Neuroimaging and Optogenetics
Neuroimaging and optogenetics are tools, but modern neuroimaging has transformed our ability to study dynamic processes in the nervous system in a non-invasive, rapid, and real-time manner. The University of Minnesota has one of the world’s premier high and ultrahigh field function magnetic resonance imaging (fMRI) facilities in the Center of Magnetic Resonance Research. It was funded by the National Center for Research Resources and now by the National Institute of Biomedical Imaging and Bioengineering, this Center focuses not only on primary research on the brain but also on the development of unique methods and instrumentation for the acquisition of structural, functional, and biochemical information non-invasively in animals models and humans. The Center has ultrahigh field magnets (7 tesla and above) and houses some of the most advanced MR instrumentation in the world. In addition the Veterans Administration Medical Center houses a magneto-encephalography (MEG) system to uses an array of over 200 axial gradiometers to detect small magnetic fields produced by neural activity. These are other neuroimaging facilities give the faculty and trainees in the Graduate Program in Neuroscience a huge technological advantage. Optogenetics is a technique that allows the use of light to control cells in the nervous system that have been modified genetically to express light-sensitive ion channels. This was a huge technical advance in our ability to control and monitor individual neurons in living tissue and measure the effects of these manipulations in real-time.
Many laboratories use imaging as part of their armamentarium to investigate brain function. These include studies on: neural basis and mechanisms of motor learning; flavoprotein fluorescence and calcium dye imaging to visualize neural activity in real time in cerebellar circuits; fMRI to study vision, visual attention, visual perception, and visual cognition; NMR spectroscopy at 9.4 Tesla to detect brain function and cell signaling in development of learning and memory; high field fMRI to study neural mechanisms of cognitive processes in motor behavior in both non-human primates and humans; both intrinsic optic imaging techniques and fMRI to study single and multiple neuronal populations that control visually guided behaviors; combined electrophysiological and fMRI imaging to improve spatio-temporal resolution of brain function; optogenetic approaches to understand the pathophysiology of epilepsy; use of MEG to understand long-term learning; diffusion tensor imaging to assess white matter changes as they relate to schizophrenia; fMRI combined with behavioral genetics to understand the neuropathology of schizophrenia and the normal control of task performance; functional magnetic resonance spectroscopy (fMRS) to assess quantitative changes in tissue metabolism, structure, and function in disorders of the nervous system; perfusion MRI with arterial spin labeling to detect the impact of diabetes and hypoglycemia on brain function; calcium imaging techniques to assess activity of 100s of neurons in neural networks in an epilepsy model; how well does the BOLD fMRI measure underlying neural activity; fMRS to understand brain metabolism and function in neurodegenerative disorders including spinocerebellar ataxias and Parkinson’s disease; fMRI and PET scanning to understand neural network dysfunction in psychiatric disorders; high-field 1H and 13C NMR spectroscopy to study cerebral metabolism in brain function; and high resolution fMRI to understand higher order brain function. Optogentics is used to: monitor neuronal function in epilepsy; understand neuronal activation in drugs of abuse; how neurons sense, integrate, and exchange information; assess therapies for neuropsychiatric disorders; and to understand the genetic and molecular changes involved in brain disorders such as autism and mental illness.