RESUMO
Long-term memory is achieved through a consolidation process where structural and molecular changes integrate information into a stable memory. However, environmental conditions constantly change, and organisms must adapt their behavior by updating their memories, providing dynamic flexibility for adaptive responses. Consequently, novel stimulation/experiences can be integrated during memory retrieval; where consolidated memories are updated by a dynamic process after the appearance of a prediction error or by the exposure to new information, generating edited memories. This review will discuss the neurobiological systems involved in memory updating including recognition memory and emotional memories. In this regard, we will review the salient and emotional experiences that promote the gradual shifting from displeasure to pleasure (or vice versa), leading to hedonic or aversive responses, throughout memory updating. Finally, we will discuss evidence regarding memory updating and its potential clinical implication in drug addiction, phobias, and post-traumatic stress disorder.
RESUMO
Parental burnout is a unique and context-specific syndrome resulting from a chronic imbalance of risks over resources in the parenting domain. The current research aims to evaluate the psychometric properties of the Spanish version of the Parental Burnout Assessment (PBA) across Spanish-speaking countries with two consecutive studies. In Study 1, we analyzed the data through a bifactor model within an Exploratory Structural Equation Modeling (ESEM) on the pooled sample of participants (N = 1,979) obtaining good fit indices. We then attained measurement invariance across both gender and countries in a set of nested models with gradually increasing parameter constraints. Latent means comparisons across countries showed that among the participants' countries, Chile had the highest parental burnout score, likewise, comparisons across gender evidenced that mothers displayed higher scores than fathers, as shown in previous studies. Reliability coefficients were high. In Study 2 (N = 1,171), we tested the relations between parental burnout and three specific consequences, i.e., escape and suicidal ideations, parental neglect, and parental violence toward one's children. The medium to large associations found provided support for the PBA's predictive validity. Overall, we concluded that the Spanish version of the PBA has good psychometric properties. The results support its relevance for the assessment of parental burnout among Spanish-speaking parents, offering new opportunities for cross-cultural research in the parenting domain.
RESUMO
Yawning is a stereotypical behavior pattern commonly associated with other behaviors such as grooming, sleepiness, and arousal. Several differences in behavioral and neurochemical characteristics have been described in high-yawning (HY) and low-yawning (LY) sublines from Sprague-Dawley (SD) rats that support they had changes in the neural mechanism between sublines. Differences in behavior and neurochemistry observed in yawning sublines could also overlap in processes needed during taste learning, particularly during conditioned taste aversion (CTA) and its latent inhibition. Therefore, the aim of this study was to analyze taste memory differences, after familiarization to novel or highly sweet stimuli, between yawning sublines and compare them with outbred SD rats. First, we evaluated changes in appetitive response during long-term sugar consumption for 14 days. Then, we evaluated the latent inhibition of CTA strength induced by this long pre-exposure, and we also measured aversive memory extinction rate. The results showed that SD rats and the two sublines developed similar CTA for novel sugar and significantly stronger appetitive memory after long-term sugar exposure. However, after 14 days of sugar exposure, HY and LY sublines were unable to develop latent inhibition of CTA after two acquisition trials and had a slower aversive memory extinction rate than outbreed rats. Thus, the inability of the HY and LY sublines to develop latent inhibition of CTA after long-term sugar exposure could be related to the time/context processes involved in long-term appetitive re-learning, and in the strong inbreeding that characterizes the behavioral traits of these sublines, suggesting that inbreeding affects associative learning, particularly after long-term exposure to sweet stimuli which reflects high familiarization.
