title: Cortical patterns and gamma genesis are modulated by reversal potentials and gap-junction diffusion

authors: Steyn-Ross, Moira L.

subjects: gap junctions

abstract: In this chapter we describe a continuum model for the cortex that includes both axon-to-dendrite chemical synapses and direct neuron-to-neuron gap-junction diffusive synapses. The effectiveness of chemical synapses is determined by the voltage of the receiving dendrite V relative to its Nernst reversal potential Vrev. Here we explore two alternative strategies for incorporating dendritic reversal potentials, and uncover surprising differences in their stability properties and model dynamics. In the “slow-soma” variant, the (Vrev - V) weighting is applied after the input flux has been integrated at the dendrite, while for “fast-soma”, the weighting is applied directly to the input flux, prior to dendritic integration. For the slow-soma case, we find that–-provided the inhibitory diffusion (via gap-junctions) is sufficiently strong–-the cortex generates stationary Turing patterns of cortical activity. In contrast, the fast-soma destabilizes in favor of standing-wave spatial structures that oscillate at low-gamma frequency (  30-Hz); these spatial patterns broaden and weaken as diffusive coupling increases, and disappear altogether at moderate levels of diffusion. We speculate that the slow- and fast-soma models might correspond respectively to the idling and active modes of the cortex, with slow-soma patterns providing the default background state, and emergence of gamma oscillations in the fast-soma case signaling the transition into the cognitive state.

text: Cortical patterns and gamma genesis are modulated by reversal potentials and gap-junction diffusion In this chapter we describe a continuum model for the cortex that includes both axon-to-dendrite chemical synapses and direct neuron-to-neuron gap-junction diffusive synapses. The effectiveness of chemical synapses is determined by the voltage of the receiving dendrite V relative to its Nernst reversal potential Vrev. Here we explore two alternative strategies for incorporating dendritic reversal potentials, and uncover surprising differences in their stability properties and model dynamics. In the “slow-soma” variant, the (Vrev - V) weighting is applied after the input flux has been integrated at the dendrite, while for “fast-soma”, the weighting is applied directly to the input flux, prior to dendritic integration. For the slow-soma case, we find that–-provided the inhibitory diffusion (via gap-junctions) is sufficiently strong–-the cortex generates stationary Turing patterns of cortical activity. In contrast, the fast-soma destabilizes in favor of standing-wave spatial structures that oscillate at low-gamma frequency (  30-Hz); these spatial patterns broaden and weaken as diffusive coupling increases, and disappear altogether at moderate levels of diffusion. We speculate that the slow- and fast-soma models might correspond respectively to the idling and active modes of the cortex, with slow-soma patterns providing the default background state, and emergence of gamma oscillations in the fast-soma case signaling the transition into the cognitive state.

year: 2010

title: Disease surveillance and patient care in remote regions: an exploratory study of collaboration among healthcare professionals in Amazonia

authors: Luz, Saturnino

subjects: computer supported cooperative work

abstract: The development and deployment of information technology, particularly mobile tools, to support collaboration between different groups of healthcare professionals has been viewed as a promising way to improve disease surveillance and patient care in remote regions. The effects of global climate change combined with rapid changes to land cover and use in Amazonia are believed to be contributing to the spread of vector-borne emerging and neglected diseases. This makes empowering and providing support for local healthcare providers all the more important. We investigate the use of information technology in this context to support professionals whose activities range from diagnosing diseases and monitoring their spread to developing policies to deal with outbreaks. An analysis of stakeholders, their roles and requirements, is presented which encompasses results of fieldwork and of a process of design and prototyping complemented by questionnaires and targeted interviews. Findings are analysed with respect to the tasks of diagnosis, training of local healthcare professionals, and gathering, sharing and visualisation of data for purposes of epidemiological research and disease surveillance. Methodological issues regarding the elicitation of cooperation and collaboration requirements are discussed and implications are drawn with respect to the use of technology in tackling emerging and neglected diseases.

text: Disease surveillance and patient care in remote regions: an exploratory study of collaboration among healthcare professionals in Amazonia The development and deployment of information technology, particularly mobile tools, to support collaboration between different groups of healthcare professionals has been viewed as a promising way to improve disease surveillance and patient care in remote regions. The effects of global climate change combined with rapid changes to land cover and use in Amazonia are believed to be contributing to the spread of vector-borne emerging and neglected diseases. This makes empowering and providing support for local healthcare providers all the more important. We investigate the use of information technology in this context to support professionals whose activities range from diagnosing diseases and monitoring their spread to developing policies to deal with outbreaks. An analysis of stakeholders, their roles and requirements, is presented which encompasses results of fieldwork and of a process of design and prototyping complemented by questionnaires and targeted interviews. Findings are analysed with respect to the tasks of diagnosis, training of local healthcare professionals, and gathering, sharing and visualisation of data for purposes of epidemiological research and disease surveillance. Methodological issues regarding the elicitation of cooperation and collaboration requirements are discussed and implications are drawn with respect to the use of technology in tackling emerging and neglected diseases.

year: 2015

title: Mates at the school gates:Investigating peer relationships among rangatahi Māori

authors: Knowles, Anthea Heather

subjects: school attendance

abstract: As a teacher, I have found that while some rangatahi feel connected to school, many others do not. In an attempt to reduce the gap between Māori and non-Māori educational achievement, there have been significant nationwide initiatives implemented into schools across New Zealand. These programmes have been centred mostly around improving school engagement. Despite these efforts, school attendance rates among Māori continue to decline. This thesis explores the role of peer relationships among rangatahi Māori, including how these relationships may influence various domains of engagement at school, such as participation, belonging and orientation to learning. 

This research involves focus group interviews with six rangatahi Māori aged 17-18, and in Years 12 and 13 in a small-town New Zealand High School. The wāhine Māori who contributed to the study, had been identified by the school as successfully engaged through regular attendance and participation of school activites. The findings from this study identify some critical aspects to building strong peer relationships, including: having a social space to gather, practicing manaakitanga, recognising equity, maintaining connection with each other, and welcoming humour. The rangatahi in this study value their peers and social relationships and they freely access these resources as needed. In doing so they are able to collectively critique experiences of marginalisation and acquire a collective source of resilience. The participants in this study then draw on this collective resilience during challenging situations.

text: Mates at the school gates:Investigating peer relationships among rangatahi Māori As a teacher, I have found that while some rangatahi feel connected to school, many others do not. In an attempt to reduce the gap between Māori and non-Māori educational achievement, there have been significant nationwide initiatives implemented into schools across New Zealand. These programmes have been centred mostly around improving school engagement. Despite these efforts, school attendance rates among Māori continue to decline. This thesis explores the role of peer relationships among rangatahi Māori, including how these relationships may influence various domains of engagement at school, such as participation, belonging and orientation to learning. 

This research involves focus group interviews with six rangatahi Māori aged 17-18, and in Years 12 and 13 in a small-town New Zealand High School. The wāhine Māori who contributed to the study, had been identified by the school as successfully engaged through regular attendance and participation of school activites. The findings from this study identify some critical aspects to building strong peer relationships, including: having a social space to gather, practicing manaakitanga, recognising equity, maintaining connection with each other, and welcoming humour. The rangatahi in this study value their peers and social relationships and they freely access these resources as needed. In doing so they are able to collectively critique experiences of marginalisation and acquire a collective source of resilience. The participants in this study then draw on this collective resilience during challenging situations.

year: 2019