [PMID: 29184209 PMCID: PMC5819335 DOI: 10.1038/s41593-017-0012-1] [Citation(s) in RCA: 130] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 09/22/2017] [Indexed: 01/19/2023]
Abstract
Humans often rank craniofacial pain as more severe than body pain. Evidence suggests that a stimulus of the same intensity induces stronger pain in the face than in the body. However, the underlying neural circuitry for the differential processing of facial versus bodily pain remains unknown. Interestingly, the lateral parabrachial nucleus (PBL), a critical node in the affective pain circuit, is activated more strongly by noxious stimulation of the face than of the hindpaw. Using a novel activity-dependent technology called CANE developed in our laboratory, we identified and selectively labeled noxious-stimulus-activated PBL neurons and performed comprehensive anatomical input-output mapping. Surprisingly, we uncovered a hitherto uncharacterized monosynaptic connection between cranial sensory neurons and the PBL-nociceptive neurons. Optogenetic activation of this monosynaptic craniofacial-to-PBL projection induced robust escape and avoidance behaviors and stress calls, whereas optogenetic silencing specifically reduced facial nociception. The monosynaptic circuit revealed here provides a neural substrate for heightened craniofacial affective pain.
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Affiliation(s)
- Erica Rodriguez
- Department of Neurobiology, Duke University Medical Center, Durham, NC, USA
| | - Katsuyasu Sakurai
- Department of Neurobiology, Duke University Medical Center, Durham, NC, USA
| | - Jennie Xu
- Department of Neurobiology, Duke University Medical Center, Durham, NC, USA
| | - Yong Chen
- Department of Neurology, Duke University Medical Center, Durham, NC, USA
| | - Koji Toda
- Department of Psychology and Neuroscience, Duke University, Durham, NC, USA
| | - Shengli Zhao
- Department of Neurobiology, Duke University Medical Center, Durham, NC, USA
| | - Bao-Xia Han
- Department of Neurobiology, Duke University Medical Center, Durham, NC, USA
| | - David Ryu
- Department of Neurobiology, Duke University Medical Center, Durham, NC, USA
| | - Henry Yin
- Department of Psychology and Neuroscience, Duke University, Durham, NC, USA
| | - Wolfgang Liedtke
- Department of Neurology, Duke University Medical Center, Durham, NC, USA
| | - Fan Wang
- Department of Neurobiology, Duke University Medical Center, Durham, NC, USA.
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Schier LA, Spector AC. Post-oral sugar detection rapidly and chemospecifically modulates taste-guided behavior. Am J Physiol Regul Integr Comp Physiol 2016; 311:R742-R755. [PMID: 27511277 DOI: 10.1152/ajpregu.00155.2016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 08/03/2016] [Indexed: 12/31/2022]
Abstract
Several recent studies have shown that post-oral sugar sensing rapidly stimulates ingestion. Here, we explored the specificity with which early-phase post-oral sugar sensing influenced ingestive motivation. In experiment 1, rats were trained to associate the consumption of 0.3 M sucrose with injections of LiCl (3.0 meq/kg ip, conditioned taste aversion) or given equivalent exposures to the stimuli, but in an unpaired fashion. Then, all rats were subjected to two brief-access tests to assess appetitive and consummatory responses to the taste properties of sucrose (0.01-1.0 M), 0.12 M NaCl, and dH2O (in 10-s trials in randomized blocks). Intraduodenal infusions of either 0.3 M sucrose or equiosmolar 0.15 M NaCl (3.0 ml) were administered, beginning just before each test. For unpaired rats, intraduodenal sucrose specifically enhanced licking for 0.03-1.0 M sucrose, with no effect on trial initiation, relative to intraduodenal NaCl. Rats with an aversion to sucrose suppressed licking responses to sucrose in a concentration-dependent manner, as expected, but the intraduodenal sucrose preload did not appear to further influence licking responses; instead, intraduodenal sucrose attenuated trial initiation. Using a serial taste reactivity (TR) paradigm, however, experiment 2 demonstrated that intraduodenal sucrose preloads suppressed ingestive oromotor responses to intraorally delivered sucrose in rats with a sucrose aversion. Finally, experiment 3 showed that intraduodenal sucrose preloads enhanced preferential licking to some representative tastants tested (sucrose, Polycose, and Intralipid), but not others (NaCl, quinine). Together, the results suggest that the early phase-reinforcing efficacy of post-oral sugar is dependent on the sensory and motivational properties of the ingesta.
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Affiliation(s)
- Lindsey A Schier
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, Florida
| | - Alan C Spector
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, Florida
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10
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Baez-Santiago MA, Reid EE, Moran A, Maier JX, Marrero-Garcia Y, Katz DB. Dynamic taste responses of parabrachial pontine neurons in awake rats. J Neurophysiol 2016; 115:1314-23. [PMID: 26792879 DOI: 10.1152/jn.00311.2015] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 12/02/2015] [Indexed: 12/29/2022] Open
Abstract
The parabrachial nuclei of the pons (PbN) receive almost direct input from taste buds on the tongue and control basic taste-driven behaviors. Thus it is reasonable to hypothesize that PbN neurons might respond to tastes in a manner similar to that of peripheral receptors, i.e., that these responses might be narrow and relatively "dynamics free." On the other hand, the majority of the input to PbN descends from forebrain regions such as gustatory cortex (GC), which processes tastes with "temporal codes" in which firing reflects first the presence, then the identity, and finally the desirability of the stimulus. Therefore a reasonable alternative hypothesis is that PbN responses might be dominated by dynamics similar to those observed in GC. Here we examined simultaneously recorded single-neuron PbN (and GC) responses in awake rats receiving exposure to basic taste stimuli. We found that pontine taste responses were almost entirely confined to canonically identified taste-PbN (t-PbN). Taste-specificity was found, furthermore, to be time varying in a larger percentage of these t-PbN responses than in responses recorded from the tissue around PbN (including non-taste-PbN). Finally, these time-varying properties were a good match for those observed in simultaneously recorded GC neurons-taste-specificity appeared after an initial nonspecific burst of action potentials, and palatability emerged several hundred milliseconds later. These results suggest that the pontine taste relay is closely allied with the dynamic taste processing performed in forebrain.
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Affiliation(s)
- Madelyn A Baez-Santiago
- Biology Department, Brandeis University, Waltham, Massachusetts; Volen National Center for Complex Systems, Brandeis University, Waltham, Massachusetts;
| | - Emily E Reid
- Psychology Department, Brandeis University, Waltham, Massachusetts
| | - Anan Moran
- Psychology Department, Brandeis University, Waltham, Massachusetts; Volen National Center for Complex Systems, Brandeis University, Waltham, Massachusetts; Department of Neurobiology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel; Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel; and
| | - Joost X Maier
- Department of Neurobiology and Anatomy, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | | | - Donald B Katz
- Biology Department, Brandeis University, Waltham, Massachusetts; Psychology Department, Brandeis University, Waltham, Massachusetts; Volen National Center for Complex Systems, Brandeis University, Waltham, Massachusetts
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11
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Magableh A, Lundy R. Somatostatin and corticotrophin releasing hormone cell types are a major source of descending input from the forebrain to the parabrachial nucleus in mice. Chem Senses 2014; 39:673-82. [PMID: 25086873 DOI: 10.1093/chemse/bju038] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The pontine parabrachial nucleus (PBN) receives substantial descending input from higher order forebrain regions that exerts inhibitory and excitatory influences on taste-evoked responses. Somatostatin (Sst) and corticotrophin releasing hormone (Crh) reporter mice were used in conjunction with injection of the retrograde tracer CTb-488 into the caudal PBN to determine the extent to which Sst and Crh cell types contribute to the descending pathways originating in the lateral hypothalamus (LH), central nucleus of the amygdala (CeA), bed nucleus of the stria terminalis (BNST), and insular cortex (IC). Five to 7 days following injections, the animals were euthanized and tissue sections prepared for confocal microscopy. Crh cell types in each forebrain site except IC project to the PBN with the greatest percentage originating in the BNST. For Sst cell types, the largest percentage of double-labeled cells was found in the CeA followed by the BNST. Few retrogradely labeled cells in the LH coexpressed Sst, whereas no double-labeled cells were observed in IC. The present results suggest that Sst and Crh cell types are a substantial component of the descending pathways from the amygdala and/or BNST to the PBN and are positioned to exert neuromodulatory effects on central taste processing.
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Affiliation(s)
- Ali Magableh
- Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Robert Lundy
- Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, Louisville, KY 40202, USA
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Weiss MS, Victor JD, Di Lorenzo PM. Taste coding in the parabrachial nucleus of the pons in awake, freely licking rats and comparison with the nucleus of the solitary tract. J Neurophysiol 2013; 111:1655-70. [PMID: 24381029 DOI: 10.1152/jn.00643.2013] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In the rodent, the parabrachial nucleus of the pons (PbN) receives information about taste directly from the nucleus of the solitary tract (NTS). Here we examined how information about taste quality (sweet, sour, salty, and bitter) is conveyed in the PbN of awake, freely licking rats, with a focus on how this information is transformed from the incoming NTS signals. Awake rats with electrodes in the PbN had free access to a lick spout that delivered taste stimuli (5 consecutive licks; 100 mM NaCl, 10 mM citric acid, 0.01 mM quinine HCl, or 100 mM sucrose and water) or water (as a rinse) on a variable-ratio schedule. To assess temporal coding, a family of metrics that quantifies the similarity of two spike trains in terms of spike count and spike timing was used. PbN neurons (n = 49) were generally broadly tuned across taste qualities with variable response latencies. Some PbN neurons were quiescent during lick bouts, and others, some taste responsive, showed time-locked firing to the lick pattern. Compared with NTS neurons, spike timing played a larger role in signaling taste in the first 2 s of the response, contributing significantly in 78% (38/49) of PbN cells compared with 45% of NTS cells. Also, information from temporal coding increased at a faster rate as the response unfolded over time in PbN compared with NTS. Collectively, these data suggest that taste-related information from NTS converges in the PbN to enable a subset of PbN cells to carry a larger information load.