Assuntos
Paladar , Bocejo , Animais , Aprendizagem da Esquiva , Açúcares da Dieta , Ratos , Ratos Sprague-Dawley , AçúcaresRESUMO
Taste memory recognition is crucial for species survival; thus, the acquisition of conditioned taste aversion (CTA) protects animals against consuming poisons or toxins. In nature, food and poison are confined in the same edible item; however, in the laboratory these food constituents are usually presented separately for experimental analysis. The taste, or conditioned stimulus (CS), can be hours apart from the gastric malaise, or unconditioned stimulus (US); this extended inter-stimulus interval (ISI) allows the analysis of a particular learning phase. Evidence indicates a relevant function of glutamatergic activity in the insular cortex (IC) throughout the ISI. N-methyl-D-aspartate receptors (NMDAR) are crucial during CTA acquisition and retrieval. However, the exact participation of NMDAR in the IC during the ISI has not been demonstrated. Thus, the aim of this work was to evaluate the effects of temporal NMDAR activation during four time frames throughout the ISI of conditioned sugar aversion with bilateral injections of NMDA at a physiological dose (1⯵g/µl) in the IC, given (1) immediately before or (2) immediately after sugar presentation, or (3) immediately before or (4) immediately after LiCl i.p. injection. The results showed that NMDAR activation in the IC had a specific ISI effect during CTA acquisition, increasing aversive memory formation and delaying extinction only after CS presentation. Overall, these results demonstrate that NMDAR in the IC have a particular enhancing associative effect after CS and suggest that there is a precise coincidence in neurochemical events in the IC that correlates with the stimulus to be associated and the glutamate NMDAR activity that must be finely tuned in the ISI during CTA acquisition.
Assuntos
Aprendizagem da Esquiva/fisiologia , Córtex Cerebral/fisiologia , Condicionamento Clássico/fisiologia , Receptores de N-Metil-D-Aspartato/fisiologia , Percepção Gustatória/fisiologia , Animais , Aprendizagem da Esquiva/efeitos dos fármacos , Córtex Cerebral/efeitos dos fármacos , Condicionamento Clássico/efeitos dos fármacos , Agonistas de Aminoácidos Excitatórios/administração & dosagem , Extinção Psicológica/efeitos dos fármacos , Extinção Psicológica/fisiologia , Masculino , N-Metilaspartato/administração & dosagem , Ratos Wistar , Receptores de N-Metil-D-Aspartato/agonistas , Fatores de TempoRESUMO
The medial prefrontal cortex (mPFC) has reciprocal projections with many cerebral structures that are crucial in the control of food ingestion behavior and reward processing; Thus the mPFC has an important function in taste memory recognition. Previous results indicate that long-term consumption of sugar produces changes in appetitive re-learning and suggest that this could trigger an escalating consumption due to the inability to learn new negative consequences related to the same taste. Further evidence suggests that general identity reward value could be encoded in the mPFC. Therefore, the purpose of this study was to evaluate in rats whether after 21 days of sugar consumption the increase in sweet taste preference and latent inhibition of conditioned taste aversion (CTA) were affected differentially by pharmacological activation or blockage of dopaminergic and ß-adrenergic receptors, in the mPFC, during CTA acquisition. Results showed that after long-term sugar exposure, mPFC activation of ß-adrenergic receptors with clenbuterol delayed aversive memory extinction, but the blockade with propranolol or activation of dopaminergic receptors with apomorphine increased CTA latent inhibition and accelerated aversive memory extinction only after acute sugar exposure. Only dopaminergic blockade with haloperidol prevented sweet taste preference expression after long-term sugar consumption, increased CTA latent inhibition and accelerated extinction after acute sugar exposure. Taken together, the present data provide evidence that catecholaminergic receptors in the mPFC after prolonged sugar consumption underwent functional changes related to re-learning and new aversive taste learning.
