Almost invariably, when a device is disassembled, it is taken apart in the reverse order from which it was assembled. There is growing evidence that the same logic applies to the human brain. Those faculties that breakdown first during aging are those that mature last during development. Dr. Dumas’ team has identified some of the final steps of hippocampal maturation in rodents on molecular, physiological and behavioral levels and found some overlap with reverse changes that happen in early aging. Dr. Dumas’ research is intended to better understand the mechanisms of memory loss related to normal aging and to be able to rectify them in order to improve quality of life for elderly individuals and reduce medical costs associated with senescence.]]>
Physical therapy is a grueling process usually met with limited gains and quickly reached plateaus of recovery. Many robotic devices have been incorporated into the clinic because they provide a highly repeatable and accurate training experience while lessening the burden of the therapist. Unfortunately one of the more popular devices, the Lokomat robotic gait trainer, has fallen out of favor because early studies on the effectiveness of the device showed mixed results. This is no reason to stop using the tool, but reason to learn how to use the tool better. Standard robotic gait training therapy involves guiding the injured limbs through a healthy stepping pattern. But healthy patterns may not be the best treatment following neurological injury. With a fully programmable robotic device there are innumerable variations to the training experience available. The use of rodent models enables us to test novel robotic gait training patterns and investigate their ability to improve overground locomotion as well as their ability to change the neuronal structure of the spinal cord following injury. We are currently investigating the effects of training in applied force fields instead of guided stepping patterns. Specifically, we are robotically training rats in viscous fields as well as negative viscosity fields after an incomplete cervical spinal cord injury and measuring the changes in the overground locomotion. Additionally, we are using manganese enhanced MRI techniques and diffusion tensor imaging tractography to investigate how our novel gait training induces changes in the activity of the spinal interneurons around the injury site. We hope that these studies will uncover better training techniques that can be quickly applied to the clinical setting to improve the locomotion of patients following neurological injury.
Regulated secretion is a critical process by which cells deliver molecules to the cell surface and extracellular space. Secreted cargo is synthesized in the endoplasmic reticulum, traverses the Golgi apparatus and is subsequently loaded into secretory vesicles. Secretion occurs in response to an external stimulus and involves directed vesicle movement, docking with the plasma membrane, fusion pore formation, and vesicle collapse to release cargo. Aberrant secretion is the cause of many human diseases. Defining the factors involved in secretion is crucial to develop therapeutic targets for these diseases.
Drosophila salivary glands are the largest secretory structures of the fly and represent a tractable experimental system for studying the factors that regulate hormone-induced secretion. To this end, I perform real time imaging on living salivary glands to elucidate the mechanisms and kinetics of secretion. By using confocal and spinning disc microscopy in combination with fluorescently tagged proteins, I can directly visualize the steps involved in cargo secretion and the role of the actin cytoskeleton during regulated secretion. By combining these approaches with Drosophila genetics I am defining the discrete events of regulated secretion and novel genes involved in this biologically relevant process.
Researchers in the field of positive psychology have discovered a number of benefits associated with positive emotions. Dr. Cabrera will discuss how these benefits contribute to success and well-being and will highlight specific strategies that can be used to create a more positive workplace where employees can thrive. She will also present a second dimension, in addition to positive emotions, that scientists believe is essential for our well-being.
I want to present four theses of possible interest. First, that economic theory today has not caught up with the changes in the world since Adam Smith and David Ricardo. Then externalities were comparatively rare and unusual. Today they are pervasive, thanks to urbanization, networking and globalization. The financial externalities associated with bubbles now far exceed in damage the profits to the bubble-makers. Second, economic growth since that time has been demand driven because energy prices kept falling,– on average — until the beginning of this century. Future growth is not guaranteed in a world of “peak oil”, and oil price bubbles. It is not certain that our grandchildren will be much richer than we are. Secular stagnation May be caused by energy constraints. Third, the policy response by central banks – low and lower interest rates, creates the condition for the next bubble. This cannot continue. Fourth, there is a profit opportunity approaching with a huge payoff If grasped it will kickstart growth, reduce unemployment, ameliorate the Greenhouse effect and help solve the problems of the pension funds.]]>
Electron microscopes (EM) can now provide the nanometer resolution that is needed to image synapses, and therefore connections, while Light Microscopes (LM) see at the micrometer resolution required to model the 3D structure of the dendritic network. Since both the arborescence and the connections are integral parts of the brain’s wiring diagram, combining these two modalities is critically important.
In this talk, I will therefore present our approach to building the dendritic arborescence, to segmenting intra-neuronal structures from EM images, and to registering the resulting models. I will also argue that the techniques that are in wide usage in the Computer Vision and Machine Learning community are just as applicable in this context.]]>
Assistant Professor, Georgetown University Medical Center Department of Rehabilitation Medicine, Interdisciplinary Program in Neuroscience, and Center for Brain Plasticity and Recovery
Research Scientist, MedStar National Rehabilitation Hospital Neuroscience Research Center and Mechanisms of Therapeutic Rehabilitation Laboratory
For over 2 decades, the neural mechanisms of motor recovery in mildly impaired stroke patients with full or partial recovery of hand movements have been widely studied. Comparatively little is known about more severely impaired patients who have little or no voluntary hand movement but retain some voluntary movement of the shoulder and elbow. The latter group is large and represents those in particular need of interventions to enhance recovery. The mechanisms of recovery in upper arm muscles of more severely impaired patients are likely to differ from those identified in recovery of hand movements in patients with mild impairment. The results of recent studies aimed at identifying mechanisms of reaching movement recovery in severely impaired stroke patients will be discussed.
The brain is a densely and precisely wired circuit made of heterogeneous cells, which themselves are complex computational devices made of an incredible repertoire of molecules. Our group develops tools for mapping, recording from, controlling, and building brain circuits, in order to reveal how they work, as well as to open up new therapeutic avenues. We have developed genetically-encoded reagents that, when expressed in specific neurons, enable their electrical activities to be precisely driven or silenced in response to millisecond timescale pulses of light. I will give an overview of these optogenetic tools, adapted from natural photosensory and photosynthetic proteins, and discuss new tools we are developing, including molecules that enable multiplexed, noninvasive, and ultraprecise optical neural control, even of endogenous signaling pathways. We are developing, often working in interdisciplinary collaborations, microfabricated hardware to enable complex and distributed neural circuits to be controlled and recorded in a fully 3-D fashion, new kinds of microscopes capable of whole-nervous system neural activity imaging, robots that can automatically record neurons intracellularly and integratively in live brain, and strategies for building 3-D brain circuits in vitro. We aim to provide these tools to the neuroscience community in order to open up new fundamental as well as clinically relevant explorations of how to observe and repair brain circuits, and to apply these tools systematically to the mapping and engineering of entire brains.