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Affiliation(s)
- Michael S Weiss
- Department of Psychology, Binghamton University, Binghamton, New York; and
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13
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Sugita M, Yamamoto K, Hirono C, Shiba Y. Functional dissection of sweet and bitter taste pathways. J Oral Biosci 2013. [DOI: 10.1016/j.job.2013.02.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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14
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Tokita K, Boughter JD. Sweet-bitter and umami-bitter taste interactions in single parabrachial neurons in C57BL/6J mice. J Neurophysiol 2012; 108:2179-90. [PMID: 22832571 DOI: 10.1152/jn.00465.2012] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We investigated sweet-bitter and umami-bitter mixture taste interactions by presenting sucrose or umami stimuli mixed with quinine hydrochloride (QHCl) while recording single-unit activity of neurons in the parabrachial nucleus (PbN) of urethane-anesthetized C57BL/6J mice. A total of 70 taste-responsive neurons were classified according to which stimulus evoked the greatest net response (36 sucrose-best, 19 NaCl-best, 6 citric acid-best, and 9 QHCl-best). Although no neurons responded best to monopotassium glutamate (MPG) or inosine 5'-monophosphate (IMP), the combination of these two stimuli evoked a synergistic response (i.e., response > 120% of the sum of the component responses) in all sucrose-best and some NaCl-best neurons (n = 43). Adding QHCl to sucrose or MPG + IMP resulted in suppression of the response (responses to mixture < responses to the more effective component) in 41 of 43 synergistic neurons. Neurons showing QHCl suppression were classified into two types: an "MS1" type (n = 27) with suppressed responses both to sucrose and MPG + IMP and an "MS2" type (n = 14) that showed suppressed responses only to sucrose. No neuron displayed suppressed responses to MPG or IMP alone. The suppression ratio (1 - mixture response/sucrose or MPG + IMP response) of sucrose and MPG + IMP in MS1 neurons had a weak positive correlation (r = 0.36). The pattern of reconstructed recording sites of neuron types suggested chemotopic organization in the PbN. Although a peripheral basis for QHCl suppression has been demonstrated, our results suggest that convergence in the PbN plays a role in shaping responses to taste mixtures.
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Affiliation(s)
- Kenichi Tokita
- Dept. of Anatomy and Neurobiology, Univ. of Tennessee Health Science Center, Memphis, TN 38163, USA
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Treesukosol Y, Spector AC. Orosensory detection of sucrose, maltose, and glucose is severely impaired in mice lacking T1R2 or T1R3, but Polycose sensitivity remains relatively normal. Am J Physiol Regul Integr Comp Physiol 2012; 303:R218-35. [PMID: 22621968 DOI: 10.1152/ajpregu.00089.2012] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Evidence in the literature supports the hypothesis that the T1R2+3 heterodimer binds to compounds that humans describe as sweet. Here, we assessed the necessity of the T1R2 and T1R3 subunits in the maintenance of normal taste sensitivity to carbohydrate stimuli. We trained and tested water-restricted T1R2 knockout (KO), T1R3 KO and their wild-type (WT) same-sex littermate controls in a two-response operant procedure to sample a fluid and differentially respond on the basis of whether the stimulus was water or a tastant. Correct responses were reinforced with water and incorrect responses were punished with a time-out. Testing was conducted with a modified descending method of limits procedure across daily 25-min sessions. Both KO groups displayed severely impaired performance and markedly decreased sensitivity when required to discriminate water from sucrose, glucose, or maltose. In contrast, when Polycose was tested, KO mice had normal EC(50) values for their psychometric functions, with some slight, but significant, impairment in performance. Sensitivity to NaCl did not differ between these mice and their WT controls. Our findings support the view that the T1R2+3 heterodimer is the principal receptor that mediates taste detection of natural sweeteners, but not of all carbohydrate stimuli. The combined presence of T1R2 and T1R3 appears unnecessary for the maintenance of relatively normal sensitivity to Polycose, at least in this task. Some detectability of sugars at high concentrations might be mediated by the putative polysaccharide taste receptor, the remaining T1R subunit forming either a homodimer or heteromer with another protein(s), or nontaste orosensory cues.
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Affiliation(s)
- Yada Treesukosol
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, FL 32306, USA
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Tandon S, Simon SA, Nicolelis MAL. Appetitive changes during salt deprivation are paralleled by widespread neuronal adaptations in nucleus accumbens, lateral hypothalamus, and central amygdala. J Neurophysiol 2012; 108:1089-105. [PMID: 22572944 DOI: 10.1152/jn.00236.2012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Salt appetite is a goal-directed behavior in which salt-deprived animals ingest high salt concentrations that they otherwise find aversive. Because forebrain areas such as the lateral hypothalamus (LH), central amygdala (CeA), and nucleus accumbens (NAc) are known to play an important role in this behavior, we recorded from these areas while water-deprived (WD) and salt-deprived (SD) rats performed a two-bottle choice test between 0.5 M salt (NaCl) and 0.4 M sucrose. In the SD state, the preference ratio for high molar salt markedly increased. Electrophysiological recordings analyzed with respect to the onset of licking clusters revealed the presence of both excitatory and inhibitory neuronal responses during salt and/or sucrose consumption. In the NAc, putative medium spiny neurons and tonically active neurons exhibited excitatory and inhibitory responses. In all areas, compared with those recorded during the WD state, neurons recorded during the SD state showed an increase in the percentage of salt-evoked excitatory responses and a decrease in the percentage of sucrose-evoked inhibitory responses, suggesting that a subset of the neuronal population in these areas codes for the increased motivational and/or hedonic value of the salt solution. In addition, in the SD state, the firing of excitatory neurons in LH and CeA became more synchronized, indicating a greater functional connectivity between salt-responsive neurons in these areas. We propose that plastic changes in the feeding-related neuronal populations of these forebrain areas arise when changes in metabolic state alter the hedonic and motivational value of a particular taste stimulus.
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Affiliation(s)
- Shashank Tandon
- Department of Neurobiology, Duke University Medical Center, Durham, NC, USA.
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Ho AS, Hori E, Nguyen PHT, Urakawa S, Kondoh T, Torii K, Ono T, Nishijo H. Hippocampal neuronal responses during signaled licking of gustatory stimuli in different contexts. Hippocampus 2012; 21:502-19. [PMID: 20087892 DOI: 10.1002/hipo.20766] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Neuroanatomical studies suggest that hippocampal formation (HF) receives information from all sensory modalities including taste via the parahippocampal cortices. To date, however, no neurophysiological study has reported that HF neurons encode taste information. In the present study, we recorded CA1 HF neurons from freely behaving rats during performance of a visually-guided licking task in two different triangular chambers. When a cue lamp came on, the rats were required to press a bar to trigger a tube to protrude into the chambers for 3 s. During this period, the rats could lick one of six sapid solutions: [0.1M NaCl (salty), 0.3M sucrose (sweet), 0.01 M citric acid (sour), 0.0001 M quinine HCl (bitter), 0.01 M monosodium L-glutamate (MSG, umami), and a mixture of MSG and 0.001 M disodium-5'-inosinate (IMP) (MSG+IMP)], and distilled water. Of a total 285 pyramidal and interneurons, the activity of 173 was correlated with at least one of the events in the task-illumination of cue lamps, bar pressing, or licking the solution. Of these, 137 neurons responded during licking, and responses of 62 of these cells were greater to sapid solutions than to water (taste neurons). Multivariate analyses of the taste neurons suggested that, in the HF, taste quality might be encoded based on hedonic value. Furthermore, the activity of most taste neurons was chamber-specific. These results implicate the HF in guiding appetitive behaviors such as conditioned place preference.