Assuntos
Aprendizagem da Esquiva/efeitos dos fármacos , Memória/efeitos dos fármacos , Córtex Pré-Frontal/efeitos dos fármacos , Açúcares/efeitos adversos , Animais , Córtex Cerebral/fisiologia , Condicionamento Clássico/fisiologia , Extinção Psicológica/efeitos dos fármacos , Masculino , Memória/fisiologia , Córtex Pré-Frontal/fisiologia , Propranolol/farmacologia , Ratos Wistar , Paladar/efeitos dos fármacos , TempoRESUMO
Taste memory depends on motivational and post-ingestional consequences after a single taste-illness pairing. During conditioned taste aversion (CTA), the taste and visceral pathways reach the nucleus of the solitary tract (NTS), which is the first relay in the CNS and has a vital function in receiving vagal chemical stimuli and humoral signals from the area postrema that receives peripheral inputs also via vagal afferent fibers. The specific aim of the present set of experiments was to determine if the NTS is involved in the noradrenergic and glutamatergic activation of the basolateral amygdala (BLA) during CTA. Using in vivo microdialysis, we examined whether chemical NTS stimulation induces norepinephrine (NE) and/or glutamate changes in the BLA during visceral stimulation with intraperitoneal (i.p.) injections of low (0.08 M) and high (0.3 M) concentrations of lithium chloride (LiCl) during CTA training. The results showed that strength of CTA can be elicited by chemical NTS stimulation (Ringer's high potassium solution; 110 mM KCl) and by intra-NTS microinjections of glutamate, immediately after, but not before, low LiCl i.p. injections that only induce a week aversive memory. However visceral stimulation (with low or high i.p. LiCl) did not induce significantly more NE release in the amygdala compared with the NE increment induced by NTS potassium depolarization. In contrast, high i.p. concentrations of LiCl and chemical NTS stimulation induced a modest glutamate sustained release, that it is not observed with low LiCl i.p. injections. These results indicate that the NTS mainly mediates the visceral stimulus processing by sustained releasing glutamate in the BLA, but not by directly modulating NE release in the BLA during CTA acquisition, providing new evidence that the NTS has an important function in the transmission of signals from the periphery to brain systems that process aversive memory formation.
Assuntos
Complexo Nuclear Basolateral da Amígdala/efeitos dos fármacos , Complexo Nuclear Basolateral da Amígdala/metabolismo , Memória/efeitos dos fármacos , Núcleo Solitário/metabolismo , Paladar/efeitos dos fármacos , Animais , Condicionamento Clássico/efeitos dos fármacos , Ácido Glutâmico/metabolismo , Injeções Intraperitoneais , Cloreto de Lítio/administração & dosagem , Cloreto de Lítio/farmacologia , Masculino , Microdiálise , Norepinefrina/metabolismo , Ratos , Ratos Sprague-Dawley , Núcleo Solitário/efeitos dos fármacos , Estimulação QuímicaRESUMO
The NTS catecholaminergic neurons, activated by a variety of afferent stimuli, are ideally situated to coordinate afferent signaling to multiple brain regions. In particular, there is evidence that systemic epinephrine injections induce a significant increase of norepinephrine (NE) in the amygdala during enhanced memory, which can be disrupted by NTS chemical blockade or interruption of vagal afferents. The present experiment was conducted to obtain information about the levels of NE release induced by activation of the whole NTS, which projects to the lateral and basolateral amygdala. Therefore, we compared NE levels before and after general stimulation of the NTS and the amygdala in anesthetized rats, without any behavioral or vagal stimulation, to find out the degree of noradrenergic activation modulated by the NTS through all its projections to the lateral and basolateral amygdala, as well as the degree of noradrenergic activation which may occur locally in the amygdala through rapid and general activation of this structure.
Assuntos
Tonsila do Cerebelo/efeitos dos fármacos , Norepinefrina/metabolismo , Cloreto de Potássio/farmacologia , Núcleo Solitário/efeitos dos fármacos , Tonsila do Cerebelo/fisiologia , Animais , Masculino , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Ratos , Ratos Sprague-Dawley , Núcleo Solitário/fisiologiaRESUMO
In recent years, our knowledge of the neurobiology of taste and smell has greatly increased; by using several learning models, we now have a better understanding of the behavioral and neurochemical basis of memory recognition. Studies have provided new evidence of some processes that depend on prior experience with the specific combination of sensory stimuli. This review contains recent research related to taste and odor recognition memory, and the goal is to highlight the role of two prominent brain structures, the insular cortex and the amygdala. These structures have an important function during learning and memory and have been associated with the differences in learning induced by the diverse degrees of emotion during taste/odor memory formation, either aversive or appetitive or when taste and odor are combined and/or potentiated.Therefore, this review includes information about certain neurochemical transmitters and their interactions during appetitive or aversive taste memory formation,taste-potentiated odor aversion memory, and conditioned odor aversion, which might be able to maintain the complex processes necessary for flavor recognition memory.
