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RESUMEN Objetivo: Comparar el efecto antibacteriano in vitro de muestras de miel de Apis mellifera producida en la Costa, Sierra y Selva contra Streptococcus mutans ATCC 25175. Material y métodos: Se evaluó el efecto en 3 grupos distribuidos en concentraciones de 100%, 50% y 25% para cada miel. Se hicieron 5 repeticiones por grupo experimental. La sensibilidad bacteriana se evaluó mediante el método de difusión en pozo. El espécimen bacteriano fue reactivado en caldo nutritivo, para inocularlo en cultivo Agar Cerebro Corazón. Resultados: Al enfrentar el microorganismo a las mieles de abeja, se obtuvo halos promedios de inhibición de 27,84 mm y 14,38 mm para las concentraciones de 100% y 50% de la miel de abeja de origen de sierra. Conclusión: sin embargo, las mieles de abeja de origen costa y selva no presentaron halos de inhibición. Se concluye que la miel de abeja de origen de Sierra al 100% y 50% tienen efecto antibacteriano sobre S. mutans ATCC 25175

Model-free learning creates stimulus-response associations. But what constitutes a stimulus? Are there limits to types of stimuli a model-free or habitual system can operate over? Most experiments on reward learning in humans and animals have used discrete sensory stimuli, but there is no algorithmic reason that model-free learning should be restricted to external stimuli, and recent theories have suggested that model-free processes may operate over highly abstract concepts and goals. Our study aimed to determine whether model-free learning processes can operate over environmental states defined by information held in working memory. Specifically, we tested whether or not humans can learn explicit temporal patterns of individually uninformative cues in a model-free manner. We compared the data from human participants in a reward learning paradigm using (1) a simultaneous symbol presentation condition or (2) a sequential symbol presentation condition, wherein the same visual stimuli were presented simultaneously or as a temporal sequence that required working memory. We found a significant effect of reward on human behavior in the sequential presentation condition, indicating that model-free learning can operate on information stored in working memory. Further analyses, however, revealed that the behavior of the participants contradicts the basic assumptions of our hypotheses, and it is possible that the observed effect of reward was generated by model-based rather than model-free learning. Thus it is not possible to draw any conclusions from out study regarding model-free learning of temporal sequences held in working memory. We conclude instead that careful thought should be given about how to best explain two-stage tasks to participants.