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Affiliation(s)
- Anh Son Ho
- System Emotional Science, Graduate School of Medicine and Pharmaceutical Science, University of Toyama, Toyama, Japan
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Tokita K, Yamamoto T, Boughter JD. Gustatory neural responses to umami stimuli in the parabrachial nucleus of C57BL/6J mice. J Neurophysiol 2011; 107:1545-55. [PMID: 22170968 DOI: 10.1152/jn.00799.2011] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Umami is considered to be the fifth basic taste quality and is elicited by glutamate. The mouse is an ideal rodent model for the study of this taste quality because of evidence that suggests that this species, like humans, may sense umami-tasting compounds as unique from other basic taste qualities. We performed single-unit recording of taste responses in the parabrachial nucleus (PbN) of anesthetized C57BL/6J mice to investigate the central representation of umami taste. A total of 52 taste-responsive neurons (22 sucrose-best, 19 NaCl-best, 5 citric acid-best, and 6 quinine-best) were recorded from stimulation period with a large panel of basic and umami-tasting stimuli. No neuron responded best to monopotassium glutamate (MPG) or inosine 5'-monophosphate (IMP), suggesting convergence of input in the central nervous system. Synergism induced by an MPG-IMP mixture was observed in all sucrose-best and some NaCl-best neurons that possessed strong sensitivity to sucrose. In more than half of sucrose-best neurons, the MPG-IMP mixture evoked stronger responses than those elicited by their best stimulus. Furthermore, hierarchical cluster analysis and multidimensional analysis indicated close similarity between sucrose and the MPG-IMP mixture. These results strongly suggest the mixture tastes sweet to mice, a conclusion consistent with previous findings that show bidirectional generalization of conditioned taste aversion between sucrose and umami mixtures, and suppression of taste responses to both sucrose and mixtures by the antisweet polypeptide gurmarin in the chorda tympani nerve. The distribution pattern of reconstructed recording sites of specific neuron types suggested chemotopic organization in the PbN.
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Affiliation(s)
- Kenichi Tokita
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA.
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Matsuyama N, Uwano T, Hori E, Ono T, Nishijo H. Reward Contingency Modulates Neuronal Activity in Rat Septal Nuclei during Elemental and Configural Association Tasks. Front Behav Neurosci 2011; 5:26. [PMID: 21633493 PMCID: PMC3100519 DOI: 10.3389/fnbeh.2011.00026] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Accepted: 05/05/2011] [Indexed: 11/18/2022] Open
Abstract
It has been suggested that septal nuclei are important in the control of behavior during various reward and non-reward situations. In the present study, neuronal activity was recorded from rat septal nuclei during discrimination of conditioned sensory stimuli (CSs) of the medial forebrain bundle associated with or without a reward (sucrose solution or intracranial self-stimulation, ICSS). Rats were trained to lick a spout protruding close to the mouth just after a CS to obtain a reward stimulus. The CSs included both elemental and configural stimuli. In the configural condition, the reward contingency of the stimuli presented together was opposite to that of each elemental stimulus presented alone, although the same sensory stimuli were involved. Of the 72 responsive septal neurons, 18 responded selectively to the CSs predicting reward (CS(+)-related), four to the CSs predicting non-reward (CS(0)-related), nine to some CSs predicting reward or non-reward, and 15 non-differentially to all CSs. The remaining 26 neurons responded mainly during the ingestion/ICSS phase. A multivariate analysis of the septal neuronal responses to elemental and configural stimuli indicated that septal neurons encoded the CSs based on reward contingency, regardless of the stimulus physical properties and were categorized into three groups; CSs predicting the sucrose solution, CSs predicting a non-reward, and CSs predicting ICSS. The results suggest that septal nuclei are deeply involved in discriminating the reward contingency of environmental stimuli to manifest appropriate behaviors in response to changing stimuli.
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Affiliation(s)
- Nozomu Matsuyama
- System Emotional Science, Graduate School of Medicine and Pharmaceutical Sciences, University of ToyamaToyama, Japan
- Department of Neurosurgery, Faculty of Medicine, Kagoshima UniversityKagoshima, Japan
| | - Teruko Uwano
- Integrative Neuroscience, Graduate School of Medicine and Pharmaceutical Sciences, University of ToyamaToyama, Japan
| | - Etsuro Hori
- System Emotional Science, Graduate School of Medicine and Pharmaceutical Sciences, University of ToyamaToyama, Japan
| | - Taketoshi Ono
- Judo Neurophysiotherapy, Graduate School of Medicine and Pharmaceutical Sciences, University of ToyamaToyama, Japan
| | - Hisao Nishijo
- System Emotional Science, Graduate School of Medicine and Pharmaceutical Sciences, University of ToyamaToyama, Japan
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Blonde G, Jiang E, Garcea M, Spector AC. Learning-based recovery from perceptual impairment in salt discrimination after permanently altered peripheral gustatory input. Am J Physiol Regul Integr Comp Physiol 2010; 299:R1027-36. [PMID: 20554935 DOI: 10.1152/ajpregu.00843.2009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Rats lacking input to the chorda tympani (CT) nerve, a facial nerve branch innervating anterior tongue taste buds, show robust impairments in salt discrimination demonstrating its necessity. We tested the sufficiency of the CT for salt taste discrimination and whether the remaining input provided by the greater superficial petrosal (GSP) nerve, a facial nerve branch innervating palatal taste buds, or by the glossopharyngeal (GL) nerve, innervating posterior tongue taste buds, could support performance after extended postsurgical testing. Rats presurgically trained and tested in a two-response operant task to discriminate NaCl from KCl were subjected to sham surgery or transection of the CT (CTx), GL (GLx), or GSP (GSPx), alone or in combination. While initially reduced postsurgically, performance by rats with an intact GSP after CTx + GLx increased to normal over 6 wk of testing. Rats with CTx + GSPx consistently performed near chance levels. In contrast, rats with GSPx + GLx were behaviorally normal. A subset of rats subjected to sham surgery and exposed to lower concentrations during postsurgical testing emulating decreased stimulus intensity after neurotomy showed no significant impairment. These results demonstrate that CTx changes the perceptual nature of NaCl and/or KCl, leading to severe initial postsurgical impairments in discriminability, but a "new" discrimination can be relearned based on the input of the GSP. Despite losing ∼75% of their taste buds, rats are unaffected after GSPx + GLx, demonstrating that the CT is not only necessary, but also sufficient, for maintaining salt taste discrimination, notwithstanding the unlikely contribution of the small percentage of taste receptors innervated by the superior laryngeal nerve.
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Affiliation(s)
- Ginger Blonde
- Department of Psychology, Center for Smell and Taste, University of Florida, Gainesville, 32306-4301, USA
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21
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Parabrachial nucleus neuronal responses to off-vertical axis rotation in macaques. Exp Brain Res 2009; 202:271-90. [PMID: 20039027 DOI: 10.1007/s00221-009-2130-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Accepted: 12/07/2009] [Indexed: 10/20/2022]
Abstract
The caudal aspect of the parabrachial nucleus (PBN) contains neurons responsive to whole body, periodic rotational stimulation in alert monkeys (Balaban et al. in J Neurophysiol 88:3175-3193, 2002). This study characterizes the angular and linear motion-sensitive response properties of PBN unit responses during off-vertical axis rotation (OVAR) and position trapezoid stimulation. The OVAR responses displayed a constant firing component which varied from the firing rate at rest. Nearly two-thirds of the units also modulated their discharges with respect to head orientation (re: gravity) during constant velocity OVAR stimulation. The modulated response magnitudes were equal during ipsilateral and contralateral OVARs, indicative of a one-dimensional accelerometer. These response orientations during OVAR divided the units into three spatially tuned populations, with peak modulation responses centered in the ipsilateral ear down, contralateral anterior semicircular canal down, and occiput down orientations. Because the orientation of the OVAR modulation response was opposite in polarity to the orientation of the static tilt component of responses to position trapezoids for the majority of units, the linear acceleration responses were divided into colinear dynamic linear and static tilt components. The orientations of these unit responses formed two distinct population response axes: (1) units with an interaural linear response axis and (2) units with an ipsilateral anterior semicircular canal-contralateral posterior semicircular canal plane linear response axis. The angular rotation sensitivity of these units is in a head-vertical plane that either contains the linear acceleration response axis or is perpendicular to the linear acceleration axis. Hence, these units behave like head-based ('strapdown') inertial guidance sensors. Because the PBN contributes to sensory and interoceptive processing, it is suggested that vestibulo-recipient caudal PBN units may detect potentially dangerous anomalies in control of postural stability during locomotion. In particular, these signals may contribute to the range of affective and emotional responses that include panic associated with falling, malaise associated with motion sickness and mal-de-debarquement, and comorbid balance and anxiety disorders.
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22
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Panguluri S, Saggu S, Lundy R. Comparison of somatostatin and corticotrophin-releasing hormone immunoreactivity in forebrain neurons projecting to taste-responsive and non-responsive regions of the parabrachial nucleus in rat. Brain Res 2009; 1298:57-69. [PMID: 19699720 PMCID: PMC2769563 DOI: 10.1016/j.brainres.2009.08.038] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2009] [Revised: 08/12/2009] [Accepted: 08/13/2009] [Indexed: 02/06/2023]
Abstract
Several forebrain areas have been shown to project to the parabrachial nucleus (PBN) and exert inhibitory and excitatory influences on taste processing. The neurochemicals by which descending forebrain inputs modulate neural taste-evoked responses remain to be established. This study investigated the existence of somatostatin (SS) and corticotrophin-releasing factor (CRF) in forebrain neurons that project to caudal regions of the PBN responsive to chemical stimulation of the anterior tongue as well as more rostral unresponsive regions. Retrograde tracer was iontophoretically or pressure ejected from glass micropipettes, and 7 days later the animals were euthanized for subsequent immunohistochemical processing for co-localization of tracer with SS and CRF in tissue sections containing the lateral hypothalamus (LH), central nucleus of the amygdala (CeA), bed nucleus of the stria terminalis (BNST), and insular cortex (IC). In each forebrain site, robust labeling of cells with distinguishable nuclei and short processes was observed for SS and CRF. The results indicate that CRF neurons in each forebrain site send projections throughout the rostral caudal extent of the PBN with a greater percentage terminating in regions rostral to the anterior tongue-responsive area. For SS, the percentage of double-labeled neurons was more forebrain site specific in that only BNST and CeA exhibited significant numbers of double-labeled neurons. Few retrogradely labeled cells in LH co-expressed SS, while no double-labeled cells were observed in IC. Again, tracer injections into rostral PBN resulted in a greater percentage of double-labeled neurons in BNST and CeA compared to caudal injections. The present results suggest that some sources of descending forebrain input might utilize somatostatin and/or CRF to exert a broad influence on sensory information processing in the PBN.
