Morteza Mohammadjavadi Best Poster Prize
Morteza Mohammadjavadi was awarded Best Poster at the Focused Ultrasound Neuromodulation Symposium in Oxford, England. An abstract of Morteza's poster is below.
Transcranial Focused Ultrasound Neuromodulation of the Thalamic Visual Pathway in a Large Animal Model
Morteza Mohammadjavadi, Pooja Gaur, Ningrui Li, Jan Kubanek, Yamil Saenz, Gary H. Glover,Gerald R. Popelka,, Anthony Norcia, Kim Butts Pauly
Ultrasound can be applied to the surface of the head and focused through the intact skull to target deep regions of the brain. The purpose of this study was to determine the effect of MR-guided transcranial focused ultrasound (tFUS) sonication of the lateral geniculate nucleus (LGN) on visual evoked potentials (VEPs).
Male sheep (N=6) were positioned in a 3T MRI scanner with an MR-compatible ultrasound transducer (ExAblate 2100, Insightec Ltd) affixed to the MR head coil. The LGN on one side was identified with T2- weighted MRI. MR acoustic radiation force imaging (MR-ARFI) was used to confirm a focal spot in a position away from LGN (Figure 1A). VEPs were elicited with 20 ms white-light flashes (binocular at 1 Hz) and recorded from subdermal EEG electrodes averaged over 300 presentations, up to 6 trials in each animal. tFUS pulses (PW 300 ms pulse duration, 50% duty cycle, 550kHz center frequency, at in situ estimated ISPTA values between 1 and 10 W/cm2) were applied to LGN for 40 min and then to the control location for an additional 60 min. Six control experiments were performed under identical conditions except with no LGN sonication. The VEP peak-to-peak amplitude (N70 and P100) was calculated for each trial. ISPTA was measured by hydrophone for each skull to investigate the effect of sonication intensity on the VEP amplitude suppression.
The VEP peak-to-peak amplitude at baseline was suppressed during tFUS sonication, gradually returning to baseline over 40 minutes after tFUS sonication (Figure 1B). The magnitude of the VEP suppression (about half shown in Figure 1B) was dependent on the sonication number and ISPTA (Figure 1C).
These results suggest that tFUS can be non-invasively delivered to the neural circuits of the deep structures in the brain to neuromodulate visual neural activity. Because the effects last for many minutes after sonication, care must be taken in interpreting studies with multiple sonications.