Propagation of sharp wave-ripple activity in the mouse hippocampal CA3 subfield in vitro.

Sharp wave-ripple complexes (SPW-Rs) are spontaneous oscillatory events that characterize hippocampal activity during resting periods and slow-wave sleep. SPW-Rs are related to memory consolidation - the process during which newly acquired memories are transformed into long-lasting memory traces. To test the involvement of SPW-Rs in this process, it is crucial to understand how SPW-Rs originate and propagate throughout the hippocampus. SPW-Rs can originate in CA3, and they typically spread from CA3 to CA1, but little is known about their formation within CA3. To investigate the generation and propagation of SPW-Rs in CA3, we recorded from mouse hippocampal slices using multi-electrode arrays and patch-clamp electrodes. We characterized extracellular and intracellular correlates of SPW-Rs and quantified their propagation along the pyramidal cell layer of CA3. We found that a hippocampal slice can be described by a speed and a direction of propagation of SPW-Rs. The preferred propagation direction was from CA3c (the subfield closer to the dentate gyrus) toward CA3a (the subfield at the boundary to CA2). In patch-clamp recordings from CA3 pyramidal neurons, propagation was estimated separately for excitatory and inhibitory currents associated with SPW-Rs. We found that propagation speed and direction of excitatory and inhibitory currents were correlated. The magnitude of the speed of propagation of SPW-Rs within CA3 was consistent with the speed of propagation of action potentials in axons of CA3 principal cells. KEY POINTS: Hippocampal sharp waves are considered important for memory consolidation; therefore, it is of interest to understand the mechanisms of their generation and propagation. Here, we used two different approaches to study the propagation of sharp waves in mouse CA3 in vitro: multi-electrode arrays and multiple single-cell recordings. We find a preferred direction of propagation of sharp waves from CA3c toward CA3a - both in the local field potential and in sharp wave-associated excitatory and inhibitory synaptic activity. The speed of sharp wave propagation is consistent with the speed of action potential propagation along the axons of CA3 pyramidal neurons. These new insights into the dynamics of sharp waves in the CA3 network will inform future experiments and theoretical models of sharp-wave generation mechanisms.

Factors in the Building of Effective Patient-Provider Relationships in the Context of Fibromyalgia.

OBJECTIVE: Fibromyalgia patients face particular challenges in building relationships with health care providers. In this study, we examine, from patients' perspectives, factors that influence the formation of effective patient-provider relationships. DESIGN: This research employed a qualitative approach to analyze data collected from a study that employed semistructured interviews. METHODS: Multiple methods were used to recruit 23 fibromyalgia patients for interviews. Semistructured interviews were conducted to explore how participants' information behaviors, including their communication with and relationships to providers, changed over time. The interview data were analyzed using a qualitative analytic method based on interpretative phenomenological analysis and constructivist grounded theory. RESULTS: We identified three important factors that influenced the building of effective relationships: patients and providers' interactions involving information, identifying health care providers that fit patients' needs, and realizing shared responsibilities. With regard to information, we described three important themes: information gaps, providers as educators/facilitators, and collaborative information behavior. CONCLUSIONS: Understanding of the key elements of relationship development between patients and providers can be utilized in various ways to improve clinical care. First, the knowledge gained in this study can inform the design of patient education materials that assist patients to identify providers that fit their needs, prepare for consultations, and develop realistic expectations for providers. The findings of this study can also inform the design of resources and tools to enable clinicians to communicate and relate better with their patients.

Incorporating user feedback in the design of a genetics analysis tool: A two-part approach.