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Affiliation(s)
- Siva Panguluri
- Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, Louisville, Kentucky 40202
| | - Shalini Saggu
- Department of Pharmaceutical Sciences, Medical University of South Carolina, College of Pharmacy, Charleston, South Carolina 29425
| | - Robert Lundy
- Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, Louisville, Kentucky 40202
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Treesukosol Y, Blonde GD, Spector AC. T1R2 and T1R3 subunits are individually unnecessary for normal affective licking responses to Polycose: implications for saccharide taste receptors in mice. Am J Physiol Regul Integr Comp Physiol 2009; 296:R855-65. [PMID: 19158407 DOI: 10.1152/ajpregu.90869.2008] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The T1R2 and T1R3 proteins are expressed in taste receptor cells and form a heterodimer binding with compounds described as sweet by humans. We examined whether Polycose taste might be mediated through this heterodimer by testing T1R2 knockout (KO) and T1R3 KO mice and their wild-type (WT) littermate controls in a series of brief-access taste tests (25-min sessions with 5-s trials). Sucrose, Na-saccharin, and Polycose were each tested for three consecutive sessions with order of presentation varied among subgroups in a Latin-Square manner. Both KO groups displayed blunted licking responses and initiated significantly fewer trials of sucrose and Na-saccharin across a range of concentrations. KO mice tested after Polycose exposure demonstrated some degree of concentration-dependent licking of sucrose, likely attributable to learning related to prior postingestive experience. These results are consistent with prior findings in the literature, implicating the T1R2+3 heterodimer as the principal taste receptor for sweet-tasting ligands, and also provide support for the potential of postingestive experience to influence responding in the KO mice. In contrast, T1R2 KO and T1R3 KO mice displayed concentration-dependent licking responses to Polycose that tracked those of their WT controls and in some cases licked midrange concentrations more; the number of Polycose trials initiated overall did not differ between KO and WT mice. Thus, the T1R2 and T1R3 proteins are individually unnecessary for normal concentration-dependent licking of Polycose to be expressed in a brief-access test. Whether at least one of these T1R protein subunits is necessary for normal Polycose responsiveness remains untested. Alternatively, there may be a novel taste receptor(s) that mediates polysaccharide taste.
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Affiliation(s)
- Yada Treesukosol
- Dept. of Psychology, Florida State Univ., Tallahassee FL 32306-4301, USA.
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Lundy RF. Gustatory hedonic value: potential function for forebrain control of brainstem taste processing. Neurosci Biobehav Rev 2008; 32:1601-6. [PMID: 18675299 DOI: 10.1016/j.neubiorev.2008.07.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2008] [Revised: 05/29/2008] [Accepted: 07/07/2008] [Indexed: 10/21/2022]
Abstract
Among well-nourished populations, eating beyond homeostatic needs when presented with caloric-dense palatable food evidences the assertion that an increasing proportion of consumption is driven by pleasure, not just by the need for calories. This presents a major health crisis because the affective component of foods constitutes a behavioral risk factor that promotes over consumption [Sorensen, L.B., Moller, P., Flint, A., Martens, M., Raben, A., 2003. Effect of sensory perception of foods on appetite and food intake: a review of studies on humans. Int. J. Obes. Relat. Metab. Disord. 27, 1152-1166; Yeomans, M.R., Blundell, J.E., Leshem, M., 2004. Palatability: response to nutritional need or need-free stimulation of appetite? Br. J. Nutr. 92 (Suppl. 1), S3-S14]. Overweight or obese individuals have an increased risk of developing hypertension, stroke, heart disease, chronic musculoskeletal problems, type-2 diabetes, and certain types of cancers [Hill, J.O., Catenacci, V., Wyatt, H.R., 2005. Obesity: overview of an epidemic. Psychiatr. Clin. N. Am. 28, 1-23, vii]. The etiology of obesity is complex involving genetic, metabolic, and behavioral factors, but ultimately results from long-term energy imbalance. Evidence indicates that learned and some forms of unlearned control of ingestive behavior driven by palatability (i.e. hedonic value) are critically dependent on reciprocal interactions between brainstem gustatory nuclei and the ventral forebrain. This review discusses the current understanding of centrifugal control of taste processing in subcortical gustatory nuclei and the potential role of such modulation in hedonic responding.
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Affiliation(s)
- Robert F Lundy
- University of Louisville School of Medicine, Department of Anatomical Sciences and Neurobiology, 500 South Preston Street, Louisville, KY 40292, United States.
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Bonacchi KB, Ackroff K, Sclafani A. Sucrose taste but not Polycose taste conditions flavor preferences in rats. Physiol Behav 2008; 95:235-44. [PMID: 18602411 DOI: 10.1016/j.physbeh.2008.06.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2008] [Revised: 05/28/2008] [Accepted: 06/10/2008] [Indexed: 10/21/2022]
Abstract
Rats have an inborn preference for sweet taste and learn to prefer flavors associated with sweetness. They are also strongly attracted to the taste of glucose polymers (e.g., Polycose). This "poly" taste differs in quality from the sweet taste of sugar. To determine if poly taste, like sweet taste, conditions flavor preferences rats were trained with a distinctive flavor (CS+) added to 2% Polycose solution and a different flavor (CS-) added to plain water. In a subsequent two-bottle test the rats did not prefer the CS+ to CS- when both flavors were presented in water. In contrast, other rats significantly preferred a CS+ flavor that had been paired with 2% sucrose. Adding saccharin to a flavored Polycose solution did not improve CS+ flavor learning; rather, Polycose appeared to overshadow saccharin-induced conditioning. Flavor conditioning by a 16% Polycose solution was assessed using a sham-feeding procedure to prevent post-oral reinforcement. Although the rats sham-fed substantial amounts of the CS+ flavored Polycose solution, they failed to prefer the CS+ to the CS- flavor. This contrasts with the preference other rats displayed for a CS+ paired with sham-fed sucrose. Why attractive sweet and poly tastes differ in their ability to condition flavor preferences is not certain, although some findings suggest that they differentially activate dopamine and/or serotonin circuits involved in flavor learning.
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Natural stimuli evoke dynamic sequences of states in sensory cortical ensembles. Proc Natl Acad Sci U S A 2007; 104:18772-7. [PMID: 18000059 DOI: 10.1073/pnas.0705546104] [Citation(s) in RCA: 191] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Although temporal coding is a frequent topic of neurophysiology research, trial-to-trial variability in temporal codes is typically dismissed as noise and thought to play no role in sensory function. Here, we show that much of this supposed "noise" faithfully reflects stimulus-related processes carried out in coherent neural networks. Cortical neurons responded to sensory stimuli by progressing through sequences of states, identifiable only in examinations of simultaneously recorded ensembles. The specific times at which ensembles transitioned from state to state varied from trial to trial, but the state sequences were reliable and stimulus-specific. Thus, the characterization of ensemble responses in terms of state sequences captured facets of sensory processing that are missing from, and obscured in, other analyses. This work provides evidence that sensory neurons act as parts of a systems-level dynamic process, the nature of which can best be appreciated through observation of distributed ensembles.
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Abstract
Sensory processing is modulated by attention, which is a function of network states. Here we show that changes in such states do more than a simple gating of stimuli: they actually re-arrange cortical coding space to emphasize emotional valences. We delivered taste stimuli to rats before and after a spontaneous state change ("disengagement") that is associated with a reduction in attention and a concurrent emergence of cortical mu rhythms. The percentage of cortical neurons that responded to tastes, and the average response across neurons, remained stable with disengagement, but the particulars of the responses changed drastically. The distinctiveness of sucrose and quinine-which represent the high and low ends of the palatability spectrum-increased, the distinctiveness of the two aversive tastes (quinine and citric acid) decreased, and the distinctiveness of sucrose and NaCl, which were almost identically palatable to start with, did not change. Overall, then, the changes appeared to be palatability-specific. Two additional findings were consistent with this conclusion: rats' palatability-related behavioral responses to the tastes changed in similar ways with disengagement and disengagement-related neural changes specifically appeared late in the response, when palatability-specific information emerges in cortical responses. These data suggest that neural state changes can change the content of neural codes.
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Affiliation(s)
- Alfredo Fontanini
- Volen National Center for Complex Systems, MS 013, Brandeis University, 415 South Street, Waltham, MA 02454, USA.
