Nucleus reuniens transiently synchronizes memory networks at beta frequencies.

Episodic memory-based decision-making requires top-down medial prefrontal cortex and hippocampal interactions. This integrated prefrontal-hippocampal memory state is thought to be organized by synchronized network oscillations and mediated by connectivity with the thalamic nucleus reuniens (RE). Whether and how the RE synchronizes prefrontal-hippocampal networks in memory, however, remains unknown. Here, we recorded local field potentials from the prefrontal-RE-hippocampal network while rats engaged in a nonspatial sequence memory task, thereby isolating memory-related activity from running-related oscillations. We found that synchronous prefrontal-hippocampal beta bursts (15-30 Hz) dominated during memory trials, whereas synchronous theta activity (6-12 Hz) dominated during non-memory-related running. Moreover, RE beta activity appeared first, followed by prefrontal and hippocampal synchronized beta, suggesting that prefrontal-hippocampal beta could be driven by the RE. To test whether the RE is capable of driving prefrontal-hippocampal beta synchrony, we used an optogenetic approach (retroAAV-ChR2). RE activation induced prefrontal-hippocampal beta coherence and reduced theta coherence, matching the observed memory-driven network state in the sequence task. These findings are the first to demonstrate that the RE contributes to memory by driving transient synchronized beta in the prefrontal-hippocampal system, thereby facilitating interactions that underlie memory-based decision-making.

An Innovative Design for the Vaginal Speculum.

Introduction: The main objective of this study is to evaluate the effectiveness of a newly designed vaginal speculum, the Bouquet Speculum, in-vitro. The setting of this study was at Florida International University and involved four senior students in the Department of Biomedical Engineering. Methods: A phantom vaginal model was used to test three variables of the Bouquet Speculum (Visibility, Pressure and Gynecologic Tools tests). As this was bench-lab testing with simulated models, no human participants were involved in this study. Results: The results of this in-vitro study are as follows: The visibility test demonstrated statistically better visualization of the cervix and the cervical os (sampling area for pap tests) with the Bouquet Speculum over the existing 2-bladed speculum at all intrapelvic pressures; The pressure test demonstrated an equal radial distribution of force, without breakage, across the Bouquet Speculum; The gynecologic tools test demonstrated that the Bouquet Speculum is compatible with the existing speculum and standard gynecologic tools in terms of retrieving samples and accessing the cervical os and entire cervix during gynecologic procedures and screening. Conclusion: The gynecologic screening and procedural value of this innovative change in the design of the vaginal speculum could save hundreds of thousands of lives every year, provide a more comfortable exam for the patient, and result in a more efficient and user-friendly provider experience.