Synthesizing realistic neural population activity patterns using generative adversarial networks

The ability to synthesize realistic patterns of neural activity is crucial for studying neural information processing. Here we used the Generative Adversarial Networks (GANs) framework to simulate the concerted activity of a population of neurons. We adapted the Wasserstein-GAN variant to facilitate the generation of unconstrained neural population activity patterns while still benefiting from parameter sharing in the temporal domain. We demonstrate that our proposed GAN, which we termed Spike-GAN, generates spike trains that match accurately the first- and second-order statistics of datasets of tens of neurons and also approximates well their higher-order statistics. We applied Spike-GAN to a real dataset recorded from salamander retina and showed that it performs as well as state-of-the-art approaches based on the maximum entropy and the dichotomized Gaussian frameworks. Importantly, Spike-GAN does not require to specify a priori the statistics to be matched by the model, and so constitutes a more flexible method than these alternative approaches. Finally, we show how to exploit a trained Spike-GAN to construct’importance maps’ to detect the most relevant statistical structures present in a spike train. Spike-GAN provides a powerful, easy-to-use technique for generating realistic spiking neural activity and for describing the most relevant features of the large-scale neural population recordings studied in modern systems neuroscience

Oral History Conversation With BH Kim and Kaison Tanabe (Impact Without Borders)

This is an oral history Interview that was conducted on March 28th, 2017 discussing entrepreneurship in the San Diego start-up community

Kinetics and cellular site of glycolipid loading control

CD1d-restricted natural killer T cells (NKT cells) possess a wide range of effector and regulatory activities that are related to their ability to secrete both T helper 1 (Th1) cell- and Th2 cell-type cytokines. We analyzed presentation of NKT cell activating α galactosylceramide (αGalCer) analogs that give predominantly Th2 cell-type cytokine responses to determine how ligand structure controls the outcome of NKT cell activation. Using a monoclonal antibody specific for αGalCer-CD1d complexes to visualize and quantitate glycolipid presentation, we found that Th2 cell-type cytokinebiasing ligands were characterized by rapid and direct loading of cell-surface CD1d proteins. Complexes formed by association of these Th2 cell-type cytokine-biasing αGalCer analogs with CD1d showed a distinctive exclusion from ganglioside-enriched, detergent-resistant plasma membrane microdomains of antigen-presenting cells. These findings help to explain how subtle alterations in glycolipid ligand structure can control the balance of proinflammatory and antiinflammatory activities of NKT cells

Combination of PCR targeting the VD2 of omp1 and reverse line blot analysis for typing of urogenital Chlamydia trachomatis serovars in cervical scrape specimens.

50% contained both serovars D and E. The nested VD2 PCR-RLB developed is a simple, fast, and specific method for the identification of individual urogenital C. trachomatis serovars previously detected by using plasmid PCR. Moreover, it is an appropriate method for studying multiple C. trachomatis infections and for use in large epidemiological studies

Evaluación biomecánica de la carga final de la tenodesis de bíceps

El interés en las diferentes técnicas de tenodesis artroscópica se ha incrementado en los últimos 10 años. Sin embargo, hay muy poca información publicada sobre sus propiedades biomecánicas y clínicas. El objetivo del presente estudio es analizar una de las propiedades biomecánicas de dos tipos diferentes de tenodesis artroscópicas de bíceps: PITT vs Sutura con Arpones. Material y métodos: 15 especímenes cadavéricos frescos congelados se aleatorizaron para ambas técnicas. Una vez realizada la cirugía, los húmeros con el tendón fijado al Ligamento Transverso, se montaron en una máquina de prueba de materiales en paralelo para llevar a cabo el protocolo de carga hasta el fallo a una velocidad de 1.25 mm/sec. Se obtuvo la carga final (N) y se consideró la variable principal. Se compararon ambas técnicas mediante el test paramétrico de la t de Student. Resultados: Ambos tipos de reparaciones mostraron cargas finales adecuadas: 175,46±40,4 N la sutura con arpones y 142,79±30,9 N la técnica PITT (p>0.05). Conclusión: La Sutura con Doble Arpón y PITT demostraron una resistencia satisfactoria inicial sin diferencias significativas entre ambos grupos. Ambas técnicas son útiles a la hora de abordar la patología del bíceps, aunque la técnica PITT es más rápida, económica y accesible

