title: Gap junctions modulate seizures in a mean-field model of general anesthesia for the cortex

authors: Steyn-Ross, Moira L.

subjects: gap junctions

abstract: During slow-wave sleep, general anesthesia, and generalized seizures, there is an absence of consciousness. These states are characterized by low-frequency large-amplitude traveling waves in scalp electroencephalogram. Therefore the oscillatory state might be an indication of failure to form coherent neuronal assemblies necessary for consciousness. A generalized seizure event is a pathological brain state that is the clearest manifestation of waves of synchronized neuronal activity. Since gap junctions provide a direct electrical connection between adjoining neurons, thus enhancing synchronous behavior, reducing gap-junction conductance should suppress seizures; however there is no clear experimental evidence for this. Here we report theoretical predictions for a physiologically-based cortical model that describes the general anesthetic phase transition from consciousness to coma, and includes both chemical synaptic and direct electrotonic synapses. The model dynamics exhibits both Hopf (temporal) and Turing (spatial) instabilities; the Hopf instability corresponds to the slow ([≲8 Hz) oscillatory states similar to those seen in slow-wave sleep, general anesthesia, and seizures. We argue that a delicately balanced interplay between Hopf and Turing modes provides a canonical mechanism for the default non-cognitive rest state of the brain. We show that the Turing mode, set by gap-junction diffusion, is generally protective against entering oscillatory modes; and that weakening the Turing mode by reducing gap conduction can release an uncontrolled Hopf oscillation and hence an increased propensity for seizure and simultaneously an increased sensitivity to GABAergic anesthesia.

text: Gap junctions modulate seizures in a mean-field model of general anesthesia for the cortex During slow-wave sleep, general anesthesia, and generalized seizures, there is an absence of consciousness. These states are characterized by low-frequency large-amplitude traveling waves in scalp electroencephalogram. Therefore the oscillatory state might be an indication of failure to form coherent neuronal assemblies necessary for consciousness. A generalized seizure event is a pathological brain state that is the clearest manifestation of waves of synchronized neuronal activity. Since gap junctions provide a direct electrical connection between adjoining neurons, thus enhancing synchronous behavior, reducing gap-junction conductance should suppress seizures; however there is no clear experimental evidence for this. Here we report theoretical predictions for a physiologically-based cortical model that describes the general anesthetic phase transition from consciousness to coma, and includes both chemical synaptic and direct electrotonic synapses. The model dynamics exhibits both Hopf (temporal) and Turing (spatial) instabilities; the Hopf instability corresponds to the slow ([≲8 Hz) oscillatory states similar to those seen in slow-wave sleep, general anesthesia, and seizures. We argue that a delicately balanced interplay between Hopf and Turing modes provides a canonical mechanism for the default non-cognitive rest state of the brain. We show that the Turing mode, set by gap-junction diffusion, is generally protective against entering oscillatory modes; and that weakening the Turing mode by reducing gap conduction can release an uncontrolled Hopf oscillation and hence an increased propensity for seizure and simultaneously an increased sensitivity to GABAergic anesthesia.

year: 2012

title: Intersections between place-responsive outdoor education and environmental action: Transforming secondary students' ethic of care into action.

authors: Martindale, Joanne

subjects: environmental action

abstract: There has been growing concern expressed about the disconnection of people, and particularly young people, from nature. This detachment from the natural world is visible through media and movies with an increased reference to the urban, human-made environment since the 1950’s. Additionally, it is observable in our overuse of the Earth's resources and slow change to more sustainable behaviour. The cost of this disconnection from nature is on our physical and psychological well-being. It reduces appreciation and attachment to place. This study looks at connecting secondary students to their place through a place-responsive outdoor education journey and explores how the journey can influence their developing ethic of care for place. 

Place-responsive outdoor education is one way to potentially connect and ‘re-wild’ our school students to their place and nature. Through this, they may develop an ethic of care. There is then an assumption that by developing an ethic of care and responding to place, people will take action to look after or improve their place. However, little research has been conducted to date to show that there is a link between attachment to place and pro-environmental behaviour or taking action. The second part of this research explored how any potential ethic of care developed from the place-responsive outdoor education journey could be transformed into motivation for students to act for place, by adapting the place-responsive outdoor education journey to incorporate environmental advocacy sessions using Birdsall's (2010) model for learning about environmental action.

This research uses a phenomenography approach to study the experiences of a group of secondary school students engaging in a place-responsive outdoor education journey and their responses to the journey. Twelve students came on the journey and six of these participated in the study. Data were gathered using photo-elicitation interviews based on photographs the students took during the place-responsive outdoor education journey. The students then attended a series of environmental advocacy sessions based on the journey to help them reflect and consider what response they might make to their experiences. A second interview was then held with each student after these sessions to explore their perceptions of an ethic of care leading to action. Data in the form of interview transcripts and observational notes were analysed and thematically organised. 

The first part of the study highlights the significance of a slow pedagogy to the place-responsive outdoor journey and the enjoyment by the students. Contextual factors like the weather had an impact on the students.  The journey also emphasised the importance of community and social interaction for the students. At the end of the place-responsive outdoor education journey, the students expressed a sense of accomplishment and a deeper connection to the city, realising it was more than just shopping malls.

