A metabolic function of the hippocampal sharp wave-ripple.

The hippocampus has previously been implicated in both cognitive and endocrine functions1-15. We simultaneously measured electrophysiological activity from the hippocampus and interstitial glucose concentrations in the body of freely behaving rats to identify an activity pattern that may link these disparate functions of the hippocampus. Here we report that clusters of sharp wave-ripples recorded from the hippocampus reliably predicted a decrease in peripheral glucose concentrations within about 10 min. This correlation was not dependent on circadian, ultradian or meal-triggered fluctuations, could be mimicked with optogenetically induced ripples in the hippocampus (but not in the parietal cortex) and was attenuated to chance levels by pharmacogenetically suppressing activity of the lateral septum, which is the major conduit between the hippocampus and the hypothalamus. Our findings demonstrate that a function of the sharp wave-ripple is to modulate peripheral glucose homeostasis, and offer a mechanism for the link between sleep disruption and blood glucose dysregulation in type 2 diabetes16-18.

Investigating Egocentric Tuning in Hippocampal CA1 Neurons.

Navigation requires integrating sensory information with a stable schema to create a dynamic map of an animal's position using egocentric and allocentric coordinate systems. In the hippocampus, place cells encode allocentric space, but their firing rates may also exhibit directional tuning within egocentric or allocentric reference frames. We compared experimental and simulated data to assess the prevalence of tuning to egocentric bearing (EB) among hippocampal cells in rats foraging in an open field. Using established procedures, we confirmed egocentric modulation of place cell activity in recorded data; however, simulated data revealed a high false-positive rate (FPR). When we accounted for false positives by comparing with shuffled data that retain correlations between the animal's direction and position, only a very low number of hippocampal neurons appeared modulated by EB. Our study highlights biases affecting FPRs and provides insights into the challenges of identifying egocentric modulation in hippocampal neurons.

Correction: Seeing the "Big" Picture: Big Data Methods for Exploring Relationships Between Usage, Language, and Outcome in Internet Intervention Data.

[This corrects the article DOI: 10.2196/jmir.5725.].

Seeing the "Big" Picture: Big Data Methods for Exploring Relationships Between Usage, Language, and Outcome in Internet Intervention Data.

BACKGROUND: Assessing the efficacy of Internet interventions that are already in the market introduces both challenges and opportunities. While vast, often unprecedented amounts of data may be available (hundreds of thousands, and sometimes millions of participants with high dimensions of assessed variables), the data are observational in nature, are partly unstructured (eg, free text, images, sensor data), do not include a natural control group to be used for comparison, and typically exhibit high attrition rates. New approaches are therefore needed to use these existing data and derive new insights that can augment traditional smaller-group randomized controlled trials. OBJECTIVE: Our objective was to demonstrate how emerging big data approaches can help explore questions about the effectiveness and process of an Internet well-being intervention. METHODS: We drew data from the user base of a well-being website and app called Happify. To explore effectiveness, multilevel models focusing on within-person variation explored whether greater usage predicted higher well-being in a sample of 152,747 users. In addition, to explore the underlying processes that accompany improvement, we analyzed language for 10,818 users who had a sufficient volume of free-text response and timespan of platform usage. A topic model constructed from this free text provided language-based correlates of individual user improvement in outcome measures, providing insights into the beneficial underlying processes experienced by users. RESULTS: On a measure of positive emotion, the average user improved 1.38 points per week (SE 0.01, t122,455=113.60, P<.001, 95% CI 1.36-1.41), about an 11% increase over 8 weeks. Within a given individual user, more usage predicted more positive emotion and less usage predicted less positive emotion (estimate 0.09, SE 0.01, t6047=9.15, P=.001, 95% CI .07-.12). This estimate predicted that a given user would report positive emotion 1.26 points (or 1.26%) higher after a 2-week period when they used Happify daily than during a week when they didn't use it at all. Among highly engaged users, 200 automatically clustered topics showed a significant (corrected P<.001) effect on change in well-being over time, illustrating which topics may be more beneficial than others when engaging with the interventions. In particular, topics that are related to addressing negative thoughts and feelings were correlated with improvement over time. CONCLUSIONS: Using observational analyses on naturalistic big data, we can explore the relationship between usage and well-being among people using an Internet well-being intervention and provide new insights into the underlying mechanisms that accompany it. By leveraging big data to power these new types of analyses, we can explore the workings of an intervention from new angles, and harness the insights that surface to feed back into the intervention and improve it further in the future.

Just between us: Exclusive communications in online social networks.

Social media websites such as Facebook are used for relationship development and maintenance often through self-disclosure and sharing of personal information. However, not all forms of social media communication may be equally suitable for this task. This paper explores users' norms about the appropriateness of using private vs. public Facebook messages to communicate different kinds of personal information, and the effectiveness of these types of communication in building relationships. Study 1, a survey, revealed that users endorse conflicting expectations about preferences for receiving information publicly or privately. Study 2, a field experiment testing the effects of private versus public Facebook communications on actual relationship development using participants' own Facebook pages, suggested that private messages lead to greater closeness.

When to use your head and when to use your heart: the differential value of perspective-taking versus empathy in competitive interactions.

Four studies explored whether perspective-taking and empathy would be differentially effective in mixed-motive competitions depending on whether the critical skills for success were more cognitively or emotionally based. Study 1 demonstrated that individual differences in perspective-taking, but not empathy, predicted increased distributive and integrative performance in a multiple-round war game that required a clear understanding of an opponent's strategic intentions. Conversely, both measures and manipulations of empathy proved more advantageous than perspective-taking in a relationship-based coalition game that required identifying the strength of interpersonal connections (Studies 2-3). Study 4 established a key process: perspective-takers were more accurate in cognitive understanding of others, whereas empathy produced stronger accuracy in emotional understanding. Perspective-taking and empathy were each useful but in different types of competitive, mixed-motive situations-their success depended on the task-competency match. These results demonstrate when to use your head versus your heart to achieve the best outcomes for oneself.