Assuntos
Aprendizagem por Associação/fisiologia , Odorantes , Reconhecimento Psicológico/fisiologia , Olfato/fisiologia , Paladar/fisiologia , Tonsila do Cerebelo/fisiologia , Animais , Córtex Cerebral/fisiologia , Humanos , Vias Neurais/fisiologia , Condutos OlfatóriosRESUMO
Recent research, using several experimental models, demonstrated that the histaminergic system is clearly involved in memory formation. This evidence suggested that during different associative learning tasks, histamine receptor subtypes have opposite functions, related to the regulation of cortical cholinergic activity. Given that cortical cholinergic activity and nucleus basalis magnocellularis (NBM) integrity are needed during taste memory formation, the aim of this study was to determine the role of histamine receptors during conditioned taste aversion (CTA). We evaluated the effects of bilateral infusions of 0.5 microl of pyrilamine (100 mM), an H(1) receptor antagonist, into the NBM, or of R-alpha-methylhistamine (RAMH) (10 mM), an H(3) receptor agonist, into the insular cortex of male Sprague-Dawley rats 20 min before acquisition and/or retrieval of conditioned taste aversion. The results showed that blockade of H(1) receptors in NBM or activation of H(3) receptors in the insular cortex impairs formation but not retrieval of aversive taste memory. These results demonstrated differential roles for histamine receptors in two important areas for taste memory formation and suggest that these effects could be related with the cortical cholinergic activity modulation during CTA acquisition.
Assuntos
Núcleo Basal de Meynert/fisiologia , Condicionamento Clássico/fisiologia , Rememoração Mental/fisiologia , Receptores Histamínicos/metabolismo , Percepção Gustatória/fisiologia , Lobo Temporal/fisiologia , Animais , Núcleo Basal de Meynert/efeitos dos fármacos , Condicionamento Clássico/efeitos dos fármacos , Agonistas dos Receptores Histamínicos/farmacologia , Antagonistas dos Receptores Histamínicos H1/farmacologia , Masculino , Rememoração Mental/efeitos dos fármacos , Metilistaminas/farmacologia , Pirilamina/farmacologia , Ratos , Ratos Sprague-Dawley , Receptores Histamínicos H1/metabolismo , Receptores Histamínicos H3/metabolismo , Lobo Temporal/efeitos dos fármacos , Fatores de TempoRESUMO
Taste memory has been a useful model for studying memory formation; using different approaches ranging from lesion studies, analysis of receptor and neurotransmitter activity, and measurement of intracellular signaling mechanisms or gene expression, it has been possible to describe processes which may be involved in several types of memory. Taste memory includes the recognition of a taste as well as its characteristics related to the hedonic value, degree of familiarity, and the nutritive or toxic properties associated with that taste. In terms of evolutionary adaptation, taste memory is necessary for the proper identification of available nutritive foods and, of course, is essential to avoid deadly toxins. This review summarizes the current knowledge of taste memory, describing the evidence obtained using non-associative and associative taste learning models by manipulating the different structures involved in the formation and expression of taste memory. Pharmacological, biochemical, and molecular data are shown for each structure and subsequently current theories are presented about possible inter-structural interactions taking part in taste memory formation. Finally, we describe how the study of taste memory can reveal basic mechanisms of learning, raising issues that might apply to learning processes in general.
Assuntos
Encéfalo/fisiologia , Memória/fisiologia , Percepção Gustatória/fisiologia , Animais , Aprendizagem/fisiologia , Percepção Gustatória/genéticaRESUMO
Acetylcholine and norepinephrine have been implicated during different kinds of social recognition that involves olfactory memory formation. For example, blockade of muscarinic and beta-adrenergic receptors has been shown to impair short-term memory of both socially relevant as well as of neutral odors. However, previous studies have not explicitly compared the role of cholinergic and adrenergic modulation in long-term memory for socially relevant odor vs. incidental odor stimuli. In this work, we studied the function of muscarinic and beta-adrenergic receptors during acquisition and/or consolidation of a novel odor and during the retrieval of a familiar odor. The effects of systemic injections of scopolamine and propranolol, before and after presentation of estrous urine odor or mint odor, were evaluated by a long-term odor habituation task. The results demonstrated that scopolamine disrupts memory acquisition and/or consolidation of mint odor, and did not have any effect during retrieval of mint odor memory. Conversely, scopolamine disrupts memory consolidation and retrieval of estrous odor, depending on the dose applied. Propranolol injections have no effect on acquisition or consolidation for mint or estrous odor, but disrupt memory retrieval of familiar odor regarding their social/sexual or neutral content. These results demonstrate that muscarinic receptors are required differentially during long-term odor memory formation and for familiar odor recognition depending on the socially relevant content of the stimulus. Furthermore, the beta-adrenergic system could play an important role in memory recognition for familiar odors, regardless of the sexual/social or neutral content of the stimuli.