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28
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Spector AC, Travers SP. The representation of taste quality in the mammalian nervous system. ACTA ACUST UNITED AC 2006; 4:143-91. [PMID: 16510892 DOI: 10.1177/1534582305280031] [Citation(s) in RCA: 137] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The process by which the mammalian nervous system represents the features of a sapid stimulus that lead to a perception of taste quality has long been controversial. The labeled-line (sparse coding) view differs from the across-neuron pattern (ensemble) counterpoint in proposing that activity in a given class of neurons is necessary and sufficient to generate a specific taste perception. This article critically reviews molecular, electro-physiological, and behavioral findings that bear on the issue. In the peripheral gustatory system, the authors conclude that most qualities appear to be signaled by labeled lines; however, elements of both types of coding characterize signaling of sodium salts. Given the heterogeneity of neuronal tuning functions in the brain, the central coding mechanism is less clear. Both sparse coding and neuronal ensemble models remain viable possibilities. Furthermore, temporal patterns of discharge could contribute additional information. Ultimately, until specific classes of neurons can be selectively manipulated and perceptual consequences assessed, it will be difficult to go beyond mere correlation and conclusively discern the validity of these coding models.
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Affiliation(s)
- Alan C Spector
- Department of Psychology and Center for Smell and Taste, University of Florida
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29
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Walker CD. Nutritional aspects modulating brain development and the responses to stress in early neonatal life. Prog Neuropsychopharmacol Biol Psychiatry 2005; 29:1249-63. [PMID: 16253410 DOI: 10.1016/j.pnpbp.2005.08.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/26/2005] [Indexed: 10/25/2022]
Abstract
Nutrition is one of the critical factors insuring adequate growth and development in all species. In particular, brain development is sensitive to specific nutrient intake such as proteins and lipids, which are important for cell membrane formation and myelinization. Carbohydrate intake insures adequate short-term energy supply, but has important effects on the activity of the hypothalamic-pituitary-adrenal (HPA) axis to regulate stress responsiveness. This review focuses on the effects of carbohydrates and fat on the activity of the HPA axis as well as other brain-related functions such as pain modulation, neuropeptide and neurotransmitters release, and some aspects related to cognitive functions. The role of leptin, DHA and AA as mediators of the effects of fat on the brain is discussed.
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Affiliation(s)
- Claire-Dominique Walker
- Douglas Hospital Research Center, Department of Psychiatry, McGill University, Montreal, 6875 Lasalle Blvd, Verdun, QC, Canada H4H 1R3.
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Furusawa AA, Hori E, Umeno K, Tabuchi E, Ono T, Nishijo H. Unambiguous representation of overlapping serial events in the rat hippocampal formation. Neuroscience 2005; 137:685-98. [PMID: 16297564 DOI: 10.1016/j.neuroscience.2005.09.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2005] [Revised: 09/03/2005] [Accepted: 09/06/2005] [Indexed: 11/22/2022]
Abstract
The hippocampal formation is suggested to be crucial in unambiguous representation of overlapping temporal sequences in episodic memory. We hypothesized that, if this was true, the hippocampal formation neurons would differentially respond to the same elements even in different temporal sequences. The present study was designed to investigate hippocampal formation CA1 neuronal activity of rats during performance of a conditional delayed stimulus-response association task in which three stimuli were conditionally and serially presented with a delay. In the task, the pairs of the second and third stimuli were overlapped across the trials, but separated by the preceding first stimuli. Conditioned tones coming from one of three possible directions were followed, after a short delay, by one of three pairs of reinforcement series. The pairs consisted of air puff (aversive sensory stimuli) and tube protrusion (which allowed licking sucrose behavior) in the following combinations: air puff-tube protrusion, tube protrusion-tube protrusion and tube protrusion-air puff. The pairs were interposed by a 2 s delay. The three conditioned tone directions were associated with these three pairs in a one-to-one correspondence, and its association was conditional to three possible conditioned tone frequencies (300, 530, and 1,200 Hz). The responses of 107 neurons to the air puff and tube protrusion were analyzed by two-way ANOVA (task condition x reinforcement situation). Of 42 air puff-responsive and 64 tube protrusion-responsive neurons, 36 and 53 displayed significant main effects and/or significant interaction, respectively. Furthermore, neural responses during the delay periods were dependent on the task conditions. The results indicated that the majority of the hippocampal formation neurons showed task condition- and/or reinforcement situation-dependent responses, suggesting a crucial role of the hippocampal formation in representation of overlapping serial events in episodic memory.
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Affiliation(s)
- A A Furusawa
- System Emotional Science, Graduate School of Medicine, University of Toyama, Sugitani 2630, Toyama 930-0194, Japan
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31
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Smith DV, Ye MK, Li CS. Medullary taste responses are modulated by the bed nucleus of the stria terminalis. Chem Senses 2005; 30:421-34. [PMID: 15872146 DOI: 10.1093/chemse/bji037] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Previous studies have shown a modulatory influence of limbic forebrain areas, such as the central nucleus of the amygdala and lateral hypothalamus, on the activity of taste-responsive cells in the nucleus of the solitary tract (NST). The bed nucleus of the stria terminalis (BST), which receives gustatory afferent information, also sends descending axons to the NST. The present studies were designed to investigate the role of the BST in the modulation of NST gustatory activity. Extracellular action potentials were recorded from 101 taste-responsive cells in the NST of urethane-anesthetized hamsters and analyzed for a change in excitability following bilateral electrical stimulation of the BST. The response of NST taste cells to stimulation of the BST was predominately inhibitory. Orthodromic inhibitory responses were observed in 29 of 101 (28.7%) NST taste-responsive cells, with four cells inhibited bilaterally. An increase in excitability was observed in seven of the 101 (6.9%) NST taste cells. Of the 34 cells showing these responses, 25 were modulated by the ipsilateral BST and 15 by the contralateral; four were inhibited bilaterally and two inhibited ipsilaterally and excited contralaterally. The duration of inhibitory responses (mean = 177.9 ms) was significantly longer than that of excitatory responses (35.4 ms). Application of subthreshold electrical stimulation to the BST during taste trials inhibited or excited the taste responses of every BST-responsive NST cell tested with this protocol. NST neurons that were most responsive to sucrose, NaCl, citric acid or quinine hydrochloride were all affected by BST stimulation, although citric acid-best cells were significantly more often modulated and NaCl-best less often modulated than expected by chance. These results combine with excitatory and inhibitory modulation of NST neurons by the insular cortex, lateral hypothalamus and central nucleus of the amygdala to demonstrate extensive centrifugal modulation of brainstem gustatory neurons.
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Affiliation(s)
- David V Smith
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, 855 Monroe Avenue, Suite 515, Memphis, TN 38163, USA.
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32
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St John SJ, Hallagan LD. Psychophysical investigations of cetylpyridinium chloride in rats: its inherent taste and modifying effects on salt taste. Behav Neurosci 2005; 119:265-79. [PMID: 15727531 DOI: 10.1037/0735-7044.119.1.265] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Salts are transduced by at least 2 mechanisms: (a) antagonized by amiloride and (b) antagonized by cetylpyridinium chloride (CPC). The authors report on 4 behavioral experiments in rats that characterize the orosensory properties of CPC itself as well as its effect in suppressing the intensity of NaCl and KCl taste. Experiments 1 and 2 indicated that CPC has a quinine-like taste quality. Experiments 3 and 4 demonstrated that the recognition of KCl, but not NaCl, is modestly reduced by mixture with CPC. However, control experiments call into question the mechanism of the salt suppression of CPC, because both CPC-salt and quinine-salt mixtures had similar effects. The relevance of these studies for understanding salt and bitter taste coding is discussed.
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Affiliation(s)
- Steven J St John
- Department of Psychology, Reed College, Portland, OR 97202, USA.
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Kang Y, Yan J, Huang T. Microinjection of bicuculline into the central nucleus of the amygdala alters gustatory responses of the rat parabrachial nucleus. Brain Res 2005; 1028:39-47. [PMID: 15518640 DOI: 10.1016/j.brainres.2004.08.068] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/29/2004] [Indexed: 11/25/2022]
Abstract
The central amygdaloid nucleus (CeA) receives projection from the parabrachial nucleus (PBN) gustatory neurons and descendingly projects to the PBN, and taste responses in the PBN are significantly affected by stimulation or lesion of the CeA. To examine whether the GABA receptors within the CeA are involved in this modulation, the effects of microinjection of bicuculline, a GABA(A)-selective antagonist, into the CeA on the activities of PBN taste neurons were observed by using extracellular recording technique. In general, after bicuculline was administered to ipsilateral CeA, the responses of PBN neurons to four tastants all increased, with the magnitudes significantly higher than those obtained before drug administration (P<0.01), respectively. However, after bicuculline was delivered into the contralateral CeA, only the responses to NaCl, HCl and QHCl increased. According to the best-stimulus category, 47% NaCl-best (8/17), 64% HCl-best (7/11), 80% QHCl-best (4/5), and 33% sucrose-best (1/3) increased their responses to at least one basic taste stimulus after GABA(A) receptors within the ipsilateral CeA were blocked. After contralteral CeA injection, more NaCl-best neurons (6/8) increased responses than that after ipsilateral CeA injection, but other best-stimulus units showed no differences before and after drug injection into the contralateral CeA. Analyses of across-unit patterns indicated that the correlation coefficient of responses between NaCl and sucrose was apparently higher after drug administration to the CeA. However, after drug injection into the contralateral CeA, the correlations between NaCl and the other three tastants were higher than those before. These results indicate that the GABA(A) receptors within the CeA play an important role in modulating the gustatory activities of PBN neurons.
