Connectivity-based parcellation of the human frontal polar cortex

The frontal pole corresponds to Brodmann area (BA) 10, the largest single architectonic area in the human frontal lobe. Generally, BA10 is thought to contain two or three subregions that subserve broad functions such as multitasking, social cognition, attention, and episodic memory. However, there is a substantial debate about the functional and structural heterogeneity of this large frontal region. Previous connectivity-based parcellation studies have identified two or three subregions in the human frontal pole. Here, we used diffusion tensor imaging to assess structural connectivity of BA10 in 35 healthy subjects and delineated subregions based on this connectivity. This allowed us to determine the correspondence of structurally based subregions with the scheme previously defined functionally. Three subregions could be defined in each subject. However, these three subregions were not spatially consistent between subjects. Therefore, we accepted a solution with two subregions that encompassed the lateral and medial frontal pole. We then examined resting-state functional connectivity of the two subregions and found significant differences between their connectivities. The medial cluster was connected to nodes of the default-mode network, which is implicated in internally focused, self-related thought, and social cognition. The lateral cluster was connected to nodes of the executive control network, associated with directed attention and working memory. These findings support the concept that there are two major anatomical subregions of the frontal pole related to differences in functional connectivity

The convergence of emerging groups via Web 2.0 social networking sites

In the 1980s and ‘90s online communities were said to have freed us from geographical and time constraints. Yet they were defined by the virtual space used to host people’s interactions. Online communities were artificially constructed each with a distinctive theme agreed by their designers. Membership was granted by subscription. Users interested in the community’s theme joined to search for content and meet people with similar interests. In new Web 2.0 environments such as social networking sites (SNS), users sign up to the tool but not to the networks. These sites are not owned by one group of people but by many with different interests and purposes. Social networks are built by the links users create between them and strengthened by meaningful participation. Online communities can emerge from these socializations when groups of people empathize and discover similarities between them. Membership and boundaries of these communities are not defined by the space or the account but by people and participation. In this paper we present findings from ethnographic research of an online community that has emerged from converging social networks on Twitter. Face-to-face semi-structured interview data are triangulated with the results from an online questionnaire via Twitter and analysis of community discussion threads using hashtags to validate a conceptual framework of how communities form and grow via SNS. In this research we explore the different layers of use (one-to-one relationships, Twitter networks and online community), the roles individuals adopt in this emerging community, and their strategies for managing their co-existence with other networks in the same space. Furthermore we investigate how this online community has transitioned from its interest-driven origins to supporting friendship-driven interactions. We offer a contribution to knowledge in terms of providing a clearer definition of how contemporary communities are enabled by SNS, and how those communities overlap

La convergencia de grupos emergentes vía sitios sociales del establecimiento de una red del Web 2.0

Social networking site (SNS) communities emerge from socialization, when groups of people empathize and discover similarities between themselves. These communities are not defined by the place or the account but by people and participation. We validate a conceptual framework of how communities form and grow via SNS from ethnographic research of an online group that has emerged from converging social networks on Twitter. We define layers of use, the roles individuals adopt in these emerging communities, and their strategies for co-existence. This is underpinned by an exploration of how groups transition from interest-driven origins to supporting friendship-driven interactions.Las comunidades sociales del sitio del establecimiento de una red (SNS) emergen de la socialización, cuando los grupos de personas empathize y descubren semejanzas entre sí mismos. La participación no definen a estas comunidades por el lugar o la cuenta sino la gente y. Validamos un marco conceptual de cómo forma de comunidades y crecemos vía SNS de la investigación etnográfica de un grupo en línea que ha emergido de redes sociales de convergencia en gorjeo. Definimos capas de uso, los individuos de los papeles adoptan en estas comunidades emergentes, y sus estrategias para la coexistencia. Esto es sostenida por una exploración de cómo transición de los grupos de orígenes interés-conducidos a apoyar interacciones amistad-conducidas

Complexity in relational processing predicts changes in functional brain network dynamics

The ability to link variables is critical to many high-order cognitive functions, including reasoning. It has been proposed that limits in relating variables depend critically on relational complexity, defined formally as the number of variables to be related in solving a problem. In humans, the prefrontal cortex is known to be important for reasoning, but recent studies have suggested that such processes are likely to involve widespread functional brain networks. To test this hypothesis, we used functional magnetic resonance imaging and a classic measure of deductive reasoning to examine changes in brain networks as a function of relational complexity. As expected, behavioral performance declined as the number of variables to be related increased. Likewise, increments in relational complexity were associated with proportional enhancements in brain activity and task-based connectivity within and between 2 cognitive control networks: A cingulo-opercular network for maintaining task set, and a fronto-parietal network for implementing trial-by-trial control. Changes in effective connectivity as a function of increased relational complexity suggested a key role for the left dorsolateral prefrontal cortex in integrating and implementing task set in a trial-by-trial manner. Our findings show that limits in relational processing are manifested in the brain as complexity-dependent modulations of large-scale networks