Health and Pleasure in Consumers' Dietary Food Choices: Individual Differences in the Brain's Value System

Taking into account how people value the healthiness and tastiness of food at both the behavioral and brain levels may help to better understand and address overweight and obesity-related issues. Here, we investigate whether brain activity in those areas involved in self-control may increase significantly when individuals with a high body-mass index (BMI) focus their attention on the taste rather than on the health benefits related to healthy food choices. Under such conditions, BMI is positively correlated with both the neural responses to healthy food choices in those brain areas associated with gustation (insula), reward value (orbitofrontal cortex), and self-control (inferior frontal gyrus), and with the percent of healthy food choices. By contrast, when attention is directed towards health benefits, BMI is negatively correlated with neural activity in gustatory and reward-related brain areas (insula, inferior frontal operculum). Taken together, these findings suggest that those individuals with a high BMI do not necessarily have reduced capacities for self-control but that they may be facilitated by external cues that direct their attention toward the tastiness of healthy food. Thus, promoting the taste of healthy food in communication campaigns and/or food packaging may lead to more successful self-control and healthy food behaviors for consumers with a higher BMI, an issue which needs to be further researched

Spatiotemporal neural characterization of prediction error valence and surprise during reward learning in humans

Reward learning depends on accurate reward associations with potential choices. These associations can be attained with reinforcement learning mechanisms using a reward prediction error (RPE) signal (the difference between actual and expected rewards) for updating future reward expectations. Despite an extensive body of literature on the influence of RPE on learning, little has been done to investigate the potentially separate contributions of RPE valence (positive or negative) and surprise (absolute degree of deviation from expectations). Here, we coupled single-trial electroencephalography with simultaneously acquired fMRI, during a probabilistic reversal-learning task, to offer evidence of temporally overlapping but largely distinct spatial representations of RPE valence and surprise. Electrophysiological variability in RPE valence correlated with activity in regions of the human reward network promoting approach or avoidance learning. Electrophysiological variability in RPE surprise correlated primarily with activity in regions of the human attentional network controlling the speed of learning. Crucially, despite the largely separate spatial extend of these representations our EEG-informed fMRI approach uniquely revealed a linear superposition of the two RPE components in a smaller network encompassing visuo mnemonic and reward areas. Activity in this network was further predictive of stimulus value updating indicating a comparable contribution of both signals to reward learning

Condiciones ecológicas del cultivo del trigo en la Argentina con especial consideración del problema de las variedades y creación de tipos uniformes para la exportación

1º Se examinan las condiciones ecológicas para el cultivo de trigo en la Argentina, y se establecen 5 zonas trigueras que se describen sintéticamente. 2° Sobre la base de los ensayos realizados entre variedades, se examina el comportamiento de un cierto número de variedades típicas en las 5 zonas establecidas, tomándose por base — para la apreciación de las mismas — los ensayos de épocas de siembra realizados en Santa Catalina durante tres años. El cultivo de trigo con riego, como igualmente el cultivo de trigos duros (durum), no fué tomado en consideración en el presente trabajo, dado su insignificancia para los fines de exportación. 3º Como resultado de este estudio se deduce el siguiente juicio: el problema de las variedades para toda la extensa zona triguera argentina es muy simple, por cuanto, con 3 distintos tipos de variedades, es posible llenar las exigencias naturales del cultivo de referencia. 4º Se refiere a la evolución de las condiciones de los tipos de exportación argentinos bajo la influencia de las variedades seleccionadas, en lugar de los trigos comunes cultivados anteriormente, y también a la apreciación de sus aptitudes panaderas. Las pruebas de panificación directa y la determinación de las propiedades mecánicas de las pastas, efectuadas simultáneamente, parecen ser las más indicadas piara fijar la diferencia que existe entre los «trigos de fuerza para mezcla», que no se prestan para ser panificados directamente, y los «trigos de relleno» que producen excelente pan en panificación directa. 5° Con esta diferenciación de las variedades ya existentes y con la posibilidad de crear en poco tiempo las variedades que aún pudieran faltar, es posible mejorar en mucho la calidad de los trigos de exportación argentinos, utilizando para ello el material fitotécnico existente en las Estaciones Experimentales, aprovechando las ya estudiadas condiciones ecológicas, empleando las medidas de organización necesarias, y velando por la constancia de los tipos de exportación, una vez creados los mismos.Facultad de Ciencias Agrarias y Forestale

Decomposition of time-dependent fluorescence signals reveals codon-specific kinetics of protein synthesis

During protein synthesis, the nascent peptide chain traverses the peptide exit tunnel of the ribosome. We monitor the co-translational movement of the nascent peptide using a fluorescent probe attached to the N-terminus of the nascent chain. Due to fluorophore quenching, the time-dependent fluorescence signal emitted by an individual peptide is determined by co-translational events, such as secondary structure formation and peptide-tunnel interactions. To obtain information on these individual events, the measured ensemble fluorescence signal has to be decomposed into position-dependent intensities. Here, we describe mRNA translation as a Markov process with specific fluorescence intensities assigned to the different states of the process. Combining the computed stochastic time evolution of the translation process with a sequence of observed ensemble fluorescence time courses, we compute the unknown position-specific intensities and obtain detailed information on the kinetics of the translation process. In particular, we find that translation of poly(U) mRNAs dramatically slows down at the fourth UUU codon. The method presented here detects subtle differences in the position-specific fluorescence intensities and thus provides a novel approach to study translation kinetics in ensemble experiments