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Affiliation(s)
- Yi Kang
- Department of Physiology, School of Medicine, Xi'an Jiaotong University, 245 Zhuque Street, Xi'an, Shaanxi 710061, People's Republic of China
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34
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Leshem M, del Canho S. Ontogeny of urine preference and its relationship to NH4Cl preference and sodium hunger in suckling rat pups. Dev Psychobiol 2005; 46:111-7. [PMID: 15732056 DOI: 10.1002/dev.20043] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We chart the postnatal ontogeny of urine preference in the suckling rat. Twelve-day-old sucklings, when offered urine, NH4Cl, or NaCl, ingest more urine and NH4Cl than NaCl. When rendered sodium hungry by ivc renin or by sodium depletion, these sucklings prefer urine and NH4Cl to NaCl, dilute urine, or an NaCl and KCl mineral mix equimolar to urine; however, by 18 days of age, urine and NH4Cl are no longer preferred to NaCl. Hence, urine preference in the suckling may be specific and preparatory for the variety of purposes urine preference serves in the adult rat, and it might guide the pup to urinary sodium in the nest. Since preference for urine and NH4Cl covary during postnatal development, the high preference for NH4Cl in midterm sucklings might be because its ammonium flavor is similar to urine.
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Affiliation(s)
- Micah Leshem
- Psychology Department, University of Haifa, Haifa 31905, Israel.
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35
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Abstract
A family of approximately 30 TAS2R bitter taste receptors has been identified in mammals. Their genes evolved through adaptive diversification and are linked to chromosomal loci known to influence bitter taste in mice and humans. The agonists for various TAS2Rs have been identified and all of them were established as bitter tastants. TAS2Rs are broadly tuned to detect multiple bitter substances, explaining, in part, how mammals can recognize numerous bitter compounds with a limited set of receptors. The TAS2Rs are expressed in a subset of taste receptor cells, which are distinct from those mediating responses to other taste qualities. However, cells devoted to the detection of sweet, umami, and bitter stimuli share common signal transduction components. Transgenic expression of a human TAS2R in sweet or bitter taste receptor-expressing cells of mice induced either strong attraction or aversion to the receptor's cognate bitter tastant. Thus, dedicated taste receptor cells appear to function as broadly tuned detectors for bitter substances and are wired to elicit aversive behavior.
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Affiliation(s)
- Wolfgang Meyerhof
- German Institute of Human Nutrition Potsdam-Rehbrücke, Department of Molecular Genetics, Arthur-Scheunert-Allee 114-1 16, 14558 Nuthetal, Germany.
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36
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Tokita K, Karádi Z, Shimura T, Yamamoto T. Centrifugal inputs modulate taste aversion learning associated parabrachial neuronal activities. J Neurophysiol 2004; 92:265-79. [PMID: 14973323 DOI: 10.1152/jn.01090.2003] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Our previous studies have demonstrated that gustatory neurons in the parabrachial nucleus (PBN) show altered responses after the acquisition of conditioned taste aversion (CTA) to NaCl. The present study was conducted 1) to examine centrifugal influences on the altered gustatory activity of CTA-trained rats, and 2) to evaluate the role of amiloride-sensitive (ASN) and -insensitive NaCl (AIN) best units in coding the taste of NaCl. Animals were separated into 2 groups: a CTA group that had acquired taste aversion to 0.1 M NaCl and a control group that underwent pseudoconditioning before the recording experiment. Single-neuron activity, in 2 separate series of experiments, was extracellularly recorded in anesthetized rats. In the stimulation studies, the effects of electrical stimulation of the gustatory cortex (GC) or the central nucleus of amygdala (CeA) were examined on firing of PBN taste units. CeA stimulation produced excitatory effect in significantly more neurons in the CTA group (n = 8) than in the control group (n = 1). Furthermore, ASN-best units in the CTA group showed larger responses to NaCl than similar units in the control group. In the decerebration experiment, there was no statistical difference among the taste responses between the 2 groups in any best-stimulus category. These results suggest that CTA conditioning uses an effective central amygdaloid input to modulate activity of gustatory neurons in the PBN. Data also substantiate that amiloride-sensitive components of NaCl-best neurons play a critical role in the recognition of distinctive taste of NaCl.
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Affiliation(s)
- Ken'ichi Tokita
- Department of Behavioral Physiology, Graduate School of Human Sciences, Osaka University, 1-2 Yamadaoka, Suita, Osaka 565-0871, Japan
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37
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Topolovec JC, Gati JS, Menon RS, Shoemaker JK, Cechetto DF. Human cardiovascular and gustatory brainstem sites observed by functional magnetic resonance imaging. J Comp Neurol 2004; 471:446-61. [PMID: 15022263 DOI: 10.1002/cne.20033] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The reflex control and relay to higher brain sites of visceral sensory information within the central nervous system is mediated via discrete sites in the brainstem. Anatomical characterization of these sites in humans has been limited due to the invasive nature of such research. The present study employed 4 Tesla functional magnetic resonance imaging (fMRI) to characterize brainstem sites involved in autonomic control in the human. Eight subjects performed tasks that activate the general visceral (the isometric hand-grip, maximal inspiration, Valsalva maneuver) or special visceral sensory systems (sucrose administration to the tongue). Activation of the nucleus of the solitary tract and parabrachial nucleus was consistently observed with all general visceral tasks. Periaqueductal gray area activation was observed during the maximal inspiration and Valsalva maneuver conditions and raphe activation was present in response to isometric hand-grip and maximal inspiration tasks. The activation in the nucleus of the solitary tract was consistently more rostral in the medulla during sucrose administration than during performance of the other experimental tasks. This finding is consistent with what has been previously demonstrated in animals. This is the first study to image the human brainstem with respect to visceral control and demonstrates the feasibility of using high-resolution fMRI to study the functional organization of the human brainstem.
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Affiliation(s)
- Jane C Topolovec
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario N6A 5C1, Canada
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38
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Galvin KE, King CT, King MS. Stimulation of Specific Regions of the Parabrachial Nucleus Elicits Ingestive Oromotor Behaviors in Conscious Rats. Behav Neurosci 2004; 118:163-72. [PMID: 14979793 DOI: 10.1037/0735-7044.118.1.163] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The "waist" area and external subnuclei of the parabrachial nucleus (PBN) have been implicated in the processing of gustatory information, yet their behavioral roles are not clearly defined. In the current study, areas within and surrounding the PBN were stimulated while oromotor behaviors were monitored in conscious rats. Electrical and chemical (100 mM glutamate) stimulation of the waist area increased ingestive oromotor behaviors over baseline (p<.01). Stimulation of external PBN subnuclei and areas medial and ventral to the PBN failed to cause a behavioral change. These data support the hypothesis that the waist area of the PBN constitutes part of the neural substrate involved in eliciting oromotor behaviors in response to taste input.
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39
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Lundy RF, Norgren R. Activity in the hypothalamus, amygdala, and cortex generates bilateral and convergent modulation of pontine gustatory neurons. J Neurophysiol 2003; 91:1143-57. [PMID: 14627662 DOI: 10.1152/jn.00840.2003] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Evidence suggests that centrifugal modulation of brain stem gustatory cells might play a role in the elaboration of complex taste-guided behaviors like conditioned taste aversion and sodium appetite. We previously showed that activity in one forebrain area, the central nucleus of the amygdala (CeA), increased the chemical selectivity of taste cells in the parabrachial nucleus (PBN). The present study investigates how activity in 2 other similarly interconnected forebrain sites, the lateral hypothalamus (LH) and gustatory cortex (GC), might influence PBN gustatory processing in rats. The potential convergence of descending inputs from these sites, as well as the CeA, was also evaluated. After anesthesia (35 mg/kg Nembutal ip), 70 PBN gustatory neurons were tested before, during, and after electrical stimulation of these forebrain sites, while responding to 0.3 M sucrose, 0.1 M NaCl, 0.01 M citric acid, and 0.003 M QHCl. Although each forebrain site modulated taste-evoked responses, more PBN neurons were influenced by stimulation of the GC (67%) and CeA (73%) than of the LH (48%). Activation of cortex (71%) and amygdala (85%) most often produced inhibition, whereas inhibition and excitation occurred equally often during hypothalamic stimulation. Of the neurons tested for convergence (n = 60), 88% were influenced by > or =1 of the 3 sites. Twenty were modulated by stimulation at all 3 sites and another 17 by 2 of the 3 sites. The net effect of centrifugal modulation was to sharpen the across-stimulus response profiles of PBN cells, particular with regard to the NaCl- and citric acid-best cells.
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Affiliation(s)
- Robert F Lundy
- Penn State College of Medicine, Department of Neural and Behavioral Sciences, Hershey, Pennsylvania 17033, USA.
