Biology subjects

Konofagou, E. E.

Publications and source records attributed to Konofagou, E. E..

4 recordsLinked to original sources

bioRxiv2024

Transcranial Functional Ultrasound Imaging Detects Focused Ultrasound Neuromodulation Induced Hemodynamic Changes in Mouse and Nonhuman Primate Brains In Vivo

BackgroundFocused ultrasound (FUS) is an emerging non-invasive technique for neuromodulation in the central nervous system (CNS). Functional ultrasound imaging (fUSI) leverages ultrafast Power Doppler Imaging (PDI) to detect changes in cerebral blood volume (CBV), which correlate well with neuronal activity and thus hold promise to monitor brain responses to FUS. ObjectiveInvestigate the immediate and short-term effects of transcranial FUS neuromodulation in the brain with fUSI by characterizing hemodynamic responses. MethodsWe designed a setup that aligns a FUS transducer with a linear array to allow immediate subsequent monitoring of the hemodynamic response with fUSI during and after FUS neuromodulation (FUS-fUSI) in lightly anesthetized mice. We investigated the effects of varying pressures and transducer positions on the hemodynamic responses. ResultsWe found that higher FUS pressures increase the size of the activated brain area, as well as the magnitude of change in CBV and could show that sham sonications did not produce hemodynamic responses. Unilateral sonications resulted in bilateral hemodynamic changes with a significantly stronger response on the ipsilateral side. FUS neuromodulation in mice with a cranial window showed distinct activation patterns that were frequency-dependent and different from the activation patterns observed in the transcranial model. ConclusionfUSI is hereby shown capable of transcranially monitoring online and short-term hemodynamic effects in the brain during and following FUS neuromodulation.

bioengineering↗

bioRxiv2023

Detection of Blood Volume Reduction and Vasoconstriction Following Focused Ultrasound Blood-Brain Barrier Opening Using Ultrasound Flow Imaging

Microbubble-mediated focused ultrasound (FUS) offers a non-invasive treatment for transient and localized blood-brain barrier (BBB) opening for drug delivery or immunostimulation. It is known that FUS-induced BBB opening is accompanied by blood flow changes, vasoconstriction, and vasodilation, as validated by optical microscopy through a cranial window. In this study, we introduce a novel method for quantifying vascular changes after FUS-induced BBB opening by employing ultrasound flow imaging in mice. We acquired pre-FUS and post-FUS ultrasound flow images with the same microbubble concentration in the brain. Contrast-enhanced power Doppler (CEPD) images and ultrasound localization microscopy images were obtained to evaluate changes in cerebral blood volume and vessel diameter at the sonicated region of the brain. Our findings demonstrate that FUS leads to a reduction in blood volume at the treated region, with vasoconstriction being more dominant than vasodilation. Furthermore, we show that transcranial CEPD can detect local blood reduction following FUS, which spatially coincides with the edema region identified in T2-weighted MRI. Our findings suggest that ultrasound flow imaging has the potential to serve as a cost-effective and immediate monitoring tool for evaluating the safety and efficacy of FUS-induced BBB opening.

bioengineering↗

bioRxiv2022

Focused ultrasound-mediated brain genome editing

Gene editing in the mammalian brain has been challenging because of the restricted transport imposed by the blood-brain barrier (BBB). Current approaches rely on local injection to bypass the BBB. However, such administration is highly invasive and not amenable to treating certain delicate regions of the brain. We demonstrate a safe and effective gene editing technique by using focused ultrasound (FUS) to transiently open the BBB for the transport of intravenously delivered CRISPR/Cas9 machinery to the brain.

bioengineering↗

bioRxiv2021

Long Term Study of Motivational and Cognitive Effects of Low-intensity Focused Ultrasound Neuromodulation in the Dorsal Striatum of Nonhuman Primates

Noninvasive brain stimulation using focused ultrasound (FUS) has many potential applications as a research and clinical tool, including incorporation into neural prosthetics for cognitive rehabilitation. To develop this technology, it is necessary to evaluate the safety and efficacy of FUS neuromodulation for specific brain targets and cognitive functions. It is also important to test whether repeated long-term application of FUS to deep brain targets improves or degrades behavioral and cognitive function. To this end, we investigated the effects of FUS in the dorsal striatum of nonhuman primates (NHP) performing a visual-motor decision-making task for small or large rewards. Over the course of 2 years, we performed 129 and 147 FUS applications, respectively, in two NHP. FUS (0.5 MHz @ 0.2 - 0.8 MPa) was applied to the putamen and caudate in both hemispheres to evaluate the effects on movement accuracy, motivation, decision accuracy, and response time. Sonicating the caudate or the putamen unilaterally resulted in modest but statistically significant improvements in motivation and decision accuracy, but at the cost of slower reaction times. The effects were dose (i.e., FUS pressure) and reward dependent. There was no effect on reaching accuracy, nor was there long-term behavioral impairment or neurological trauma evident on T1-weighted, T2-weighted, or susceptibility-weighted MRI scans. Sonication also resulted in significant changes in resting state functional connectivity between the caudate and multiple cortical regions. The results indicate that applying FUS to the dorsal striatum can positively impact the motivational and cognitive aspects of decision making. The capability of FUS to improve motivation and cognition in NHPs points to its therapeutic potential in treating a wide variety of human neural diseases, and warrants further development as a novel technique for non-invasive deep brain stimulation.

neuroscience↗