A Sparse Object Coding Scheme in Area V4

SummarySparse coding has long been recognized as a primary goal of image transformation in the visual system [1–4]. Sparse coding in early visual cortex is achieved by abstracting local oriented spatial frequencies [5] and by excitatory/inhibitory surround modulation [6]. Object responses are thought to be sparse at subsequent processing stages [7, 8], but neural mechanisms for higher-level sparsification are not known. Here, convergent results from macaque area V4 neural recording and simulated V4 populations trained on natural object contours suggest that sparse coding is achieved in midlevel visual cortex by emphasizing representation of acute convex and concave curvature. We studied 165 V4 neurons with a random, adaptive stimulus strategy to minimize bias and explore an unlimited range of contour shapes. V4 responses were strongly weighted toward contours containing acute convex or concave curvature. In contrast, the tuning distribution in nonsparse simulated V4 populations was strongly weighted toward low curvature. But as sparseness constraints increased, the simulated tuning distribution shifted progressively toward more acute convex and concave curvature, matching the neural recording results. These findings indicate a sparse object coding scheme in midlevel visual cortex based on uncommon but diagnostic regions of acute contour curvature

Active flexible concentric ring electrode for non-invasive surface bioelectrical recordings

Bioelectrical surface recordings are usually performed by unipolar or bipolar disc electrodes even though they entail the serious disadvantage of having poor spatial resolution. Concentric ring electrodes give improved spatial resolution, although this type of electrode has so far only been implemented in rigid substrates and as they are not adapted to the curvature of the recording surface may provide discomfort to the patient. Moreover, the signals recorded by these electrodes are usually lower in amplitude than conventional disc electrodes. The aim of this work was thus to develop and test a new modular active sensor made up of concentric ring electrodes printed on a flexible substrate by thick-film technology together with a reusable battery-powered signal-conditioning circuit. Simultaneous ECG recording with both flexible and rigid concentric ring electrodes was carried out on ten healthy volunteers at rest and in motion. The results show that flexible concentric ring electrodes not only present lower skin electrode contact impedance and lower baseline wander than rigid electrodes but are also less sensitive to interference and motion artefacts. We believe these electrodes, which allow bioelectric signals to be acquired non-invasively with better spatial resolution than conventional disc electrodes, to be a step forward in the development of new monitoring systems based on Laplacian potential recordings.This research was supported in part by the Ministerio de Ciencia y Tecnologia de Espana (TEC2010-16945) and by the Universitat Politecnica de Valencia (PAID 2009/10-2298). The proof-reading of this paper was funded by the Universitat Politecnica de Valencia, Spain.Prats Boluda, G.; Ye Lin, Y.; García Breijo, E.; Ibáñez Civera, FJ.; Garcia Casado, FJ. (2012). Active flexible concentric ring electrode for non-invasive surface bioelectrical recordings. Measurement Science and Technology. 23(12):1-10. https://doi.org/10.1088/0957-0233/23/12/125703S1102312Malmivuo, J., & Plonsey, R. (1995). BioelectromagnetismPrinciples and Applications of Bioelectric and Biomagnetic Fields. doi:10.1093/acprof:oso/9780195058239.001.0001Gevins, A. (1989). Dynamic functional topography of cognitive tasks. Brain Topography, 2(1-2), 37-56. doi:10.1007/bf01128842Bradshaw, L. A., Wijesinghe, R. S., & Wikswo, Jr., J. P. (2001). Spatial Filter Approach for Comparison of the Forward and Inverse Problems of Electroencephalography and Magnetoencephalography. Annals of Biomedical Engineering, 29(3), 214-226. doi:10.1114/1.1352641Bradshaw, L. A., Richards, W. O., & Wikswo, J. P. (2001). Volume conductor effects on the spatial resolution of magnetic fields and electric potentials from gastrointestinal electrical activity. Medical & Biological Engineering & Computing, 39(1), 35-43. doi:10.1007/bf02345264Garcia-Casado, J., Martinez-de-Juan, J. L., & Ponce, J. L. (2005). Noninvasive Measurement and Analysis of Intestinal Myoelectrical Activity Using Surface Electrodes. IEEE Transactions on Biomedical Engineering, 52(6), 983-991. doi:10.1109/tbme.2005.846730SippensGroenewegen, A., Peeters, H. A. P., Jessurun, E. R., Linnenbank, A. C., Robles de Medina, E. O., Lesh, M. D., & van Hemel, N. M. (1998). Body Surface Mapping During Pacing at Multiple Sites in the Human Atrium. Circulation, 97(4), 369-380. doi:10.1161/01.cir.97.4.369Lian, J., Li, G., Cheng, J., Avitall, B., & He, B. (2002). Body surface Laplacian mapping of atrial depolarization in healthy human subjects. Medical & Biological Engineering & Computing, 40(6), 650-659. doi:10.1007/bf02345304Wu, D., Tsai, H. C., & He, B. (1999). On the Estimation of the Laplacian Electrocardiogram during Ventricular Activation. Annals of Biomedical Engineering, 27(6), 731-745. doi:10.1114/1.224Koka, K., & Besio, W. G. (2007). Improvement of spatial selectivity and decrease of mutual information of tri-polar concentric ring electrodes. Journal of Neuroscience Methods, 165(2), 216-222. doi:10.1016/j.jneumeth.2007.06.007Prats-Boluda, G., Garcia-Casado, J., Martinez-de-Juan, J. L., & Ye-Lin, Y. (2011). Active concentric ring electrode for non-invasive detection of intestinal myoelectric signals. Medical Engineering & Physics, 33(4), 446-455. doi:10.1016/j.medengphy.2010.11.009He, B., & Cohen, R. J. (1992). Body surface Laplacian mapping of cardiac electrical activity. The American Journal of Cardiology, 70(20), 1617-1620. doi:10.1016/0002-9149(92)90471-aBesio, W., Aakula, R., Koka, K., & Dai, W. (2006). Development of a Tri-polar Concentric Ring Electrode for Acquiring Accurate Laplacian Body Surface Potentials. Annals of Biomedical Engineering, 34(3), 426-435. doi:10.1007/s10439-005-9054-8Ye-Lin, Y., Garcia-Casado, J., Prats-Boluda, G., Ponce, J. L., & Martinez-de-Juan, J. L. (2009). Enhancement of the non-invasive electroenterogram to identify intestinal pacemaker activity. Physiological Measurement, 30(9), 885-902. doi:10.1088/0967-3334/30/9/002Hjorth, B. (1975). An on-line transformation of EEG scalp potentials into orthogonal source derivations. Electroencephalography and Clinical Neurophysiology, 39(5), 526-530. doi:10.1016/0013-4694(75)90056-5Perrin, F., Pernier, J., Bertnard, O., Giard, M. ., & Echallier, J. . (1987). Mapping of scalp potentials by surface spline interpolation. Electroencephalography and Clinical Neurophysiology, 66(1), 75-81. doi:10.1016/0013-4694(87)90141-6Nunez, P. L., & Westdorp, A. F. (1994). The surface laplacian, high resolution EEG and controversies. Brain Topography, 6(3), 221-226. doi:10.1007/bf01187712Srinivasan, R., Nunez, P. L., Tucker, D. M., Silberstein, R. B., & Cadusch, P. J. (1996). Spatial sampling and filtering of EEG with spline Laplacians to estimate cortical potentials. Brain Topography, 8(4), 355-366. doi:10.1007/bf01186911Farina, D., & Cescon, C. (2001). Concentric-ring electrode systems for noninvasive detection of single motor unit activity. IEEE Transactions on Biomedical Engineering, 48(11), 1326-1334. doi:10.1109/10.959328G. Besio, C. C. Lu, P. P. Tarjan, W. (2001). A Feasibility Study for Body Surface Cardiac Propagation Maps of Humans from Laplacian Moments of Activation. Electromagnetics, 21(7-8), 621-632. doi:10.1080/027263401752246243Li, G., Wang, Y., Lin, L., Jiang, W., Wang, L. L., Lu, S. C.-Y., & Besio, W. G. (2005). Active Laplacian electrode for the data-acquisition system of EHG. Journal of Physics: Conference Series, 13, 330-335. doi:10.1088/1742-6596/13/1/077Engel, J., Chen, J., & Liu, C. (2003). Development of polyimide flexible tactile sensor skin. Journal of Micromechanics and Microengineering, 13(3), 359-366. doi:10.1088/0960-1317/13/3/302Papakostas, T. V., Lima, J., & Lowe, M. (s. f.). A large area force sensor for smart skin applications. Proceedings of IEEE Sensors. doi:10.1109/icsens.2002.1037366Stieglitz, T. (2001). Flexible biomedical microdevices with double-sided electrode arrangements for neural applications. Sensors and Actuators A: Physical, 90(3), 203-211. doi:10.1016/s0924-4247(01)00520-9Hamilton, P. S., & Tompkins, W. J. (1986). Quantitative Investigation of QRS Detection Rules Using the MIT/BIH Arrhythmia Database. IEEE Transactions on Biomedical Engineering, BME-33(12), 1157-1165. doi:10.1109/tbme.1986.325695Besio, W., & Chen, T. (2007). Tripolar Laplacian electrocardiogram and moment of activation isochronal mapping. Physiological Measurement, 28(5), 515-529. doi:10.1088/0967-3334/28/5/006Besio, G., Koka, K., Aakula, R., & Weizhong Dai. (2006). Tri-polar concentric ring electrode development for Laplacian electroencephalography. IEEE Transactions on Biomedical Engineering, 53(5), 926-933. doi:10.1109/tbme.2005.863887Setti, L., Fraleoni-Morgera, A., Ballarin, B., Filippini, A., Frascaro, D., & Piana, C. (2005). An amperometric glucose biosensor prototype fabricated by thermal inkjet printing. Biosensors and Bioelectronics, 20(10), 2019-2026. doi:10.1016/j.bios.2004.09.022Reddy, A. S. G., Narakathu, B. B., Atashbar, M. Z., Rebros, M., Rebrosova, E., & Joyce, M. K. (2011). Gravure Printed Electrochemical Biosensor. Procedia Engineering, 25, 956-959. doi:10.1016/j.proeng.2011.12.235Gruetzmann, A., Hansen, S., & Müller, J. (2007). Novel dry electrodes for ECG monitoring. Physiological Measurement, 28(11), 1375-1390. doi:10.1088/0967-3334/28/11/005LI, G., LIAN, J., SALLA, P., CHENG, J., RAMACHANDRA, I., SHAH, P., … HE, B. (2003). Body Surface Laplacian Electrocardiogram of Ventricular Depolarization in Normal Human Subjects. Journal of Cardiovascular Electrophysiology, 14(1), 16-27. doi:10.1046/j.1540-8167.2003.02199.

