The Role of Gamma-Band Activity in the Representation of Faces: Reduced Activity in the Fusiform Face Area in Congenital Prosopagnosia

Congenital prosopagnosia (CP) describes an impairment in face processing that is presumably present from birth. The neuronal correlates of this dysfunction are still under debate. In the current paper, we investigate high-frequent oscillatory activity in response to faces in persons with CP. Such neuronal activity is thought to reflect higher-level representations for faces.Source localization of induced Gamma-Band Responses (iGBR) measured by magnetoencephalography (MEG) was used to establish the origin of oscillatory activity in response to famous and unknown faces which were presented in upright and inverted orientation. Persons suffering from congenital prosopagnosia (CP) were compared to matched controls.Corroborating earlier research, both groups revealed amplified iGBR in response to upright compared to inverted faces predominately in a time interval between 170 and 330 ms and in a frequency range from 50-100 Hz. Oscillatory activity upon known faces was smaller in comparison to unknown faces, suggesting a "sharpening" effect reflecting more efficient processing for familiar stimuli. These effects were seen in a wide cortical network encompassing temporal and parietal areas involved in the disambiguation of homogenous stimuli such as faces, and in the retrieval of semantic information. Importantly, participants suffering from CP displayed a strongly reduced iGBR in the left fusiform area compared to control participants.In sum, these data stress the crucial role of oscillatory activity for face representation and demonstrate the involvement of a distributed occipito-temporo-parietal network in generating iGBR. This study also provides the first evidence that persons suffering from an agnosia actually display reduced gamma band activity. Finally, the results argue strongly against the view that oscillatory activity is a mere epiphenomenon brought fourth by rapid eye-movements (micro saccades)

Age and the Neural Network of Personal Familiarity

BACKGROUND: Accessing information that defines personally familiar context in real-world situations is essential for the social interactions and the independent functioning of an individual. Personal familiarity is associated with the availability of semantic and episodic information as well as the emotional meaningfulness surrounding a stimulus. These features are known to be associated with neural activity in distinct brain regions across different stimulus conditions (e.g., when perceiving faces, voices, places, objects), which may reflect a shared neural basis. Although perceiving context-rich personal familiarity may appear unchanged in aging on the behavioral level, it has not yet been studied whether this can be supported by neuroimaging data. METHODOLOGY/PRINCIPAL FINDINGS: We used functional magnetic resonance imaging to investigate the neural network associated with personal familiarity during the perception of personally familiar faces and places. Twelve young and twelve elderly cognitively healthy subjects participated in the study. Both age groups showed a similar activation pattern underlying personal familiarity, predominantly in anterior cingulate and posterior cingulate cortices, irrespective of the stimulus type. The young subjects, but not the elderly subjects demonstrated an additional anterior cingulate deactivation when perceiving unfamiliar stimuli. CONCLUSIONS/SIGNIFICANCE: Although we found evidence for an age-dependent reduction in frontal cortical deactivation, our data show that there is a stimulus-independent neural network associated with personal familiarity of faces and places, which is less susceptible to aging-related changes

Passive and Motivated Perception of Emotional Faces: Qualitative and Quantitative Changes in the Face Processing Network

Emotionally expressive faces are processed by a distributed network of interacting sub-cortical and cortical brain regions. The components of this network have been identified and described in large part by the stimulus properties to which they are sensitive, but as face processing research matures interest has broadened to also probe dynamic interactions between these regions and top-down influences such as task demand and context. While some research has tested the robustness of affective face processing by restricting available attentional resources, it is not known whether face network processing can be augmented by increased motivation to attend to affective face stimuli. Short videos of people expressing emotions were presented to healthy participants during functional magnetic resonance imaging. Motivation to attend to the videos was manipulated by providing an incentive for improved recall performance. During the motivated condition, there was greater coherence among nodes of the face processing network, more widespread correlation between signal intensity and performance, and selective signal increases in a task-relevant subset of face processing regions, including the posterior superior temporal sulcus and right amygdala. In addition, an unexpected task-related laterality effect was seen in the amygdala. These findings provide strong evidence that motivation augmentsco-activity among nodes of the face processing network and the impact of neural activity on performance. These within-subject effects highlight the necessity to consider motivation when interpreting neural function in special populations, and to further explore the effect of task demands on face processing in healthy brains

Intersubjetividad y consenso: apuntes sobre el debate entre Rawls y Habermas

Taking as a starting point the important critical exchange between John Rawls and Jürgen Habermas in The Journal of Philosophy in March 1995, the aim of this paper is to explore the place that consensus occupies in the foundation of the political thought of both authors. In such a way that the intersubjective character that underlies both Rawls’ theory of justice and Habermasian discourse ethics can be highlighted. The above, in fact, implies a conceptual exercise that leads to the clarification of two argumentative paths, both heirs of an own interpretation of Kant, aimed at providing a solution to the foundation of moral principles in contemporary plural societies.Teniendo como punto de partida el importante intercambio crítico entre John Rawls y Jürgen Habermas desplegado en The Journal of Philosohy en marzo de 1995, el presente escrito tiene por objetivo explorar el lugar que ocupa el consenso en la fundamentación del pensamiento político de ambos autores. De modo tal que pueda ponerse en evidencia el carácter intersubjetivo que subyace tanto en los planteos de la teoría de la justicia de Rawls como en la ética del discurso habermasiana. Lo anterior, en efecto, implica un ejercicio conceptual que decanta en el esclarecimiento de dos sendas argumentativas, ambas herederas de una interpretación de Kant, encauzadas a dar solución a la fundamentación de principios morales en las sociedades plurales contemporáneas