Assuntos
Memória/fisiologia , Odorantes , Receptores Adrenérgicos beta/metabolismo , Receptores Muscarínicos/metabolismo , Percepção Social , Antagonistas Adrenérgicos beta/administração & dosagem , Análise de Variância , Animais , Antagonistas Colinérgicos/administração & dosagem , Ciclo Estral/fisiologia , Habituação Psicofisiológica/efeitos dos fármacos , Habituação Psicofisiológica/fisiologia , Masculino , Memória/efeitos dos fármacos , Antagonistas Muscarínicos/administração & dosagem , Propranolol/administração & dosagem , Ratos , Ratos Sprague-Dawley , Reconhecimento Psicológico/efeitos dos fármacos , Reconhecimento Psicológico/fisiologia , Escopolamina/administração & dosagem , Comportamento Sexual Animal/efeitos dos fármacos , Comportamento Sexual Animal/fisiologia , UrinaRESUMO
The importance of central beta-adrenergic system has been essentially investigated in aversive/emotional learning tasks. However, recent data suggest that the beta-adrenergic system is also required for incidental taste learning. In the present study we evaluated in rats whether beta-adrenergic receptor activity is required for taste habituation, an incidental taste learning, and also for conditioned taste aversion (CTA) learning, an associative learning. To address this issue, a low dose of the beta-adrenergic antagonist propranolol was infused before learning in either the basolateral amygdala (BLA) or the insular cortex (IC), two forebrain areas reported to play a key role in taste memory formation. Incidental taste learning was assessed using a single presentation of the sweet taste saccharin 0.1%, which is sufficient to increase saccharin consumption (relative to water baseline) during a second presentation. CTA was assessed by pairing the first saccharin 0.1% presentation with a delayed gastric malaise, thus causing a decrease in saccharin consumption (relative to water baseline) during a second presentation. Propranolol infusion in BLA (1microg/0.2microl) or IC (2.5microg/0.5microl) before the first taste exposure impaired incidental taste learning but did not affect CTA. These results highlight the important role played by the beta-adrenergic receptor activation in cortical and amygdaloid structures during taste learning. Moreover, they are the first to suggest that incidental learning is more sensitive to blockade of noradrenergic system than associative learning.
Assuntos
Antagonistas Adrenérgicos beta/farmacologia , Tonsila do Cerebelo/fisiologia , Aprendizagem por Associação/efeitos dos fármacos , Córtex Cerebral/fisiologia , Propranolol/farmacologia , Receptores Adrenérgicos beta/fisiologia , Tonsila do Cerebelo/efeitos dos fármacos , Animais , Aprendizagem por Associação/fisiologia , Córtex Cerebral/efeitos dos fármacos , Condicionamento Psicológico/efeitos dos fármacos , Condicionamento Psicológico/fisiologia , Habituação Psicofisiológica/efeitos dos fármacos , Habituação Psicofisiológica/fisiologia , Masculino , Microinjeções , Norepinefrina/fisiologia , Ratos , Ratos Wistar , PaladarRESUMO
Experiences with a high emotional content (aversive) tend to be stored as long-term memories; however, there are also contextual recollections, which form a significant part of our memories. Different research has shown that the insular cortex (IC) plays an important role during aversive memory formation, yet its role during incidental/non-aversive learning like pre-exposure contextual memory formation has received little attention. The objective of this research was to establish the role of cholinergic activity in the IC through its muscarinic receptors during the formation of inhibitory avoidance (IA) memory, as well as during pre-exposure contextual memory, using a paradigm such as latent inhibition (LI). Rats with bilateral cannulae directed into the IC were trained in the LI paradigm of IA or IA task alone. The muscarinic antagonist receptor scopolamine was infused bilaterally into the IC 5 min before the pre-exposure into the dark chamber of the IA cage, one day before the conventional IA training or during the IA training day. During the IA test, the entrance latency into the dark chamber of the IA cage was measured as an index of contextual memory. The results showed that scopolamine infused before and after IA training disrupts inhibitory avoidance memory. Also, it showed that the pre-exposed saline-infused animals (LI) had a lower entrance latency compared to the group not pre-exposed (IA). However, the group that received scopolamine into the IC before, but not after, the pre-exposure to the dark chamber, presented a similar latency to the IA group, showing a blockade of the latent inhibition of the IA. These results suggest that cholinergic activity in the insular cortex is necessary during the acquisition and consolidation of avoidance memory, but appears necessary only during the acquisition of pre-exposure non-aversive contextual memory.