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40
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Verhagen JV, Giza BK, Scott TR. Responses to taste stimulation in the ventroposteromedial nucleus of the thalamus in rats. J Neurophysiol 2003; 89:265-75. [PMID: 12522178 DOI: 10.1152/jn.00870.2001] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Extracellular action potentials were recorded from 73 neurons in the parvicellular division of the ventroposteromedial (VPMpc) nucleus of the thalamus of anesthetized Wistar rats during gustatory, thermal, and tactile stimulation of the whole oral cavity. The stimulus array consisted of 16 room-temperature (23 degrees C) sapid stimuli, distilled water at three temperatures (0, 23, and 37 degrees C), and 0.1 M NaCl at three temperatures (0, 23, and 37 degrees C). Among all 151 neurons isolated in VPMpc, 9% responded exclusively to taste, 33% to taste and temperature, none to taste and touch, but 6% to all three modalities. Discharge rates evoked by the basic tastants were 13.8 +/- 1.6 (SD) spikes/s for 0.1 M NaCl, 9.3 +/- 1.4 spikes/s for 0.01 M HCl, 5.1 +/- 0.9 spikes/s for 0.5 M sucrose, and 4.3 +/- 0.6 spikes/s for 0.01 M quinine HCl. Water evoked mean responses at 0, 23, and 37 degrees C of 9.9 +/- 1.5, 0.6 +/- 0.4, and 1.3 +/- 0.9 spikes/s, respectively. The mean firing rate evoked by 37 and 0 degrees C NaCl was 15.0 +/- 2.4 and 17.0 +/- 2.8 spikes/s, respectively. The exponent of the NaCl concentration-response power function was 0.39. Thalamic taste cells were broadly tuned. The mean breadth-of-tuning coefficient for these 73 gustatory cells was 0.79 +/- 0.02. Two cells responded predominantly with inhibition, which accounted for the majority of inhibitory responses. The taste neurons were statistically divisible into three groups: sodium-oriented (n = 40), acid-oriented (n = 12), and sugar-oriented (n = 17). Four additional bitter-oriented neurons were not closely enough related to be defined as a group and were considered outliers. The sodium-oriented group could be divided into three statistically distinct subgroups, differing in the specificity of their responses to NaCl. With respect to polymodal sensitivity, spontaneous rate, evoked response rates, signal-to-noise ratio, proportions of cells responding best to basic tastants, taste neuron groups, taste spaces, and temporal responses, VPMpc neurons have characteristics that are intermediate between those of parabrachial and cortical gustatory neurons.
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41
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Balaban CD, McGee DM, Zhou J, Scudder CA. Responses of primate caudal parabrachial nucleus and Kölliker-fuse nucleus neurons to whole body rotation. J Neurophysiol 2002; 88:3175-93. [PMID: 12466439 DOI: 10.1152/jn.00499.2002] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The caudal aspect of the parabrachial (PBN) and Kölliker-Fuse (KF) nuclei receive vestibular nuclear and visceral afferent information and are connected reciprocally with the spinal cord, hypothalamus, amygdala, and limbic cortex. Hence, they may be important sites of vestibulo-visceral integration, particularly for the development of affective responses to gravitoinertial challenges. Extracellular recordings were made from caudal PBN cells in three alert, adult female Macaca nemestrina through an implanted chamber. Sinusoidal and position trapezoid angular whole body rotation was delivered in yaw, roll, pitch, and vertical semicircular canal planes. Sites were confirmed histologically. Units that responded during rotation were located in lateral and medial PBN and KF caudal to the trochlear nerve at sites that were confirmed anatomically to receive superior vestibular nucleus afferents. Responses to whole-body angular rotation were modeled as a sum of three signals: angular velocity, a leaky integration of angular velocity, and vertical position. All neurons displayed angular velocity and integrated angular velocity sensitivity, but only 60% of the neurons were position-sensitive. These responses to vertical rotation could display symmetric, asymmetric, or fully rectified cosinusoidal spatial tuning about a best orientation in different cells. The spatial properties of velocity and integrated velocity and position responses were independent for all position-sensitive neurons; the angular velocity and integrated angular velocity signals showed independent spatial tuning in the position-insensitive neurons. Individual units showed one of three different orientations of their excitatory axis of velocity rotation sensitivity: vertical-plane-only responses, positive elevation responses (vertical plane plus ipsilateral yaw), and negative elevation axis responses (vertical plane plus negative yaw). The interactions between the velocity and integrated velocity components also produced variations in the temporal pattern of responses as a function of rotation direction. These findings are consistent with the hypothesis that a vestibulorecipient region of the PBN and KF integrates signals from the vestibular nuclei and relay information about changes in whole-body orientation to pathways that produce homeostatic and affective responses.
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Affiliation(s)
- Carey D Balaban
- Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA.
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42
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Geran LC, Garcea M, Spector AC. Transecting the gustatory branches of the facial nerve impairs NH(4)Cl vs. KCl discrimination in rats. Am J Physiol Regul Integr Comp Physiol 2002; 283:R739-47. [PMID: 12185009 DOI: 10.1152/ajpregu.00103.2002] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ammonium and potassium chloride share a common taste quality and an amiloride-insensitive route of transduction. An amiloride-sensitive pathway might also be partially activated by these salts, although very few studies have reported effects of amiloride on nonsodium salt perception. This experiment was designed to determine 1) whether rats could discriminate KCl from NH(4)Cl and, if discrimination was evident, whether performance was impaired with 2) amiloride or 3) gustatory nerve transection. Rats were trained to discriminate KCl from NH(4)Cl (n = 8) and NaCl from NH(4)Cl (n = 8). Amiloride (100 microM) impaired NaCl vs. NH(4)Cl but not KCl vs. NH(4)Cl performance, whereas both groups showed significant impairments after transection of the chorda tympani (CT) and greater superficial petrosal (GSP) branches of the facial nerve. This suggests that rats can discriminate between KCl and NH(4)Cl and that this discrimination does not rely on an amiloride-sensitive mechanism but does depend on the CT and/or GSP nerves. This experiment supports the hypothesis that the facial nerve is important for salt taste recognition and discrimination.
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Affiliation(s)
- Laura C Geran
- Department of Psychology and Center for Smell and Taste, University of Florida, Gainesville, Florida 32611-2250, USA
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43
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Abstract
Cuff electrodes with headcap connectors were implanted around the rat chorda tympani nerve. Whole nerve recordings under anesthesia were made from these nerves every week to chemical, thermal and tactile stimuli applied to the anterior tongue. The signal/noise ratio of these recordings was similar to acute recordings from the chorda tympani nerve, and the nerves were spontaneously active. Responses to chemical as well as thermal and mechanical stimulation of the tongue were recorded as early as 2 and 3 weeks after implantation and recordings from the same nerve were made for more than 3 months. These results have demonstrated the feasibility of making long-term chronic recordings of chemosensory activity in the chorda tympani nerve. The cuff electrode has great potential to provide correlative information between neurophysiological and behavioral data.
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Affiliation(s)
- Yuichi Shimatani
- Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, MI 48109-1078, USA
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44
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Toyomitsu Y, Nishijo H, Uwano T, Kuratsu J, Ono T. Neuronal responses of the rat amygdala during extinction and reassociation learning in elementary and configural associative tasks. Eur J Neurosci 2002; 15:753-68. [PMID: 11886454 DOI: 10.1046/j.1460-9568.2002.01889.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
To investigate functional heterogeneity within the amygdala in appetitive conditioned instrumental behaviours, neuronal activity was recorded from the amygdala of behaving rats during learning and discrimination of conditioned sensory stimuli associated with or without reinforcement [sucrose solution, intracranial self-stimulation (ICSS)]. Sensory stimuli included auditory (tone), visual (light) and configural (simultaneous presentation of tone and light) stimuli. The rat was trained to lick a spout protruded close to its mouth just after a conditioned sensory stimulus to obtain a reward. Of the 609 neurons recorded from the amygdala and amygdalostriatal transition area, 154 responded to one or more sensory stimuli. The 62 amygdalar neurons responded strongly to certain conditioned sensory stimuli associated with rewards. Of these 62 neurons, 45 were tested with the extinction trials. Responses of 31 neurons to conditioned stimuli were finally extinguished, and those of the remaining 14 were not extinguished. Furthermore, responses of 26 of these 31 neurons resumed in the relearning trials (plastic neurons), suggesting that these sensory responses were associative rather than just responses to physical properties of the stimuli. These plastic neurons were located mainly in the basolateral nucleus of the amygdala, and responses of the plastic neurons were correlated with behavioural responses. These results suggest that the basolateral nucleus is crucial in associative learning between sensory information and affective significance for behavioural outputs in appetitive conditioned instrumental behaviours.
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Affiliation(s)
- Yuji Toyomitsu
- Department of Physiology, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Sugitani 2630, Toyama 930-0194, Japan
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45
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Baird JP, Travers JB, Travers SP. Parametric analysis of gastric distension responses in the parabrachial nucleus. Am J Physiol Regul Integr Comp Physiol 2001; 281:R1568-80. [PMID: 11641130 DOI: 10.1152/ajpregu.2001.281.5.r1568] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The parabrachial nucleus (PBN) is regarded as an important locus for the processing and integration of sensory inputs from oral, gastrointestinal, and postabsorptive receptor sites and is thus thought to play an important role in regulating food intake. Gastric distension is an important satiation cue; however, such responses have been qualitatively characterized only over a limited area of the PBN. To more fully characterize gastric distension responses throughout the PBN, the responses of single units to gastric distension were tested using computer-controlled balloon inflation (3-18 ml air) in pentobarbital sodium- and/or urethan-anesthetized male rats. Distension-responsive neurons were indeed distributed throughout the nucleus from rostral areas typically considered to be visceral to more caudal areas associated with gustatory function, providing further anatomical support for the hypothesis that the PBN integrates taste and visceral signals that control feeding. Most PBN neurons had thresholds of 6 ml or less, similar to vagal afferent fibers. However, in contrast to the periphery, there were both excitatory and inhibitory responses. Increases in volume were associated with two distinct effects. First, as volume increased, the response rate increased; second, the duration of the response increased. In fact, in a subset of cells, responses to gastric distension lasted well beyond the stimulation period, particularly at larger volumes. Prolonged gastric distension responses are not common in the periphery and may constitute a central mechanism that contributes to satiation processes.
