Director, Microscopy and Imaging Core Facility
Center for Biotechnology and Interdisciplinary Studies
Research Assistant Professor, Department of Biology
Rensselaer Polytechnic Institute

Education and Training:
1995, B.Sc. University of Manitoba, Genetics
2003, Ph.D. University of Manitoba, Developmental Cell Biology
2002-2007, Postdoctoral Associate, Wadsworth Center, Neuroscience

Career Highlights:
Chris Bjornsson earned his Ph.D. in developmental cell biology from the University of Manitoba, utilizing electrophysiology and immunofluorescence techniques to explore the role of proton and calcium fluxes in establishing developmental polarity during insect oogenesis.

Following his graduate studies, Bjornsson took postdoctoral position at the Wadsworth Center in Albany, NY. This research focused on characterizing and minimizing the brain’s reactive responses to neuroprosthetic devices, specifically the role of vascular damage in determining the extent of injury. He has taught histology and microtechnique at the Department of Zoology at U of M and at Albany Medical College in Albany, NY.

Research Areas:
My research is focused on characterizing the brain’s responses to implantation and stimulation of neural prosthetic devices. Neural prosthetic devices are currently being used in humans to treat neurological disorders including Parkinson’s disease, and to transform voluntary neural impulses into command signals that can control computers or robotic limbs to improve quality of life for people with severe motor disorders. These devices range in size from large 1.2mm-diameter deep-brain stimulating devices that plunge through 8cm of brain tissue to reach their targets, to silicon microelectrodes with a 15mmx120mm cross-section designed to be inserted into the cortex with a minimal footprint. Regardless of device size, cells of the nervous tissue and neurovasculature mount an immediate reactive response following device insertion, and develop a thick fibrous and cellular sheath in response to the chronic presence of implanted devices. This sheath impedes communication between neurons and device electrodes, and is the major cause of device failure after only a few months to a couple of years in the best cases. To address this problem, we are working to characterize the reactive response at the cellular and molecular level. This research will lead to new insights into strategies that will help minimize sheath formation and promote long-term integration of neural prosthetic devices.

In order to more fully characterize brain reactive responses, we have developed multilabel immunohistochemistry strategies in combination with spectral confocal imaging to maximize the amount of information that can be derived from single tissue sections. This approach has been indispensable for working with scant human tissue resected from patients with deep-brain stimulators, and for describing the morphology and interrelationships of multiple cell types within rat cortex. We have also helped develop automated image analysis software capable of analyzing complex multilabel 3-D images. In addition, we have developed novel live slice techniques to study the immediate effects of device insertion on tissue compression and vascular damage.

Current Projects:

• Investigating the importance of neurovascular damage in determining the severity of tissue responses and sheath formation.
• Developing minimally damaging device insertion techniques to reduce sheath formation.
• Improving multilabel immunohistochemistry and automated image analysis to fully describe the interrelationships among neurons, glia and vasculature in both normal and injured brain tissue.

Selected Publications:
ST Retterer, KL Smith, CS Bjornsson, JN Turner, MS Isaacson, W Shain (2008). Constant pressure fluid infusion into rat neocortex from implantable microfluidic devices. Journal of Neural Engineering in press.

Roysam B, Shain W, Barnes C, Mohler W, Bjornsson CS, Chen Y, Al-Kofahi Y, Narayanaswamy A (2008). FARSIGHT: A divide and conquer methodology for analyzing complex and dynamic biological microenvironments. In J Rittscher, R Machiraju, STC Wong (eds.) Microscopic Image Analysis for Life Science Applications. Artech House, Boston.

AR Cohen, C Bjornsson, S Temple, G Banker, B Roysam (2008). Automatic summarization of changes in biological image sequences using algorithmic information theory. IEEE Transactions on Pattern Analysis and Machine Intelligence in press.

CS Bjornsson, G Lin, YA Al-Kofahi, A Narayanaswamy, KL Smith, W Shain, B Roysam (2008). Associative Image Analysis: A method for quantification of 3D multi-parameter images of brain tissue. Journal of Neuroscience Methods 170(1): 165-78.

G Lin, MK Chawla, K Olson, CA Barnes, JF Guzowski, C Bjornsson, W Shain, B Roysam (2007). A multi-model approach to simultaneous segmentation and classification of heterogenous populations of cell nuclei in 3D confocal microscope images. Cytometry A 71(9): 724-36.

Bjornsson CS, Oh SJ, Al-Kofahi YA, Lim YJ, Smith KL, Turner JN, De S, Roysam B, Shain W, Kim SJ. Effects of insertion conditions on tissue strain and vascular damage during neuroprosthetic device insertion. Journal of Neural Engineering 3(3): 196-207, 2006.

Lin G, Bjornsson CS, Smith KL, Abdul-Karim MA, Turner JN, Shain W, Roysam B. Automated image analysis methods for 3-D quantification of the neurovascular unit from multichannel confocal microscope images. Cytometry A 66(1): 9-23, 2005.

Retterer S, Smith KL, Bjornsson CS, Neeves K, Spence A, Turner JN, Shain W, Isaacson M. Model neural prostheses with integrated microchannels: Treating the reactive responses to implantable devices. IEEE Trans. Biomed. Eng. 51(11): 2063-73, 2004.

Bjornsson CS, Huebner E. Extracellular hydrogen dynamics during oogenesis in Rhodnius prolixus ovarioles. J. Exp. Biol. 207(16): 2835-2844, 2004.

Szczurek EI, Bjornsson CS, Taylor CG. Dietary zinc deficiency and repletion modulate metallothionein immunolocalization and concentration in small intestine and liver of rats. J. Nutr. 131(8): 2132-2138, 2001.

Contact Information:
Chris Bjornsson
2149 Center for Biotechnology
(518) 276-3456
bjornc@rpi.edu