title: EEG slow-wave coherence changes in propofol-induced general anesthesia: experiment and theory.

authors: Wang, Kaier

subjects: Turing–Hopf instabilities

abstract: The electroencephalogram (EEG) patterns recorded during general anesthetic-induced coma are closely similar to those seen during slow-wave sleep, the deepest stage of natural sleep; both states show patterns dominated by large amplitude slow waves. Slow oscillations are believed to be important for memory consolidation during natural sleep. Tracking the emergence of slow-wave oscillations during transition to unconsciousness may help us to identify drug-induced alterations of the underlying brain state, and provide insight into the mechanisms of general anesthesia. Although cellular-based mechanisms have been proposed, the origin of the slow oscillation has not yet been unambiguously established. A recent theoretical study by Steyn-Ross et al. (2013) proposes that the slow oscillation is a network, rather than cellular phenomenon. Modeling anesthesia as a moderate reduction in gap-junction interneuronal coupling, they predict an unconscious state signposted by emergent low-frequency oscillations with chaotic dynamics in space and time. They suggest that anesthetic slow-waves arise from a competitive interaction between symmetry-breaking instabilities in space (Turing) and time (Hopf), modulated by gap-junction coupling strength. A significant prediction of their model is that EEG phase coherence will decrease as the cortex transits from Turing-Hopf balance (wake) to Hopf-dominated chaotic slow-waves (unconsciousness). Here, we investigate changes in phase coherence during induction of general anesthesia. After examining 128-channel EEG traces recorded from five volunteers undergoing propofol anesthesia, we report a significant drop in sub-delta band (0.05-1.5 Hz) slow-wave coherence between frontal, occipital, and frontal-occipital electrode pairs, with the most pronounced wake-vs.-unconscious coherence changes occurring at the frontal cortex.

text: EEG slow-wave coherence changes in propofol-induced general anesthesia: experiment and theory. The electroencephalogram (EEG) patterns recorded during general anesthetic-induced coma are closely similar to those seen during slow-wave sleep, the deepest stage of natural sleep; both states show patterns dominated by large amplitude slow waves. Slow oscillations are believed to be important for memory consolidation during natural sleep. Tracking the emergence of slow-wave oscillations during transition to unconsciousness may help us to identify drug-induced alterations of the underlying brain state, and provide insight into the mechanisms of general anesthesia. Although cellular-based mechanisms have been proposed, the origin of the slow oscillation has not yet been unambiguously established. A recent theoretical study by Steyn-Ross et al. (2013) proposes that the slow oscillation is a network, rather than cellular phenomenon. Modeling anesthesia as a moderate reduction in gap-junction interneuronal coupling, they predict an unconscious state signposted by emergent low-frequency oscillations with chaotic dynamics in space and time. They suggest that anesthetic slow-waves arise from a competitive interaction between symmetry-breaking instabilities in space (Turing) and time (Hopf), modulated by gap-junction coupling strength. A significant prediction of their model is that EEG phase coherence will decrease as the cortex transits from Turing-Hopf balance (wake) to Hopf-dominated chaotic slow-waves (unconsciousness). Here, we investigate changes in phase coherence during induction of general anesthesia. After examining 128-channel EEG traces recorded from five volunteers undergoing propofol anesthesia, we report a significant drop in sub-delta band (0.05-1.5 Hz) slow-wave coherence between frontal, occipital, and frontal-occipital electrode pairs, with the most pronounced wake-vs.-unconscious coherence changes occurring at the frontal cortex.

year: 2014

title: AFOMP Policy Statement No. 3: recommendations for the education and training of medical physicists in AFOMP countries

authors: Round, W. Howell

subjects: education

abstract: AFOMP recognizes that clinical medical physicists should demonstrate that they are competent to practice their profession by obtaining appropriate education, training and supervised experience in the specialties of medical physics in which they practice, as well as having a basic knowledge of other specialties. To help its member countries to achieve this, AFOMP has developed this policy to provide guidance when developing medical physicist education and training programs. The policy is compatible with the standards being promoted by the International Organization for Medical Physics and the International Medical Physics Certification Board.

text: AFOMP Policy Statement No. 3: recommendations for the education and training of medical physicists in AFOMP countries AFOMP recognizes that clinical medical physicists should demonstrate that they are competent to practice their profession by obtaining appropriate education, training and supervised experience in the specialties of medical physics in which they practice, as well as having a basic knowledge of other specialties. To help its member countries to achieve this, AFOMP has developed this policy to provide guidance when developing medical physicist education and training programs. The policy is compatible with the standards being promoted by the International Organization for Medical Physics and the International Medical Physics Certification Board.

year: 2011

title: Experiences from the past inform the journey ahead: ‘a way of being’ - culturally responsive and relational professional learning and development.

authors: Murray, Tracy Olive

subjects: Culturally responsive and relational angragogy

abstract: This thesis begins by contextualising the current reality for many Māori learners in Aotearoa New Zealand.  By reviewing the literature around the role of the provider in professional learning and development (PLD) in Aotearoa New Zealand, this thesis seeks to explain a new way of working that has not been well documented before.  Provided is the rationale for the methodology undertaken in the research to ensure the relationship with the participants remained at the heart of the process.  This thesis contends that applying culturally responsive and relational pedagogy across all levels of schooling is a unique way of being that requires deep critical self-reflection and conscious ongoing change in practice.  Learning what to stop doing and what to do differently is part of an ongoing cycle of inquiry that educational leaders at any level must engage in, to implement change in schools for Māori learners.

text: Experiences from the past inform the journey ahead: ‘a way of being’ - culturally responsive and relational professional learning and development. This thesis begins by contextualising the current reality for many Māori learners in Aotearoa New Zealand.  By reviewing the literature around the role of the provider in professional learning and development (PLD) in Aotearoa New Zealand, this thesis seeks to explain a new way of working that has not been well documented before.  Provided is the rationale for the methodology undertaken in the research to ensure the relationship with the participants remained at the heart of the process.  This thesis contends that applying culturally responsive and relational pedagogy across all levels of schooling is a unique way of being that requires deep critical self-reflection and conscious ongoing change in practice.  Learning what to stop doing and what to do differently is part of an ongoing cycle of inquiry that educational leaders at any level must engage in, to implement change in schools for Māori learners.

year: 2018