While general usability assessment models for websites have been developed for a wide variety of contexts, research literature on incorporating user feedback in the design of online scientific tools is lacking. In this article, we present an approach that we developed and illustrate how it was used to elicit user feedback of the AnalyzeMyVariant tool, which enables geneticists to use family pedigree data to calculate pathogenicity likelihood ratios for variants of unknown significance. We reviewed existing usability literature and developed a survey instrument emphasizing concepts of importance to online, data-driven, scientific tools. The items on the survey instrument were grouped in four categories: usability, quality, privacy and security, and satisfaction. We performed a two-part evaluation using the survey and a semi-structured interview protocol. The survey instrument was used to collect data about the use experience of AnalyzeMyVariant from 57 genetic experts and trainees who were recruited via email invitations. We also conducted semi-structured interviews with six genetics experts to explore work contexts in which users might use the tool and further delve into issues faced in tool use. Interviews were inductively coded and major themes identified using the constant comparative method. We found that the needs of genetics professionals vary for research- and clinically-focused work. These differences can inform the design of tools to serve their needs. The major contribution of this work is the description of a two-part method to elicit user feedback to inform the design of online, data-driven, scientific tools, which focuses on constructs of particular relevance to these tools such as usability, quality, privacy, security, and satisfaction. The survey instrument that we developed, coupled with contextual interviews, may serve as an example that can be used by others conducting usability studies of similar tools. In addition, our results emphasize the importance of considering contextual factors such as background knowledge, situational factors, and the intended application of results, in the usability evaluation of scientific software. It is our hope that this two-part approach might be adapted to assess the usability of other online scientific tools and facilitate the design of tools to meet the needs of their target audiences.

Regulation of Dendritic Spine Morphology in Hippocampal Neurons by Copine-6.

Dendritic spines compartmentalize information in the brain, and their morphological characteristics are thought to underly synaptic plasticity. Here we identify copine-6 as a novel modulator of dendritic spine morphology. We found that brain-derived neurotrophic factor (BDNF) - a molecule essential for long-term potentiation of synaptic strength - upregulated and recruited copine-6 to dendritic spines in hippocampal neurons. Overexpression of copine-6 increased mushroom spine number and decreased filopodia number, while copine-6 knockdown had the opposite effect and dramatically increased the number of filopodia, which lacked PSD95. Functionally, manipulation of post-synaptic copine-6 levels affected miniature excitatory post-synaptic current (mEPSC) kinetics and evoked synaptic vesicle recycling in contacting boutons, and post-synaptic knockdown of copine-6 reduced hippocampal LTP and increased LTD. Mechanistically, copine-6 promotes BDNF-TrkB signaling and recycling of activated TrkB receptors back to the plasma membrane surface, and is necessary for BDNF-induced increases in mushroom spines in hippocampal neurons. Thus copine-6 regulates BDNF-dependent changes in dendritic spine morphology to promote synaptic plasticity.

Understanding User Experience: Exploring Participants' Messages With a Web-Based Behavioral Health Intervention for Adolescents With Chronic Pain.

BACKGROUND: Delivery of behavioral health interventions on the internet offers many benefits, including accessibility, cost-effectiveness, convenience, and anonymity. In recent years, an increased number of internet interventions have been developed, targeting a range of conditions and behaviors, including depression, pain, anxiety, sleep disturbance, and eating disorders. Human support (coaching) is a common component of internet interventions that is intended to boost engagement; however, little is known about how participants interact with coaches and how this may relate to their experience with the intervention. By examining the data that participants produce during an intervention, we can characterize their interaction patterns and refine treatments to address different needs. OBJECTIVE: In this study, we employed text mining and visual analytics techniques to analyze messages exchanged between coaches and participants in an internet-delivered pain management intervention for adolescents with chronic pain and their parents. METHODS: We explored the main themes in coaches' and participants' messages using an automated textual analysis method, topic modeling. We then clustered participants' messages to identify subgroups of participants with similar engagement patterns. RESULTS: First, we performed topic modeling on coaches' messages. The themes in coaches' messages fell into 3 categories: Treatment Content, Administrative and Technical, and Rapport Building. Next, we employed topic modeling to identify topics from participants' message histories. Similar to the coaches' topics, these were subsumed under 3 high-level categories: Health Management and Treatment Content, Questions and Concerns, and Activities and Interests. Finally, the cluster analysis identified 4 clusters, each with a distinguishing characteristic: Assignment-Focused, Short Message Histories, Pain-Focused, and Activity-Focused. The name of each cluster exemplifies the main engagement patterns of that cluster. CONCLUSIONS: In this secondary data analysis, we demonstrated how automated text analysis techniques could be used to identify messages of interest, such as questions and concerns from users. In addition, we demonstrated how cluster analysis could be used to identify subgroups of individuals who share communication and engagement patterns, and in turn facilitate personalization of interventions for different subgroups of patients. This work makes 2 key methodological contributions. First, this study is innovative in its use of topic modeling to provide a rich characterization of the textual content produced by coaches and participants in an internet-delivered behavioral health intervention. Second, to our knowledge, this is the first example of the use of a visual analysis method to cluster participants and identify similar patterns of behavior based on intervention message content.