Assuntos
Aprendizagem da Esquiva/fisiologia , Córtex Cerebral/metabolismo , Fibras Colinérgicas/metabolismo , Receptores Muscarínicos/metabolismo , Reconhecimento Psicológico/fisiologia , Análise de Variância , Animais , Aprendizagem da Esquiva/efeitos dos fármacos , Córtex Cerebral/efeitos dos fármacos , Fibras Colinérgicas/efeitos dos fármacos , Meio Ambiente , Inibição Psicológica , Masculino , Microinjeções , Antagonistas Muscarínicos/administração & dosagem , Ratos , Ratos Wistar , Tempo de Reação/efeitos dos fármacos , Tempo de Reação/fisiologia , Receptores Muscarínicos/efeitos dos fármacos , Reconhecimento Psicológico/efeitos dos fármacos , Escopolamina/administração & dosagem , Comportamento Espacial/efeitos dos fármacos , Comportamento Espacial/fisiologia , Estatísticas não ParamétricasRESUMO
There is a large body of evidence suggesting that cholinergic activity is involved in memory processes. It seems that cholinergic activity is essential to learn several tasks and recent works suggest that acetylcholine plays an important role during the early stages of memory formation. In this review, we will discuss the results related to taste memory formation, focusing particularly on the conditioned taste aversion paradigm. We will first give evidence that nucleus basalis magnocellularis is involved in taste memory formation, due to its cholinergic projections. We then show that the cholinergic activity of the insular (gustatory) cortex is related to the taste novelty, and that the cholinergic signals initiated by novelty are crucial for taste memory formation. Then we present recent data indicating that cortical activation of muscarinic receptors is necessary for taste trace encoding, and also for its consolidation under certain circumstances. Finally, interactions between the cholinergic and other neuromodulatory systems inducing intracellular mechanisms related to plastic changes will be proposed as important processes underlying gustatory memory trace storage.
Assuntos
Memória de Curto Prazo/fisiologia , Receptores Colinérgicos/fisiologia , Paladar/fisiologia , Tonsila do Cerebelo/efeitos dos fármacos , Tonsila do Cerebelo/metabolismo , Córtex Cerebral/metabolismo , Humanos , Memória de Curto Prazo/efeitos dos fármacos , Antagonistas Muscarínicos/administração & dosagem , Antagonistas Muscarínicos/farmacologia , Plasticidade Neuronal/efeitos dos fármacos , Transtornos Fóbicos/metabolismo , Receptores Colinérgicos/metabolismo , Receptores Muscarínicos/metabolismo , Receptores Muscarínicos/fisiologia , Receptores de N-Metil-D-Aspartato/efeitos dos fármacos , Receptores de N-Metil-D-Aspartato/metabolismo , Escopolamina/administração & dosagem , Escopolamina/farmacologia , Paladar/efeitos dos fármacosRESUMO
A number of studies have implicated cholinergic activity in the mediation of learning and memory processes. However, the specific role of muscarinic receptors in memory formation mechanisms is less known. The aim of the present study is to evaluate the effects of muscarinic antagonist M2 presynaptic receptor, AFDX-116 (0.5mM) and M1 and M3 post-synaptic receptor pirenzepine (100mM), as well as a non-selective muscarinic antagonist, scopolamine (136mM), in the insular cortex (IC) during acquisition and retrieval of conditioned taste aversion (CTA). In addition, we evaluate the effects of those antagonists in cortical ACh release by in vivo microdialysis and the effects on the induction of in vivo LTP in the BLA-IC projection. The results showed that the cortical microinjections of scopolamine and pirenzepine, but not AFDX-116, produced significant disruption in the acquisition of CTA, without effects during retrieval. Microinjections of scopolamine and AFDX-116 produced significant cortical ACh release, while infusions of pirenzepine did not produce any release. Application of scopolamine and pirenzepine diminished induction of LTP in the BLA-IC projection, but not AFDX-116, as compared with vehicle. The induction of BLA-CI LTP seems to be modulated by post-synaptic muscarinic acetylcholine receptors and not by pre-synaptic muscarinic receptors. These results suggest a differential involvement of cholinergic receptors during acquisition and retrieval of aversive memory formation, as well as a differential role of muscarinic receptors in the biochemical and electrophysiological processes that may underlay aversive memory.
