Events

Jan 25, 2017
12:30 PM

 

Abstract:

Thanks to large scale neuroimaging initiatives like the human connectome project, we now have a wiring diagram of the healthy human brain.  This wiring diagram helps us see how brain regions are connected, both structurally and functionally.  An important question is how this wiring diagram, based on healthy brains, can be used to help patients with brain disease.  Here, I provide two examples.  First, I show how this wiring diagram can be used to understand and localize symptoms caused by focal brain lesions.  Because symptoms can come from brain regions connected to the lesion location, not just the lesion location itself, a map of human brain connectivity is critical for linking symptoms to specific brain regions.  I will show application of this concept towards understanding lesion-induced hallucinations, delusions, involuntary movements, and disruptions in consciousness. Second, I will show how the normative human connectome can be used to better understand and guide brain stimulation therapies.  Because therapeutic benefit from brain stimulation can come from connected brain areas, not just the site of stimulation, a map of human brain connectivity can help identify the ideal spot to stimulate.  I will show application of this concept for deep brain stimulation for Parkinson’s disease and transcranial magnetic stimulation for depression.

 

About the Speaker:

Dr. Fox is the Director of the Laboratory for Brain Network Imaging and Modulation.  His research focuses on the development of new and improved treatments for neuropsychiatric disease based on understanding brain networks and the effects of brain stimulation. He is a recognized expert in the use of brain network imaging such as resting state functional connectivity MRI and a leader in applying these techniques towards improved brain stimulation therapies. He is the author of numerous highly cited articles in the fields of brain imaging and brain stimulation, teaches courses on these topics at the Martino’s Center for Biomedical Imaging at MGH and the Berenson-Allen Center for Noninvasive Brain Stimulation at BIDMC, holds multiple patents, and has won several awards for his work.

Jan 26, 2017
11:00 AM
Building 75, room 1103

Abstract:

Calibrated functional MRI was developed to tease apart the hemodynamic and metabolic contributions to the blood oxygenation level-dependent (BOLD) signal using simultaneous measurements of the BOLD signal and cerebral blood flow. While calibrated fMRI has substantially improved our ability to image and understand aspects of brain physiology, it has not been widely adopted due to the need for specialized gas delivery equipment and biophysical confounds associated with the calibration measurements. One such confound is the magnetic susceptibility of dissolved oxygen, which, like deoxyhemoglobin, is paramagnetic. In this talk, I will present work on modelling and measuring the susceptibility and relaxation rates of dissolved oxygen in blood and what impact they have on the hyperoxic BOLD signal and calibration. I will also discuss recent efforts towards improving the accuracy of gas-free BOLD calibration. This work could greatly increase the appeal of calibrated fMRI by eliminating the gas challenge completely. In all, I hope these studies underscore the role that analytical modelling and simulations can play in improving our understanding of the biophysics of the BOLD signal and in guiding imaging strategies to probe brain physiology.