Statistical Wiring of Thalamic Receptive Fields Optimizes Spatial Sampling of the Retinal Image

SummaryIt is widely assumed that mosaics of retinal ganglion cells establish the optimal representation of visual space. However, relay cells in the visual thalamus often receive convergent input from several retinal afferents and, in cat, outnumber ganglion cells. To explore how the thalamus transforms the retinal image, we built a model of the retinothalamic circuit using experimental data and simple wiring rules. The model shows how the thalamus might form a resampled map of visual space with the potential to facilitate detection of stimulus position in the presence of sensor noise. Bayesian decoding conducted with the model provides support for this scenario. Despite its benefits, however, resampling introduces image blur, thus impairing edge perception. Whole-cell recordings obtained in vivo suggest that this problem is mitigated by arrangements of excitation and inhibition within the receptive field that effectively boost contrast borders, much like strategies used in digital image processing

The control challenges for the Next Generation Gravity Mission

Several activities are on going in preparation of a "Next Generation Gravity Mission" (NGGM) aimed at measuring the temporal variations of the Earth gravity field over a long time span with high spatial resolution and high temporal resolution. The most appropriate measurement technique identified for such mission is the "Low-Low Satellite-Satellite Tracking" in which two satellites flying in loose formation in a low Earth orbit act as proof masses immersed in the Earth gravity field. The distance variation between the satellites and the non-gravitational accelerations of the satellites, measured respectively by a laser interferometer and by ultra-sensitive accelerometers, are the fundamental observables from which the Earth gravitational field is obtained. The control system for the NGGM must fulfil the challenging combination of requirements for the orbit and formation maintenance, attitude stabilisation, drag compensation and microradian laser beam pointing. This paper presents the assessment and the preliminary design of the NGGM control system, performed by Thales Alenia Space Italia and Politecnico di Torino for the European Space Agency

La infiltración en función del contenido inicial de humedad.

En el CNI Palmira se efectuó un estudio de infiltración por el método de infiltrómetros en una serie de suelos pesados (Haplustoll), teniendo en cuenta como variable el contenido de humedad inicial del suelo. Se compararon 3 modelos básicos: Philip, Kostiakov y una ecuación cuadrática. Los resultados indican que el modelo de Kostiakov es el de mejor ajuste (R elevado a la 2 igual a 0.9). Mediante análisis de regresión se obtuvo una expresión matemática de tipo potencial, que expresa el coeficiente c' en función de la humedad inicial (H sub 1), para la ecuación de Kostiakov. El exponente alfa no presentó valores significativos que permitieran afirmar con certeza que la humedad lo afecta. Se concluye que en la determinación de la infiltración se debe tener en cuenta el contenido inicial de humedad para lograr una mejor caracterización de los índices de infiltración que garanticen un adecuado manejo del agua a nivel predia

Persistence of HPV infection and risk of high-grade cervical intraepithelial neoplasia in a cohort of Colombian women

Little is known about the dynamics of human papillomavirus (HPV) infection and subsequent development of high-grade cervical intraepithelial neoplasia (CIN2/3), particularly in women >30 years of age. This information is needed to assess the impact of HPV vaccines and consider new screening strategies. A cohort of 1728 women 15–85 years old with normal cytology at baseline was followed every 6 months for an average of 9 years. Women with squamous intraepithelial lesions were referred for biopsy and treatment. The Kaplan–Meier method was used to estimate the median duration of infection and Cox regression analysis was undertaken to assess determinants of clearance and risk of CIN2/3 associated with HPV persistence. No difference in the likelihood of clearance was observed by HPV type or woman's age, with the exception of lower clearance for HPV16 infection in women under 30 years of age. Viral load was inversely associated with clearance. In conclusion, viral load is the main determinant of persistence, and persistence of HPV16 infections carry a higher risk of CIN2/3