Graduate Student Seminar on Oct. 30

Andrew Bower (Bioimaging), Windy Santa Cruz (Autonomous Materials Systems), and John Walker (Cognitive Neuroscience) will present on Oct. 30 at noon in Beckman Room 1005. Lunch will be served.

Andrew Bower

Integrated Optical Coherence and Multiphoton Microscopy for Biomedical Applications
Optical imaging techniques such as optical coherence microscopy (OCM) and multiphoton microscopy (MPM) are emerging high resolution, noninvasive biomedical imaging modalities. The integration of these modalities into a single platform allows for simultaneous acquisition of both structural and functional information. By combining OCM, based on the endogenous light scattering properties of the sample, and MPM, based on fluorescence of endogenous or exogenous markers, this microscope provides complementary image contrast mechanisms useful in extracting more necessary information from the sample. Applications such as in vivo skin imaging and engineered tissue imaging have been studied and long-term tracking of cell populations and has been achieved in vivo. Currently, investigations of in vivo grafting of engineered skin tissues are being studied. By exploring the interactions between cells and these engineered tissues in vivo, these studies will ultimately help establish conditions necessary to produce more physiologically-relevant skin substitutes.

Windy Santa Cruz

Material Regeneration by Two-Stage Chemical Resins
Autonomous self-healing polymers repair damage without the use of external energy or human intervention. For this reason, self-healing polymers are ideal for complex aerospace materials that are expensive and difficult to repair/replace. While many healing strategies focus on micro-sized damage, regeneration of large volumes requires new concepts and approaches. We address the challenges arising from gravity and surface tension using a two-stage chemical resin. Beginning from a stable low-viscosity solution, the resin undergoes a rapid acid-catalyzed gelation followed by bulk polymerization of monomer solvent. The gel stage achieves the growth and restorative properties allowing the resin to span gaps in excess of 7.5 mm. The polymer stage completes the regenerative process by recovering the mechanical properties of the virgin substrate. We can tailor to multiple damage geometries by careful timing of these chemical transformations. This two-staged approach defines a new type of autonomic chemistry and further expands the healing capacity of microvascular materials.

John Walker

Cortical Reactivation of Related Stimuli and Its Association with Hippocampal Volume
Memory theories suggest that successful retrieval may depend on the ability to reactivate an item in the presence of related information.  Research has shown that the presentation (or “preview”) of an item from a previously studied pair immediately prior to a test display facilitates the identification of the whole pair. It has been suggested that this facilitation occurs because the preview of the item may induce the reactivation of the representation of the related item. In the first use of the brain imaging technique the event related optical signal (EROS) for the study of long-term memory, we examined relational or associative aspects of memory. We found that a brain region known to be involved in face processing (region STS) was active not only when viewing faces during the study phase but also when viewing scenes at test that, through prior learning, were associated with specific faces. In a second study we found that this relational reactivation was positively correlated with hippocampal size (an area associated with declarative memory), which in turn was predictive of behavioral performance. These findings reveal cortical substrates of the reactivation of relational memories and its association with the hippocampus.