Extinction is the learned inhibition of retrieval. Recently it was shown that a brief exposure to a novel environment enhances the extinction of contextual fear in rats, an effect explainable by a synaptic tagging-and-capture process. Here we examine whether this also happens with the extinction of another fear-motivated task, inhibitory avoidance (IA), and whether it depends on dopamine acting on D1 or D5 receptors. Rats were trained first in IA and then in extinction of this task. The retention of extinction was measured 24 h later. A 5-min exposure to a novel environment 30 min before extinction training enhanced its retention. Right after exposure to the novelty, animals were given bilateral intrahippocampal infusions of vehicle (VEH), of the protein synthesis inhibitor anisomycin, of the D1/D5 dopaminergic antagonist SCH23390, of the PKA inhibitor Rp-cAMP or of the PKC inhibitor Gö6976, and of the PKA stimulator Sp-cAMP or of the PKC stimulator PMA. The novelty increased hippocampal dopamine levels and facilitated the extinction, which was inhibited by intrahippocampal protein synthesis inhibitor anisomysin, D1/D5 dopaminerdic antagonist SCH23390, or PKA inhibitor Rp-cAMP and unaffected by PKC inhibitor Gö6976; additionally, the hippocampal infusion of PKA stimulator Sp-cAMP reverts the effect of D1/D5 dopaminergic antagonist SCH 23390, but the infusion of PKC stimulator PMA does not. The results attest to the generality of the novelty effect on fear extinction, suggest that it relies on synaptic tagging and capture, and show that it depends on hippocampal dopamine D1 but not D5 receptors.dopamine | inhibitory avoidance | modulation of extinction | novelty | behavioral tagging and capture F rey and Morris (1, 2) described the enhancing influence of neuronal plastic processes [long-term potentiation (LTP) or long-term depression (LTD)] generated at one set of hippocampal synapses on LTP and LTD generated at other synapses. This influence is explainable by interactions between new proteins, called plasticity-related proteins (PRPs), at the two sets of synapses; the PRPs that tag one of them can be captured by those of others and enhance their responsiveness (3-5). Many memories rely on hippocampal LTP and LTD (1, 2, 6-11), and the "synaptic tagging-and-capture" process has been applied to the explanation of interactions between concurrent memories (11-13), among which are novelty and fear acquisition (12,14) and novelty and fear extinction (15, 16). Exposure to novelty [an open field (OF) in which they had never been before] involves two consecutive processes: its detection, which is very brief (seconds), and the immediately ensuing habituation (17), which lasts much longer; both rely on hippocampal LTD (18). With a relatively restricted time window before and/or after an extinction trial, novelty can enhance the extinction of contextual fear conditioning (CFC) lastingly (15,16). This is obviously of potential importance for exposure therapy (18-21).In rodents, the exploration of a novel environment, object, ...

THE TEACHING OF PHYSIOLOGY is indispensable in many biological and health disciplines. Physiology is one of the major components of the curriculum in a number of life science courses, including the study of life, cells, tissues, and organisms as well as their functions (7). A bigger challenge for physiology teachers is to make physiological concepts attractive to students, particularly since students of different majors are often assigned to the same class (1). The health professional, especially, needs a foundation of contextualized learning to make learning more meaningful to them, without losing quality.This foundation depends on student-centered teaching methods that assist the student in building on previous learning to prepare to be a knowledgeable future health professional. Furthermore, since physiology is sometimes a difficult course, physiology teachers need to be conscious that different teaching-learning strategies are preferable for helping different students learn (3).United States National Science Education Standards encourages teachers to assume the roles of facilitators of student learning instead of simply imparters of knowledge. Teachers/ facilitators help students become active in their learning by developing their own questions, drawing on their own experiences, analyzing and interpreting data, and drawing their own conclusions (6). However, to be successful with this approach, teachers need to design learning experiences in which scientific investigation is the norm and not the exception (6). Thus, it is not possible to improve the learning of a majority of students without improving learning about learning for a majority of teachers (4). To understand physiology completely, students need to acquire knowledge and competencies to be able to interpret complicated problems and cases (9).Thus, pedagogies that incorporate both personal and professional aspects of the physiological concepts should improve student-teacher interactions and build a strong foundation for student learning. Traditionally, physiology has been taught as a classroom course, with a mixture of lecture and laboratory experiences to introduce concepts (2). The objective of this report is to reflect on the experience of enhancing physiology teaching with seminars to contextualize the concepts of physiology into everyday health professional practice. Design of the ActivitiesBased on the principle described above, we offered seminars about human physiology related to the practice of health professionals. Seminars were offered with parallels to topics in theoretical and practical classes during extracurricular time to stimulate student participation. Participation in the seminars was not compulsory and not limited to students in the course; thus, the seminars were broadly attended throughout the institution. When we organized this activity, we hypothesized that this innovative pedagogy would improve student motivation for learning and enhance results of student learning (7).Thus, this activity offers students of different levels a...

This work examines the effects of chronic exposure to low inorganic mercury (mercury chloride, HgCl(2)) concentration on the recognition and aversive memories. Forty male Wistar rats were divided into 4 groups treated during 30 or 60 days with saline (control) or HgCl(2) doses. After treated the animals were tested considering object recognition and inhibitory avoidance behavioral memory paradigms. Elevated plus maze, open field and tail flick tests were used to assess anxiety, locomotor and exploratory activity and pain thresholds. Only exposure for 60 days to HgCl(2) induced in memory deficits quantified in the object recognition task. In the inhibitory avoidance all the animals exposed to mercury (for 30 or 60 days) presented worst performance than control animals. Our results suggest that chronic exposure to low mercury chloride concentrations impairs memory formation.

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ResumoO uso de Tecnologias de Informação e Comunicação (TICs) no ambiente acadêmico na área biomédica tem ganhado muita importância, seja pela sua capacidade de complementar o entendimento da disciplina obtido em sala de aula, seja pela facilidade de acesso, ou por tornar mais prazeroso o processo de aprendizagem, uma vez que estas ferramentas estão presentes no cotidiano dos acadêmicos e utilizam uma linguagem simples. Considerando o exposto, este estudo objetiva relatar a experiência de construção de objetos de aprendizagem em fisiologia humana como uma ferramenta de facilitação do aprendizado, bem como discutir o impacto desta metodologia de ensino. Palavras