Cellular Imaging of Visual Cortex Reveals the Spatial and Functional Organization of Spontaneous Activity

The cerebral cortex is never silent; even in primary sensory areas there is ongoing neural activity in the absence of sensory input. Correlations in spontaneous activity can provide clues about network structure, but it has been difficult to record from enough nearby neurons to sample these correlations well. We used in vivo two-photon calcium imaging to demonstrate sparse patterns of correlated spontaneous activity among groups of ∼150 simultaneously imaged cells. In cat visual cortex, correlations fell off sharply with distance, by 50% within ∼240 μm, but in the rat there was little dependence on spatial separation up to 400 μm. In both species, cells that responded best to visual contours of a specific orientation were spontaneously co-active, suggesting that functionally related cells are organized into distinct subnetworks. Although these subnetworks are clustered in the cat, they are intermingled in the rodent, arguing for specific connections within the local cortical network

M.I.N.G., Mars Investment for a New Generation: Robotic construction of a permanently manned Mars base

A basic procedure for robotically constructing a manned Mars base is outlined. The research procedure was divided into three areas: environment, robotics, and habitat. The base as designed will consist of these components: two power plants, communication facilities, a habitat complex, and a hangar, a garage, recreation and manufacturing facilities. The power plants will be self-contained nuclear fission reactors placed approx. 1 km from the base for safety considerations. The base communication system will use a combination of orbiting satellites and surface relay stations. This system is necessary for robotic contact with Phobos and any future communication requirements. The habitat complex will consist of six self-contained modules: core, biosphere, science, living quarters, galley/storage, and a sick bay which will be brought from Phobos. The complex will be set into an excavated hole and covered with approximately 0.5 m of sandbags to provide radiation protection for the astronauts. The recreation, hangar, garage, and manufacturing facilities will each be transformed from the four one-way landers. The complete complex will be built by autonomous, artificially intelligent robots. Robots incorporated into the design are as follows: Large Modular Construction Robots with detachable arms capable of large scale construction activities; Small Maneuverable Robotic Servicers capable of performing delicate tasks normally requiring a suited astronaut; and a trailer vehicle with modular type attachments to complete specific tasks; and finally, Mobile Autonomous Rechargeable Transporters capable of transferring air and water from the manufacturing facility to the habitat complex

Diverse receptive fields in the lateral geniculate nucleus during thalamocortical development

articles Early studies of the effects of visual deprivation demonstrated the essential role of sensory experience in the development of the highly specific connections from thalamus to visual cortex 1 . Since then, the mechanisms underlying this refinement process have been extensively investigated, and models that attempt to explain it have been proposed The receptive-field shapes of the geniculate inputs to cortex may also be important in thalamocortical development. Most models of thalamocortical development assume geniculate inputs to be a homogeneous pool of concentric, on-or off-center cells, similar to those found in the adult The maturation of retinogeniculate connections is almost certainly the mechanism for the reduction of receptive-field size in the developing LGN The final phase of retinogeniculate maturation overlaps with the critical period for thalamocortical development. In kittens, spatial receptive-field maturation in the LGN occurs during the first 2-3 weeks after eye opening 14 . The maturation of ocular dominance columns 3 and orientation selectivity 20-24 in visual cortex occur during the first few weeks after eye opening in cats and ferrets. It is thus probable that imprecise connectivity from retina to LGN at this stage influences thalamocortical development RESULTS We recorded extracellularly from 112 neurons in layers A and A1 of the lateral geniculate nucleus of the ferret: 88 neurons in immature animals at postnatal day 31-55 (P31-P55) and 24 in adults. In addition, we recorded, in the optic tract, responses of five retinal ganglion cells from P37 and P39 animals. Eyes first open on postnatal day 30-34 in the ferret 25 . Spatial structure of developing geniculate receptive fields For all cells studied, we mapped the receptive fields with a whitenoise stimulus that consisted of 16 × 16 squares (pixels), each modulated in time by a binary temporal sequence 26 . Receptivefield maps from LGN cells in adult ferrets qualitatively resembled those obtained in previous studies of the cat LGN 27 : they were concentric and had antagonistic center/surround organization Trial-to-trial robustness of receptive-field structure To ensure that the receptive fields we mapped belonged to single cells, great care was taken to verify the quality of the recordings. Only well-isolated action potentials, as assessed by online Most models of thalamocortical development in the visual system assume a homogeneous population of thalamic inputs to the cortex, each with concentric on-or off-center receptive fields. To test this, we made high-resolution spatial maps of receptive fields in the developing ferret lateral geniculate nucleus (LGN). Developing receptive fields (RFs), had a variety of shapes: some concentric, others elongated (like adult cortical receptive fields) and some with 'hot spots' of sensitivity. These receptive fields seemed to arise from convergence of multiple retinal afferents onto LGN neurons. We present a Hebbian model whereby imprecise retinogeniculate connections help refine geniculocortical connections, sharpening both thalamocortical topography and perhaps orientation selectivity

Chronic Cellular Imaging of Entire Cortical Columns in Awake Mice Using Microprisms

SummaryTwo-photon imaging of cortical neurons in vivo has provided unique insights into the structure, function, and plasticity of cortical networks, but this method does not currently allow simultaneous imaging of neurons in the superficial and deepest cortical layers. Here, we describe a simple modification that enables simultaneous, long-term imaging of all cortical layers. Using a chronically implanted glass microprism in barrel cortex, we could image the same fluorescently labeled deep-layer pyramidal neurons across their entire somatodendritic axis for several months. We could also image visually evoked and endogenous calcium activity in hundreds of cell bodies or long-range axon terminals, across all six layers in visual cortex of awake mice. Electrophysiology and calcium imaging of evoked and endogenous activity near the prism face were consistent across days and comparable with previous observations. These experiments extend the reach of in vivo two-photon imaging to chronic, simultaneous monitoring of entire cortical columns.Video Abstrac