Patrolling monocytes control tumor metastasis to the lung

The immune system plays an important role in regulating tumor growth and metastasis. Classical monocytes promote tumorigenesis and cancer metastasis, but how nonclassical "patrolling" monocytes (PMo) interact with tumors is unknown. Here we show that PMo are enriched in the microvasculature of the lung and reduce tumor metastasis to lung in multiple mouse metastatic tumor models. Nr4a1-deficient mice, which specifically lack PMo, showed increased lung metastasis in vivo. Transfer of Nr4a1-proficient PMo into Nr4a1-deficient mice prevented tumor invasion in the lung. PMo established early interactions with metastasizing tumor cells, scavenged tumor material from the lung vasculature, and promoted natural killer cell recruitment and activation. Thus, PMo contribute to cancer immunosurveillance and may be targets for cancer immunotherapy

Perfectionism, burnout and engagement in youth sport: The mediating role of basic psychological needs

© 2016 Elsevier Ltd. Recent research indicates perfectionistic concerns and perfectionistic strivings share divergent associations with athlete burnout and athlete engagement. Guided by self-determination theory, the present study examined whether these associations were explained by basic psychological needs. Youth athletes (n = 222, M age = 16.01, SD = 2.68) completed measures of multidimensional perfectionism, athlete burnout, athlete engagement, basic psychological need satisfaction and thwarting. Structural equation modelling revealed that basic psychological need satisfaction and thwarting mediated the perfectionism-engagement and perfectionism-burnout relationships. Perfectionistic concerns shared a negative relationship (via need satisfaction) with athlete engagement and a positive relationship (via need satisfaction and thwarting) with athlete burnout. In contrast, perfectionistic strivings shared a positive relationship (via need satisfaction) with athlete engagement and a negative relationship (via need satisfaction and thwarting) with athlete burnout. The findings highlight the role of basic psychological needs in explaining the differential associations that perfectionistic concerns and strivings share with athlete burnout and engagement

Outcome and serum ion determination up to 11 years after implantation of a cemented metal-on-metal hip prosthesis

Background and purpose Little is known about the long-term outcome of cemented metal-on-metal hip arthroplasties. We evaluated a consecutive series of metal-on-metal polyethylene-backed cemented hip arthroplasties implanted in patients under 60 years of age