Prueba de ejercicio cardiopulmonar en niños sanos

Background: Cardiopulmonary exercise testing is a valuable tool for assessing the clinical condition and prognosis of patients with cardiovascular disease; it is therefore essential to have normal reference values in healthy children. Objective: The aim of this study was to perform cardiopulmonary exercise testing in healthy children to obtain reference values in our laboratories. Methods: Cardiopulmonary exercise testing was performed in 215 healthy children divided into 2 groups: A, Prepubertal and B, Pubertal. These groups were in turn divided into male and female. The test was performed on a treadmill with O2 saturation and breath-by-breath expired gas analysis with a COSMED system. Statistical analysis was performed with SPSS 17 software package. Results: The A and B groups are significantly different in age, weight, height, and body surface area. Significant differences were found between the two groups in VO2 ml/min (p <0.0000), respiratory exchange ratio (p <0.01), O2 pulse in ml/bpm (p < 0.0000) and VE/VCO2 slope (p <0.0000). In the analysis by gender there were significant differences in peak VO2 ml/kg/ min, peak VO2 ml/min, MET, VE/VCO2 slope and VO2 ml/kg/min in ventilatory anaerobic threshold. Group A also showed significant gender difference in peak heart rate. VO2 ml/min and peak O2 pulse (VO2 ml/heart rate) increased with age and body surface area. The VE/VCO2 slope decreases with age. Conclusions: The data obtained in this study allow analysis of cardiopulmonary exercise testing variables in healthy children according to age and gender. These values can be used as reference data to evaluate patients with cardiovascular disease in Argentina.Introducción: La prueba de ejercicio cardiopulmonar es una valiosa herramienta para evaluar la condición clínica y el pronóstico en pacientes con patología cardiovascular, por lo que resulta fundamental contar con valores normales de referencia en niños sanos. Objetivo: Realizar la prueba de ejercicio cardiopulmonar en niños sanos para obtener valores referenciales en nuestros laboratorios. Material y métodos: Se incluyeron 215 niños sanos, que realizaron la prueba de ejercicio cardiopulmonar. Se dividieron en dos grupos: A, prepuberal y B, puberal. Estos grupos, a su vez, se dividieron en varones y mujeres. La prueba se realizó en cinta ergométrica, con saturación de O2 y análisis de gases espirados respiración por respiración con un equipo marca COSMED. Para el análisis estadístico se utilizó el programa SPSS 17. Resultados: Los grupos A y B son significativamente diferentes en edad, peso, talla y superficie corporal. Se encontraron diferencias significativas entre los dos grupos en VO2 ml/min (p < 0,0000), cociente de intercambio respiratorio (p < 0,01), pulso de O2 ml/lpm (p < 0,0000) y pendiente VE/VCO2 (p < 0,0000). En el análisis por sexo se encontraron diferencias significativas en VO2 ml/kg/min pico, VO2 ml/min pico, MET, pendiente VE/VCO2 y VO2 ml/kg/min en umbral anaeróbico ventilatorio. En el grupo A se observó además una diferencia significativa por sexo en la frecuencia cardíaca pico. El VO2 ml/min y el pulso de O2 pico (VO2 ml/frecuencia cardíaca) aumentaron con la superficie corporal y con la edad. La pendiente VE/VCO2 disminuye con la edad. Conclusiones: Los datos obtenidos en este estudio permiten el análisis de variables de la prueba de ejercicio cardiopulmonar en niños sanos de acuerdo con edad y sexo. Estos valores se podrán utilizar como datos referenciales para evaluar pacientes con enfermedad cardiovascular en la Argentina

Recognition Memory for Faces and Scenes

Previous studies have suggested that face memory is unique; however, evidence is inconclusive. To further explore this issue, we investigated recognition memory for unfamiliar faces and scenes. Participants (n = 123) intentionally memorized the stimuli and then engaged in recognition tests. Recognition was measured following short (20 minutes) and long (3 weeks) retention intervals. Encoding strategies and intelligence were also measured. Recognition memory performance for faces was higher than that for scenes at both short and long intervals; however, the effect of retention interval was different between faces and scenes. A relationship between encoding strategies and memory performance was found for scenes but not for faces. The relationship between intelligence and memory performance also differed between faces and scenes. These results suggest that memory for faces is more robust and uses different cognitive mechanisms than memory for scenes

Remote memory in temporal lobe epilepsy

International audiencePurpose: The present study aims at characterizing remote memory in patients with temporal lobe epilepsy (TLE); it also considers the impact of its most important variables (lat-eralization of the lesion, duration of epilepsy, age at onset, and seizure frequency) on remote memory. Methods: We examined the performance of 38 patients with unilateral TLE (19 right TLE and 19 left TLE) and 35 healthy subjects on six remote memory tasks. Memory for personal events was assessed by using the Autobiographical Memory Interview and the Modified Crovitz Test. Memory for public events was evaluated by means of photographs of famous faces and famous scenes, questions about famous events, and the Dead/Alive Test. Results: Both right-TLE and left-TLE groups had impaired memory for autobiographic episodes and public events relative to normal subjects. In contrast, personal semantic memory was preserved. In addition, an effect of laterality was recorded, with right-TLE patients obtaining significantly better scores than left-TLE patients on every test. Duration of epilepsy, age at onset, and seizure frequency did not influence performance on remote memory measures. Conclusions: The comprehensive neuropsychological study of 38 TLE patients showed that this neurologic condition affects remote memory systems differently. We discuss the different factors that could account for this pattern of performance on the bases of both functional brain organization and memory theories