Assuntos
Córtex Cerebral/fisiologia , Memória/fisiologia , Antagonistas Muscarínicos/farmacologia , Pirenzepina/análogos & derivados , Receptores Muscarínicos/fisiologia , Paladar/fisiologia , Animais , Aprendizagem da Esquiva/efeitos dos fármacos , Aprendizagem da Esquiva/fisiologia , Córtex Cerebral/efeitos dos fármacos , Condicionamento Operante/efeitos dos fármacos , Condicionamento Operante/fisiologia , Potenciação de Longa Duração/efeitos dos fármacos , Masculino , Memória/efeitos dos fármacos , Microdiálise , Microinjeções , Pirenzepina/farmacologia , Ratos , Ratos Wistar , Receptores Muscarínicos/efeitos dos fármacos , Receptores Pré-Sinápticos/efeitos dos fármacos , Receptores Pré-Sinápticos/fisiologia , Escopolamina/farmacologia , Paladar/efeitos dos fármacosRESUMO
OBJECTIVE: The aim of this study was to evaluate the resistance to fracture of intact and restored human maxillary premolars. METHOD AND MATERIALS: Thirty noncarious human maxillary premolars, divided into three groups of 10, were submitted to mechanical tests to evaluate their resistance to fracture. Group 1 consisted of intact teeth. Teeth in group 2 received mesio-occlusodistal cavity preparations and were restored with direct resin composite restorations. Teeth in group 3 received mesio-occlusodistal cavity preparations and were restored with ceromer inlays placed with the indirect technique. After restoration, teeth were stored at 37 degrees C for 24 hours and then thermocycled for 500 cycles at temperatures of 5 degrees C and 55 degrees C. RESULTS: Statistical analysis revealed that group 3 (178.765 kgf) had a significantly greater maximum rupture load than did group 1 (120.040 kgf). There was no statistically significant difference between groups 1 and 2 or between groups 2 and 3. CONCLUSION: Class II cavity preparations restored with indirect ceromer inlays offered greater resistance to fracture than did intact teeth. The fracture resistance of teeth restored with resin composite was not significantly different from that of either the ceromer or intact teeth.
Assuntos
Dente Pré-Molar/fisiopatologia , Cerâmica/química , Resinas Compostas/química , Preparo da Cavidade Dentária/classificação , Restauração Dentária Permanente/classificação , Fraturas dos Dentes/fisiopatologia , Condicionamento Ácido do Dente , Análise de Variância , Polimento Dentário , Restauração Dentária Permanente/métodos , Adesivos Dentinários/química , Humanos , Restaurações Intracoronárias/classificação , Restaurações Intracoronárias/métodos , Maxila , Cimentos de Resina/química , Estatística como Assunto , Estresse Mecânico , Propriedades de Superfície , Temperatura , Termodinâmica , Fatores de TempoRESUMO
El presente trabajo tuvo como objetivo elaborar y vaidar material para, impartir educacion alimentaria nutricional en las comunidades de Copalapaya, Choquenaira, Callisaya y Marumaya pertenecientes a la provincia Ingavi. Con material exclusivo para el área rural y con temáticas dirigidas tanto amujeres, hombres , niños, tal material fue elaborado con la participación de toda la comunidad, donde cada uno de ellos pusieron sus habilidades y dieron sus ideas para mejorar el material y sobre todo solicitaron que los dibujos sean tan fieles a la realidad como sea posible...