title: Proposed mechanism for learning and memory erasure in a white-noise-driven sleeping cortex

authors: Steyn-Ross, Moira L.

subjects: REM

abstract: Understanding the structure and purpose of sleep remains one of the grand challenges of neurobiology. Here we use a mean-field linearized theory of the sleeping cortex to derive statistics for synaptic learning and memory erasure. The growth in correlated low-frequency high-amplitude voltage fluctuations during slow-wave sleep (SWS) is characterized by a probability density function that becomes broader and shallower as the transition into rapid-eye-movement (REM) sleep is approached. At transition, the Shannon information entropy of the fluctuations is maximized. If we assume Hebbian-learning rules apply to the cortex, then its correlated response to white-noise stimulation during SWS provides a natural mechanism for a synaptic weight change that will tend to shut down reverberant neural activity. In contrast, during REM sleep the weights will evolve in a direction that encourages excitatory activity. These entropy and weight-change predictions lead us to identify the final portion of deep SWS that occurs immediately prior to transition into REM sleep as a time of enhanced erasure of labile memory. We draw a link between the sleeping cortex and Landauer's dissipation theorem for irreversible computing [R. Landauer, IBM J. Res. Devel. 5, 183 (1961)], arguing that because information erasure is an irreversible computation, there is an inherent entropy cost as the cortex transits from SWS into REM sleep.

text: Proposed mechanism for learning and memory erasure in a white-noise-driven sleeping cortex Understanding the structure and purpose of sleep remains one of the grand challenges of neurobiology. Here we use a mean-field linearized theory of the sleeping cortex to derive statistics for synaptic learning and memory erasure. The growth in correlated low-frequency high-amplitude voltage fluctuations during slow-wave sleep (SWS) is characterized by a probability density function that becomes broader and shallower as the transition into rapid-eye-movement (REM) sleep is approached. At transition, the Shannon information entropy of the fluctuations is maximized. If we assume Hebbian-learning rules apply to the cortex, then its correlated response to white-noise stimulation during SWS provides a natural mechanism for a synaptic weight change that will tend to shut down reverberant neural activity. In contrast, during REM sleep the weights will evolve in a direction that encourages excitatory activity. These entropy and weight-change predictions lead us to identify the final portion of deep SWS that occurs immediately prior to transition into REM sleep as a time of enhanced erasure of labile memory. We draw a link between the sleeping cortex and Landauer's dissipation theorem for irreversible computing [R. Landauer, IBM J. Res. Devel. 5, 183 (1961)], arguing that because information erasure is an irreversible computation, there is an inherent entropy cost as the cortex transits from SWS into REM sleep.

year: 2005

title: Review: Marine natural products

authors: Blunt, John W.

subjects: marine natural products

abstract: This review covers the literature published in 2003 for marine natural products, with 619 citations (413 for the period January to December 2003) referring to compounds isolated from marine microorganisms and phytoplankton, green algae, brown algae, red algae, sponges, coelenterates, bryozoans, molluscs, tunicates and echinoderms. The emphasis is on new compounds (656 for 2003), together with their relevant biological activities, source organisms and country of origin. Biosynthetic studies or syntheses that lead to the revision of structures or stereochemistries have been included (78), including any ﬁrst total syntheses of a marine natural product.

text: Review: Marine natural products This review covers the literature published in 2003 for marine natural products, with 619 citations (413 for the period January to December 2003) referring to compounds isolated from marine microorganisms and phytoplankton, green algae, brown algae, red algae, sponges, coelenterates, bryozoans, molluscs, tunicates and echinoderms. The emphasis is on new compounds (656 for 2003), together with their relevant biological activities, source organisms and country of origin. Biosynthetic studies or syntheses that lead to the revision of structures or stereochemistries have been included (78), including any ﬁrst total syntheses of a marine natural product.

year: 2005

title: Linking land, river and moana: Collaborative research between Te Whakatōhea and Lincoln University within the coastal rohe

authors: Morris, Richard

abstract: In the eastern Bay of Plenty, where the land yields to the Pacific and the Waioeka and Ōtara Rivers meet Te Moana aToi (the Bay of Plenty), a research partnership is flourishing between Te Whakatōhea iwi, Lincoln University Centre of Excellence Designing Future Productive Landscape (DFPL), and Waikato University. This collaboration has grown over several years into a suite of multidisciplinary research projects focused on agricultural systems design, urban planning, and climate resilience. While distinct in their objectives, these research threads are united by a deeper, unavoidable theme: the interconnection between whenua (land), awa (river), and moana (sea). For Te Whakatōhea, these are not separate domains but a continuous space of identity, sustenance, and economy, an ethos that sits well with DFPL.

text: Linking land, river and moana: Collaborative research between Te Whakatōhea and Lincoln University within the coastal rohe In the eastern Bay of Plenty, where the land yields to the Pacific and the Waioeka and Ōtara Rivers meet Te Moana aToi (the Bay of Plenty), a research partnership is flourishing between Te Whakatōhea iwi, Lincoln University Centre of Excellence Designing Future Productive Landscape (DFPL), and Waikato University. This collaboration has grown over several years into a suite of multidisciplinary research projects focused on agricultural systems design, urban planning, and climate resilience. While distinct in their objectives, these research threads are united by a deeper, unavoidable theme: the interconnection between whenua (land), awa (river), and moana (sea). For Te Whakatōhea, these are not separate domains but a continuous space of identity, sustenance, and economy, an ethos that sits well with DFPL.

year: 2025-11