Events

Apr 16, 2014
12:00 PM
Seminar room 2204, 149 13th St., Charlestown Navy Yard

Richard Born, MD
Harvard Medical School
Department of Neurobiology
 
Feedback connections are prevalent throughout the cerebral cortex, yet their function remains poorly understood. Previous studies in anesthetized monkeys found that inactivating feedback from extrastriate visual cortex produced effects in striate cortex that were relatively weak, generally suppressive, largest for visual stimuli confined to the receptive field center, and detectable only at low stimulus contrast. We studied the influence of corticocortical feedback in alert monkeys using cortical cooling to reversibly inactivate visual areas 2 (V2) and 3 (V3) while characterizing receptive field properties in primary visual cortex (V1).We show that inactivation of feedback results in both response suppression and facilitation for stimuli restricted to the receptive field center, in most cases leading to a small reduction in the degree of orientation selectivity but no change in orientation preference. For larger-diameter stimuli that engage regions beyond the center of the receptive field, eliminating feedback from V2/V3 results in strong and consistent response facilitation, effectively reducing the strength of surround suppression in V1 for stimuli of both low and high contrast. For extended contours, eliminating feedback had the effect of reducing end stopping. Inactivation effects were largest for neurons that exhibited strong surround suppression before inactivation, and their timing matched the dynamics of surround suppression under control conditions. Our results provide direct evidence that feedback contributes to surround suppression, which is an important source of contextual influences essential to vision.

Apr 17, 2014
12:00 PM
Seminar room 2204, 149 13th St., Charlestown Navy Yard

Special Guest Seminar
 
Paul Vaska, Ph.D.
Stony Brook University
Brookhaven National Laboratory
 
We have developed a high-performance and flexible PET imaging platform with a resolution of ~1.5 mm, and employed it in several novel research paradigms.  These include PET imaging of the brain of a conscious and behaving rat, and simultaneous PET and MRI imaging in rodents at a field strength of 9.4 T.  I will also discuss our progress in scaling these systems up for human applications.  We have built an imaging system to improve the diagnosis of breast cancer using simultaneous PET/MRI and acquired pilot clinical data, and we are developing plans for a highly mobile human brain PET for both basic neuroscience and clinical applications such as the study of the acute phase of mild traumatic brain injury.

Apr 28, 2014 to May 09, 2014
(All day)
Building 149, Charlestown Navy Yard, Charlestown, Mass.

The goal of this ambitious workshop is to demonstrate the ways in which a large variety of techniques are being applied to questions in human brain function. Participants will receive exposure to MRI, FMRI, DTI, DSI, MRS, PET, EEG, MEG, NIRS, DOT, TMS, and a variety of molecular and computational approaches to studying human brain function in vivo. There will also be some discussion of more invasive techniques such as implanted electrodes and direct cortical stimulation---tools that are used before and during surgery.

To bring this heterogeneous collection of technologies together, a number of unifying themes (in both the lectures and the classroom/laboratory activities) will be used. Unifying themes will include mode of activation (blood-based, electrical, trauma/clinical), physiological underpinnings (from basic biophysics of the effects to molecular and energetic considerations), psychological (using all modalities on the same questions), and others. Activities will include design of a variety of experiments, exposure to a variety of software tools, tours and demonstrations of the techniques in action, and selected keynote lectures to exemplify particular experimental domains in which many of these techniques have been brought to bear on a specific problem.

More information here.

Sep 11, 2014 to Sep 13, 2014
(All day)
The Kresge Auditorium Building W16 48 Mass. Ave. (Rear) Cambridge, MA 02139

The Fourth Biennial Conference on Resting State / Brain Connectivity will bring together key researchers working on technical advances and methodological issues in imaging the brain’s functional connectome. In addition to the major topics of earlier years, the conference will include sessions on multi-modal imaging approaches to measure brain structure as well as brain function and include human imaging methods and animal models. Approximately one third of the conference will be dedicated to applications of brain connectivity methods and models in neurological and psychiatric disease. There will also be a special session dedicated to emerging technologies.

More information here.

Sep 29, 2014 to Oct 03, 2014
(All day)
Building 149, Charlestown Navy Yard, Charlestown, Mass.

Students in this course will receive a firm grounding in the fundamentals of fMRI. This will include the basic physics of MR imaging, the biology and biophysics of the hemodynamic responses to neural activity, data analysis (including both exploratory and statistical analyses), stimulus presentation and response recording in the context of high magnetic fields and electromagnetic pulses, and the design of perceptual and cognitive experiments. Some advanced topics (especially related to issues of connectivity) have been added.

A special emphasis of the course will be the design, implementation, and execution of perceptual and/or cognitive experiments by the participants. Participants will break into small groups to design their own fMRI experiments. Barring unforeseen problems, some of these experiments will be executed, and the resulting data analyzed, on the final day of the course. The core faculty is drawn from the staff of the Athinoula A. Martinos Center (of the Massachusetts General Hospital and Massachusetts Institute of Technology) and affiliated faculty from Harvard University, Boston University, McLean Hospital and other institutions.

More information here.