CNBC Brain Bag
Title: TBA
Presenter: Daniel Jimenez
Location: CNBC Conference room 115
Additional Information: Please RSVP to Joost Wagenaar (jbw14@pitt.edu) by Friday, October 3, and indicate if you require a vegetarian meal.
Abstract:

Competitive cell-specific survival of adult-born neurons in the mouse
olfactory bulb

Adult-born neurons (ABNs) in the olfactory bulb mature morphologically and
physiologically within four weeks after arriving at their target layer.
Survival of ABNs is reduced by manipulations, such as sensory deprivation,
but it is not known whether this is due to reduced activity in the new
neurons or in existing cells in the network. We hypothesized that adult-born
neurons survive through a competitive process in which a new neuron's
activity, relative to the activity of other neurons in the network, is
critical for the survival of adult-born neurons. To test this hypothesis we
injected a lentivirus that resulted in siRNA-mediated reduction of sodium
channel expression in a labeled population of ABNs. The effectiveness of the
knockdown was confirmed through immunohistochemistry and electrophysiolgical
recordings. The siRNA infected ABNs showed a drastically lower survival when
compared to a control population of control virus-infected cells in the
opposite hemisphere. In addition, the dendritic complexity and spine density
was reduced in siRNA expressing ABNs. Ongoing experiments will examine the
integration of control and knockdown ABNs in a circuit in which activity is
reduced by unilateral nares occlusion. This will allow us to relate the
effect of a particular cells activity and the effect of network level
activity to the survival of ABNs in the mouse olfactory bulb.

Title: Imaging function and chemistry using ultrahigh magnetic field
Presenter: Kamil Ugurbil, Ph.D.
Location: CHP MT, 3850/3851 Radiology Conference Room

Abstract: In the last decade and a half, imaging of cellular processes in vivo has been identified as an indispensible capability for biomedical research. Today, numerous different technologies are employed in pursuit of imaging processes such as organ function, intracellular chemistry, tissue perfusion, oxygen utilization, gene expression, and enzyme activity in intact animals and humans. In this effort, magnetic resonance imaging (MRI) has evolved as a powerful tool. MRI has proven to be rich in information content but has inherently relatively poor detection sensitivity, which imposes a fundamental limitation on this methodology. Starting in the early nineties, we have pursued higher magnetic fields to overcome such limitations. Higher magnetic fields, however, pose numerous serious challenges for imaging biological objects the size of the human head and human torso. However, we have demonstrated that with appropriate engineering and methodological solutions, high and ultrahigh fields (7 and 9.4 Tesla in human and animal model studies) provide numerous advantages that include improved signal-to-noise (SNR) ratio and, in many applications, significantly improved anatomical and functional contrast. One of the unique contrast mechanisms that improve with magnetic field is susceptibility contrast. This contrast provides the mechanism for functional neuroimaging with magnetic resonance (fMRI). Most recently, we have demonstrated that functional imaging at the level elementary computational units such as cortical columns is feasible even in the human brain using ultrahigh magnetic fields. The same methods that enabled this accomplishment also led to the first time imaging of Alzheimer’s plagues in genetically engineered AD mice. These functional maps can be supplemented by measurements of processes such as oxygen consumption to investigate the coupling between function and bioenergetics. Expanding these boundaries to imaging of processes such as gene expression and enzyme activity ultimately will require the use of ultrahigh fields coupled with the use functionalized contrast agents. While this is proving to be a difficult path, preliminary results demonstrate the presence of possible solutions.
 

SCIENCE 2008 - Klaus Hofmann Lecture
Title: Two Views of Brain Function
Presenter: Marcus E. Raichle, MD
Location: 7TH Floor Alumni Hall