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Affiliation(s)
- J P Baird
- Oral Biology, College of Dentistry, Ohio State University, Columbus, Ohio 43210, USA.
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46
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Baird JP, Travers SP, Travers JB. Integration of gastric distension and gustatory responses in the parabrachial nucleus. Am J Physiol Regul Integr Comp Physiol 2001; 281:R1581-93. [PMID: 11641131 DOI: 10.1152/ajpregu.2001.281.5.r1581] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Palatable gustatory stimuli promote feeding, whereas gastric distension generally inhibits this behavior. We explored a neural basis for integration of these opposing sensory signals by evaluating the effect of gastric distension on gustatory responses in the parabrachial nucleus (PBN) of anesthetized rats. Sixteen percent of 92 taste cells were coactivated; they responded to independent taste or gastric distension stimulus application. Modulation of taste responses by distension was more prevalent; taste responses declined 37% in response to distension in 25% of the cells and increased by 46% in 10% of cells. Across the whole population, however, the suppressive effect of distension on taste responses was small (6%). The incidence of modulation did not vary as a simple hedonic function of gustatory sensitivity, i.e., similar proportions of sucrose-, citric-acid-, and QHCl-best, but not NaCl-best, neurons were modulated by gastric distension. Coactivated, modulated, and nonmodulated gustatory-responsive cells were intermingled in the gustatory zone of the caudal PBN. The suppression of PBN taste responses by visceral stimulation may reflect a mechanism for satiation and further implicates the PBN in the control of ingestive function.
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Affiliation(s)
- J P Baird
- Oral Biology, College of Dentistry, Ohio State University, Columbus, Ohio 43210, USA.
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Drew JE, Barrett P, Mercer JG, Moar KM, Canet E, Delagrange P, Morgan PJ. Localization of the melatonin-related receptor in the rodent brain and peripheral tissues. J Neuroendocrinol 2001; 13:453-8. [PMID: 11328456 DOI: 10.1046/j.1365-2826.2001.00651.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Previous studies have provided a limited examination of the expression of the orphan melatonin-related receptor in the pituitary and hypothalamus of human and sheep and retinal tissue in the sheep. The present study reports evidence of conservation of expression in regions of the hypothalamus (dorsal medial hypothalamus, lateral hypothalamus, arcuate nucleus), the epithelial layer lining the third ventricle and the paraventricular thalamic nucleus of the mouse, rat and hamster. An extensive and detailed analysis of melatonin-related receptor mRNA expression in the mouse central nervous system and peripheral tissues is presented. Mapping the distribution throughout the entire mouse brain has revealed new sites of expression in a number of brain nuclei, including preoptic areas, parabrachial nuclei and widespread distribution in the olfactory bulb. Reverse transcriptase-polymerase chain reaction was performed with RNA isolated from peripheral tissues revealing expression of the melatonin-related receptor mRNA in the mouse kidney, adrenal gland, intestine, stomach, heart, lung, skin, testis and ovary. These results suggest a conserved function in neuroendocrine regulation and a potential role in coordinating physiological responses in the central nervous system and peripheral tissues.
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Affiliation(s)
- J E Drew
- Molecular Neuroendocrinology Group, Rowett Research Institute, Bucksburn, Aberdeen, UK.
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Bell ME, Bhatnagar S, Liang J, Soriano L, Nagy TR, Dallman MF. Voluntary sucrose ingestion, like corticosterone replacement, prevents the metabolic deficits of adrenalectomy. J Neuroendocrinol 2000; 12:461-70. [PMID: 10792586 DOI: 10.1046/j.1365-2826.2000.00488.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We tested whether corticosterone replacement causes increased sucrose drinking in adrenalectomized (ADX) rats compared to sham-ADX (sham) rats. ADX rats given high doses of corticosterone drank as much sucrose as sham rats, whereas at three lower doses of corticosterone, drinking was similar between groups and was only approximately 40% of that ingested by shams. Compared to sham rats, ADX rats drinking saline, or saline and saccharin, gain weight more slowly, contain less white adipose tissue, and have higher sympathetic outflow as assessed by uncoupling protein content in brown adipose tissue. Allowing sucrose as well as saline to drink restored all of these variables to normal in ADX rats with no- or low-corticosterone. All endpoints from sucrose-drinking ADX rats with no-or low-corticosterone were indistinguishable from those in water-drinking shams. By contrast, sucrose-drinking ADX rats that were given high doses of corticosterone exhibited the usual catabolic effects of corticosterone on body weight gain and, unlike sucrose-drinking shams, were obese. We conclude that (i) high corticosterone stimulates the potability of sucrose and inhibits sympathetic stimulation of uncoupling protein; (ii) sucrose, without corticosterone, normalizes metabolic deficits in ADX rats probably through actions mediated both peripherally and by the central nervous system; and (iii) ADX rats have a distinct sucrose appetite.
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Affiliation(s)
- M E Bell
- Department of Physiology, University of California San Francisco, San Francisco, CA 94143-0444, USA
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Abstract
The nontoxic and nonshock Morrison operant technique was used to evaluate taste quality in rat and marmoset: response to a tastant test solution in pursuit of a pellet reward was dependent on making a choice between two bars that had been linked in discrimination training to qualitatively different stimulus pairs (NaCl versus either HCl, QHCl, or NH(4)Cl). The percentage distribution of bar-press responses to test stimuli showed: (1) stability of quality across 0.069-0.3 M NaCl, 0.003-0.1 M HCl, and 0.0001-0.003 M QHCl; (2) for LiCl, a quality change consistent with human reports of a "sour" to "salty" shift; (3) a suggestion that the "salty-like" quality of NH(4)Cl and NaCl are not perceptually equivalent; (4) NaNO(3) shares NaCl-like, QHCl-like, and NH(4)Cl-like components; (5) CaCl(2), KCl, and MgCl(2) share QHCl-like and NH(4)Cl-like components; and (6) responses to HCl and QHCl were not hedonically driven in the rat. Comparison of rank order correlations of single-unit firing rates to the distribution of bar-press responses for the same test stimulus concentration revealed that (7) no single level of the gustatory pathway exclusively accounts for the operant response distribution pattern to either simple or complex tastants, and (8) discriminations between tastants, one of which may be qualitatively complex, are not necessarily mediated only at levels proximal to the solitary nucleus. Thus, the Morrison discrimination technique effectively yields statements about gustatory quality without use of negative reinforcers and largely uninfluenced by tastant hedonics.
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Affiliation(s)
- D Ganchrow
- Department of Anatomy and Embryology, Sackler Faculty of Medicine, Tel Aviv University, Israel.
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Nishijo H, Ono T, Uwano T, Kondoh T, Torii K. Hypothalamic and amygdalar neuronal responses to various tastant solutions during ingestive behavior in rats. J Nutr 2000; 130:954S-9S. [PMID: 10736360 DOI: 10.1093/jn/130.4.954s] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The forebrain, including the amygdala (AM) and hypothalamus, may be a higher brain center that modulates the activity of a brainstem neural system that influences ingestive behavior via descending projections. In this study, to elucidate the characteristics of sensory information processing in the forebrain in relation to this putative connection, we recorded neuronal activity in the AM and hypothalamus [lateral hypothalamic area (LHA), medial hypothalamic area (MHA)] of rats during discrimination of conditioned sensory stimuli and the ingestion of various tastant solutions. Of 420 responsive AM neurons identified, 24 were taste responsive and located mainly in the central nucleus of the AM. Multivariate analyses of these taste neurons suggested that in the AM, taste quality is processed on the basis of palatability. In the hypothalamus, of 282 LHA and MHA neurons recorded, 144 responded to one or more conditioned auditory stimuli and/or licking of one or more solutions. Stress, which is known to influence feeding behavior, increased the mean spontaneous activity of LHA neurons but decreased the mean spontaneous neuronal activity of MHA neurons. This pattern of changes in spontaneous neuronal activity correlated with alterations in feeding behavior during stress. Furthermore, the activity of both AM and LHA neurons was modulated flexibly during conditioned associative learning. Together, the data suggest that the activity of the AM and hypothalamic neurons is altered when animals must modulate ingestive behavior by learning a new stimulus associated with food and by being exposed to stress, suggesting that these forebrain areas are important modulators of the activity of a basic neural system in the brainstem that influences ingestive behavior.
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Affiliation(s)
- H Nishijo
- Department of Physiology, Faculty of Medicine, Toyama Medical & Pharmaceutical University, Sugitani 2630, Toyama 930-0194, Japan
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