The students indicated great enthusiasm and motivation to take action as the environmental advocacy sessions began. The students decided to use a voting system to decide on the final action to take, which lead to some students disengaging at this point as they may not have seen the relevance to them of the specific action chosen. For many of the students, other priorities and pressures made them feel too busy to have the time to take action. The findings indicate that students who have had repeat visits to place have a stronger connection to it and suggest this is a predictor of them continuing to taking action or display pro-environmental behaviour in response to their experiences.

text: Intersections between place-responsive outdoor education and environmental action: Transforming secondary students' ethic of care into action. There has been growing concern expressed about the disconnection of people, and particularly young people, from nature. This detachment from the natural world is visible through media and movies with an increased reference to the urban, human-made environment since the 1950’s. Additionally, it is observable in our overuse of the Earth's resources and slow change to more sustainable behaviour. The cost of this disconnection from nature is on our physical and psychological well-being. It reduces appreciation and attachment to place. This study looks at connecting secondary students to their place through a place-responsive outdoor education journey and explores how the journey can influence their developing ethic of care for place. 

Place-responsive outdoor education is one way to potentially connect and ‘re-wild’ our school students to their place and nature. Through this, they may develop an ethic of care. There is then an assumption that by developing an ethic of care and responding to place, people will take action to look after or improve their place. However, little research has been conducted to date to show that there is a link between attachment to place and pro-environmental behaviour or taking action. The second part of this research explored how any potential ethic of care developed from the place-responsive outdoor education journey could be transformed into motivation for students to act for place, by adapting the place-responsive outdoor education journey to incorporate environmental advocacy sessions using Birdsall's (2010) model for learning about environmental action.

This research uses a phenomenography approach to study the experiences of a group of secondary school students engaging in a place-responsive outdoor education journey and their responses to the journey. Twelve students came on the journey and six of these participated in the study. Data were gathered using photo-elicitation interviews based on photographs the students took during the place-responsive outdoor education journey. The students then attended a series of environmental advocacy sessions based on the journey to help them reflect and consider what response they might make to their experiences. A second interview was then held with each student after these sessions to explore their perceptions of an ethic of care leading to action. Data in the form of interview transcripts and observational notes were analysed and thematically organised. 

The first part of the study highlights the significance of a slow pedagogy to the place-responsive outdoor journey and the enjoyment by the students. Contextual factors like the weather had an impact on the students.  The journey also emphasised the importance of community and social interaction for the students. At the end of the place-responsive outdoor education journey, the students expressed a sense of accomplishment and a deeper connection to the city, realising it was more than just shopping malls.

The students indicated great enthusiasm and motivation to take action as the environmental advocacy sessions began. The students decided to use a voting system to decide on the final action to take, which lead to some students disengaging at this point as they may not have seen the relevance to them of the specific action chosen. For many of the students, other priorities and pressures made them feel too busy to have the time to take action. The findings indicate that students who have had repeat visits to place have a stronger connection to it and suggest this is a predictor of them continuing to taking action or display pro-environmental behaviour in response to their experiences.

year: 2017

title: A study of iwi communication between Te Tau Ihu iwi and intergenerational diasporic whānau

authors: Wright, Karamea Moana

subjects: diaspora

abstract: This study looks at the online communication methods used between Te Tau Ihu iwi and intergenerational uri who live in the diaspora. Preferences and perceptions of methods of communication utilized by both iwi, and tāngata who live in the overseas diaspora were explored. Most important are the implications for uri living away from Aotearoa, and their desire to remain connected to iwi in New Zealand. This is a mixed methods study, comprising of a survey of fifty-eight emigrant respondents living abroad, and interviews with one member of the first, second, and third generations of emigrants to the United States, with affiliation to at least one of the eight tribes who claim tāngata whenua status of Te Tau Ihu.

The implications of the findings from the study provide both iwi and tāngata the opportunity to create a synergistic relationship of communicating. Assisting iwi to develop and implement a strategy for relevant communication, and iwi members engaging in a dialogue with iwi about relevance of communication is critical in strengthening ties between iwi and future generations regardless of location. “He aha te mea nui, he tangata, he tangata.”

text: A study of iwi communication between Te Tau Ihu iwi and intergenerational diasporic whānau This study looks at the online communication methods used between Te Tau Ihu iwi and intergenerational uri who live in the diaspora. Preferences and perceptions of methods of communication utilized by both iwi, and tāngata who live in the overseas diaspora were explored. Most important are the implications for uri living away from Aotearoa, and their desire to remain connected to iwi in New Zealand. This is a mixed methods study, comprising of a survey of fifty-eight emigrant respondents living abroad, and interviews with one member of the first, second, and third generations of emigrants to the United States, with affiliation to at least one of the eight tribes who claim tāngata whenua status of Te Tau Ihu.

The implications of the findings from the study provide both iwi and tāngata the opportunity to create a synergistic relationship of communicating. Assisting iwi to develop and implement a strategy for relevant communication, and iwi members engaging in a dialogue with iwi about relevance of communication is critical in strengthening ties between iwi and future generations regardless of location. “He aha te mea nui, he tangata, he tangata.”

year: 2019