In pursuit of an optical peripheral nerve interface : targeting axons and evaluation of a genetically encoded indicator

Material Information

In pursuit of an optical peripheral nerve interface : targeting axons and evaluation of a genetically encoded indicator
Anderson, Hans Edgar
Place of Publication:
Denver, CO
University of Colorado Denver
Publication Date:

Thesis/Dissertation Information

Doctorate ( Doctor of philosophy)
Degree Grantor:
University of Colorado Denver
Degree Divisions:
Department of Bioengineering, CU Denver
Degree Disciplines:
Committee Chair:
Benninger, Richard
Committee Members:
Weir, Richard
Caldwell, John
Ribera, Angie


Limb loss is a problem that affects millions of Americans. While prosthetic limbs have been developed to restore function to these individuals, many of them fall short in returning people to their previous levels of function. One of the reasons that upper limb prosthesis prove insufficient, is the control interface, which often suffers from problems of selectivity, sensitivity and robustness. Current implantable electrode designs for peripheral nerves also may cause nerve damage due to their invasiveness. An optical neural interface overcomes some of these limitations, by allowing for read-out of neural activity from more inaccessible areas of the nerve cross section without penetrating the epineurium. Such an interface could also be used to read-in without the necessity of the higher currents required by extraneural electrodes. This work discusses two important components in such an interface, a genetically encoded fluorescent indicator of neural activity and means for achieving expression of that indicator in the axons of a peripheral nerve. Adenoassociated viral vectors (AAVs) provide a promising means of achieving expression of a genetically expressed indicator in motor axons targeted for read-out. To evaluate the effectiveness of these vectors, developed a fully automated counting system based on the freely available ImageJ image software to count the number of GFP labeled axons in immunohistochemically labeled transverse peripheral nerve sections was developed. This program was subsequently used in the determination of an optimal set of parameters for peripheral axonal expression, evaluating two routes of administration (intramuscular and intravenous), three promoters (cytomegalovirus (CMV) promoter, cytomegalovirus early enhancer/Chicken beta actin synthetic promoter (CAG), and the calmodulin kinase II (CaMKII) promoter), and six serotypes (1, 6, 7, 9, rh10, PHP.B). The CMV promoter, AAVrh10 for intravascular injections, and AAV1 and 6 for intramuscular injections showed promise for targeting peripheral axons. Finally, an AAV1 vector containing genetically encoded calcium indicator GCaMP6f was injected intramuscularly, and was used to report responses to electrically invoked action potentials in small fibers of peripheral nerve, ex vivo. Together these results suggest the biological feasibility of an optical neural interface with the peripheral nerve, and encourage further research of the topic.

Record Information

Source Institution:
University of Colorado Denver
Holding Location:
Auraria Library
Rights Management:
Copyright Hans Edgar Anderson. Permission granted to University of Colorado Denver to digitize and display this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.


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