Events

Apr 29, 2015
12:00 PM
Seminar room 2204 149 13th St., Charlestown Navy Yard

Brain glial imaging in chronic pain

Microglia and astrocytes respond to pathological events in the central nervous system, such as strokes, trauma or neurodegenerative diseases, by undergoing a series of cellular responses collectively known as 'glial activation'. As such, glial activation may be a used as a biomarker for neuropathology, as well as a therapeutic target for many conditions. In this talk, I will present a study in which the novel technology of integrated positron emission tomography-magnetic resonance imaging and the recently-developed radioligand [11C]PBR28 was used to show increased brain levels of the translocator protein (TSPO), a marker of glial activation, in patients with chronic low back pain (cLBP). In cLBP patients we observed a significant [11C]PBR28 signal increase in multiple brain regions, including thalamus and the putative somatosensory representations of the lumbar spine and leg. Despite the signal increase in patients, the thalamic levels of TSPO were negatively correlated with clinical pain and levels of circulating proinflammatory cytokines, suggesting that TSPO expression exerts pain-protective/anti-inflammatory effects in humans, by limiting the extent of glial responses. Given the putative role of activated glia in the establishment and or maintenance of persistent pain, the present findings offer clinical implications that may serve to guide future studies of the pathophysiology and management of a variety of persistent pain conditions.

May 06, 2015
12:00 PM
Seminar room 2204 149 13th St., Charlestown Navy Yard

Polarized light microscopy of myeloarchitecture and spatial orientation of fiber tracts in human and non-human brains

Using Polarized Light Imaging (PLI), the birefringence of neuronal tissue, particularly of myelinated nerve fibres enables - without any staining procedures - the visualization of single nerve fibres and fibre tracts at an in-plane resolution of 1.3 mm in whole brain sections. The spatial orientation of fibres and fibre tracts can be calculated using Jones Calculus. We have studied human ex vivo brains, and those of vervet monkeys, rats and mice to demonstrate the myeloarchitecture of nerve fibres within the cortical ribbon and the course of fibre tracts in the white matter.

After an introduction to the method, examples of the spatial orientation of fibre tracts in 60-70 mm thick serial sections through human, vervet monkey, rat and mouse brains will be demonstrated. An example of a first 3D-reconstruction of all fibre tracts in a rat brain will also be shown. PLI also allows the visualization of fibre tracts selected by their spatial orientation (“spot light imaging”). Furthermore, the excellent contrast of all fibres within the cortical ribbon provides a new approach to myeloarchitectonic mapping of the cerebral cortex. Finally, PLI may serve as an independent method for validation of data based on diffusion weighted imaging. In conclusion, PLI provides an unprecedented spatial resolution of the anatomical ground truth of fibre tracts and reveals a hitherto unknown complexity of structural connectivity.