The Student Movement Volume 107 Issue 17: I Dreamed a Dream : AU One Day Closer to Spring

HUMANS Joyful Resilience: An Interview with Artist Jasmin Hislop, Interviewed by Solana Campbell Love is in the Air, Interviewed by Grace No Working at the Writing Center: Interview With Camilia Howell, Interviewed by Gloria Oh Arts & Entertainment Blackventist Praise, Nathaniel Reid Ceramics: Revival of the Art Elective, Ysabelle Fernando Currently: The Romantics, Solana Campbell Freedom: a Black History Month Playlist, Amelia Stefanescu NEWS Dinosaurs Under the Microscope: Mary Higby Schweitzer Visits Andrews, Alannah Tjhatra Les Misérables at the Chicago Cadillac Palace Theatre, Gloria Oh IDEAS Engineering What We Eat: The Past, Present, and Future of Genetically Modified Food, Alexander Navarro Russia and Ukraine: New Year, New Direction?, Melissa Moore Stress and Video Games, Rachel Ingram-Clay PULSE Can Political Parties Be Inherently Christ-Like?, Wambui Karanja Is Honors an Advantage to our Students?, Melissa Moore The Wellness Center Happenings, Lexie Dunham LAST WORD Why Read? Practice Makes Better. Terika Williamshttps://digitalcommons.andrews.edu/sm-107/1016/thumbnail.jp

The Student Movement Volume 107 Issue 13: We\u27ve Got the Spirit: Students Celebrate Dr. Luxton

HUMANS Best of Bon Appetit, Nora Martin Interview with the Dean of Lamson and Meier Halls, Interviewed by: Grace No The Joy of Japan, Interviewed by: Gloria Oh ARTS & ENTERTAINMENT A Creation Adventure, Nathaniel Reid Currently: Velma, Solana Campbell Suite Dreams for Sweet Dreams, Skylor Stark Where do I Find God? Part II, Anonymous NEWS AUSA Celebrates 100 Years of Student-Led Action, Andrew Francis Response to A House Divided Story, Christon Arthur, Provost Where\u27s the Harm in True Crime?. Abigail Kim IDEAS Redefining Free Agency in Sports, Andrew Francis Flying Cars of 2030, Rachel Ingram-Clay The Spooky Nature of Our Physical World, Alexander Navarro The State of AI, Abby Shim PULSE Debunking Myths Surrounding J.N. Andrews Honors Program, Gloria Oh Our Dear AU: A Spirit Week Tour, Lexie Dunham Romance and Reading, Gloria Oh LAST WORD An Ode to Tea, Alexander J. Hesshttps://digitalcommons.andrews.edu/sm-107/1012/thumbnail.jp

The Student Movement Volume 107 Issue 11: Have a Merry Christmas! XOXO, The Student Movement

HUMANS Coping with Finals, Solana Campbell Meet Jea Erazo, AUSA Public Relations Officer. Interviewed by: Caryn Cruz Remembering Sharon Dudgeon, Grace No Women in STEM: Olivia Joyce, Interviewed by: Gloria Oh ARTS & ENTERTAINMENT Football Sunday, Nathaniel Reid, Skylor Stark Student Picks: Christmas Classics, Ysabelle Fernando NEWS AFIA x MLS Christmas Party, Ceiry Flores Boycotts and Bans at the Qatar World Cup, Hannah Cruse In Loving Memory of Seth Williams, Gloria Oh IDEAS How Do We Address Queer Violence?, Alexander J. Hess Is Reality Really Real When You Aren\u27t Really Looking?, Alexander Navarro Reflecting on Christmas Traditions, Rachel Ingram-Clay The New Era of Book Bans, Elizabeth Getahun Why is Everyone so Happy During Christmastime?, Kayla-Hope Bruno PULSE Bon Appétit and the Threat to Cultural Autonomy, Wambui Karanja It\u27s OrnaMEANT to be a Wonderful Christmastime, Lexie Dunham It\u27s the Most Stressful Time of the Year, Reagan McCain Qatar Controversy: The Shadow Behind the World Cup, Melissa Moore Reflections on the Semester and Plans for Break, Elizabeth Dovich LAST WORD A Student Movement Christmas, The Student Movement Staffhttps://digitalcommons.andrews.edu/sm-107/1010/thumbnail.jp

Galactic Center Research: Manifestations of the Central Black Hole

This review summarizes a few of the frontiers of Galactic center research that are currently the focus of considerable activity and attention. It is aimed at providing a necessarily incomplete sketch of some of the timely work being done on phenomena taking place in, or originating in, the central few parsecs of the Galaxy, with particular attention to topics related to the Galactic black hole (GBH). We have chosen to expand on the following exciting topics: 1) the characterization and the implications for the variability of emission from the GBH, 2) the strong evidence for a powerful X-ray flare in the Galactic center within the past few hundred years, and the likelihood that the GBH is implicated in that event, 3) the prospects for detecting the "shadow" of the GBH, 4) an overview of the current state of research on the central S-star cluster, and what has been learned from the stellar orbits within that cluster, and 5) the current hypotheses for the origin of the G2 dust cloud that is projected to make a close passage by the GBH in 2013.Comment: Review article, in press with Review of Astronomy and Astrophysic