Subiculum as a generator of sharp wave-ripples in the rodent hippocampus.

Sharp wave-ripples (SWRs) represent synchronous discharges of hippocampal neurons and are believed to play a major role in memory consolidation. A large body of evidence suggests that SWRs are exclusively generated in the CA3-CA2 network. In contrast, here, we provide several lines of evidence showing that the subiculum can function as a secondary SWRs generator. SWRs with subicular origin propagate forward into the entorhinal cortex as well as backward into the hippocampus proper. Our findings suggest that the output structures of the hippocampus are not only passively facilitating the transfer of SWRs to the cortex, but they also can actively contribute to the genesis of SWRs. We hypothesize that SWRs with a subicular origin may be important for the consolidation of information conveyed to the hippocampus via the temporoammonic pathway.

Neuronal Autophagy Regulates Presynaptic Neurotransmission by Controlling the Axonal Endoplasmic Reticulum.

Neurons are known to rely on autophagy for removal of defective proteins or organelles to maintain synaptic neurotransmission and counteract neurodegeneration. In spite of its importance for neuronal health, the physiological substrates of neuronal autophagy in the absence of proteotoxic challenge have remained largely elusive. We use knockout mice conditionally lacking the essential autophagy protein ATG5 and quantitative proteomics to demonstrate that loss of neuronal autophagy causes selective accumulation of tubular endoplasmic reticulum (ER) in axons, resulting in increased excitatory neurotransmission and compromised postnatal viability in vivo. The gain in excitatory neurotransmission is shown to be a consequence of elevated calcium release from ER stores via ryanodine receptors accumulated in axons and at presynaptic sites. We propose a model where neuronal autophagy controls axonal ER calcium stores to regulate neurotransmission in healthy neurons and in the brain.

Species-specific differences in synaptic transmission and plasticity.

Synaptic transmission and plasticity in the hippocampus are integral factors in learning and memory. While there has been intense investigation of these critical mechanisms in the brain of rodents, we lack a broader understanding of the generality of these processes across species. We investigated one of the smallest animals with conserved hippocampal macroanatomy-the Etruscan shrew, and found that while synaptic properties and plasticity in CA1 Schaffer collateral synapses were similar to mice, CA3 mossy fiber synapses showed striking differences in synaptic plasticity between shrews and mice. Shrew mossy fibers have lower long term plasticity compared to mice. Short term plasticity and the expression of a key protein involved in it, synaptotagmin 7 were also markedly lower at the mossy fibers in shrews than in mice. We also observed similar lower expression of synaptotagmin 7 in the mossy fibers of bats that are evolutionarily closer to shrews than mice. Species specific differences in synaptic plasticity and the key molecules regulating it, highlight the evolutionary divergence of neuronal circuit functions.

Involvement of Mossy Cells in Sharp Wave-Ripple Activity In Vitro.

The role of mossy cells (MCs) of the hippocampal dentate area has long remained mysterious. Recent research has begun to unveil their significance in spatial computation of the hippocampus. Here, we used an in vitro model of sharp wave-ripple complexes (SWRs), which contribute to hippocampal memory formation, to investigate MC involvement in this fundamental population activity. We find that a significant fraction of MCs (∼47%) is recruited into the active neuronal network during SWRs in the CA3 area. Moreover, MCs receive pronounced, ripple-coherent, excitatory and inhibitory synaptic input. Finally, we find evidence for SWR-related synaptic activity in granule cells that is mediated by MCs. Given the widespread connectivity of MCs within and between hippocampi, our data suggest a role for MCs as a hub functionally coupling the CA3 and the DG during ripple-associated computations.