Masters Applied Projects

Project 9

Exploration of Cerebral Vascular Reaction to both Monopolar and Bipolar Stimulation at Varying Depths During Implantation Towards Subthalamic Nucleus (STN) Within Rodents

Student:

Sarah Soaf

Mentors:

Dr. Bradley Greger - SBHSE

Dr. Eric Maass - SBHSE

Dr. Jitendran Muthuswamy - SBHSE

YouTube Link:
View the video link below before joining the zoom meeting

Zoom link:

https://asu.zoom.us/j/88481934800

Abstract:

In deep brain stimulation (DBS), accurate positioning of the stimulating electrode within the dorsolateral motor region of the sub-thalamic nuclei (STN) provides the best motor symptom control for patients with Parkinson’s disease (PD). Current imaging methods are useful but do not provide any functional feedback in this challenging task. This study explored cerebral blood flow as a feedback variable to help optimize electrode positioning and possibly confirm location with patient fully anesthetized. We hypothesize that the cerebrovascular response in the ipsi-lateral primary motor cortex (PMC) will be strongest in response to stimulation of STN. Sprague Dawley (SD) rats, both male and female were surgically implanted with monopolar or bipolar electrodes in the STN and stimulated with biphasic (cathodic first) pulses of 200-450 µA, 90 µs duration at 130 Hz. Cerebral blood flow was recorded with the use of a laser doppler flowmetry probe placed superficially on the PMC as the stimulating electrode was moved in 0.1 mm increments towards the STN in acute experiments. Unipolar stimulation of STN at ~ 8 mm depth, showed a peak blood flow response that decreased gently as the electrode was moved away from STN. However, we did not see a similar tuning curve with bipolar stimulation. The results from this study will help to develop understanding of the cerebrovascular effects which occur due to DBS of the STN.