Current Research and Scholarly Interests


Invasive and Non-Invasive Neuromodulation, Drug Delivery, Neurosurgical Outcomes

Current Clinical Interests


  • Critical Care
  • Neurosurgery

Lab Affiliations


All Publications


  • Deep Brain Stimulation for Chronic Cluster Headache: A Review NEUROMODULATION Vyas, D. B., Ho, A. L., Dadey, D. Y., Pendharkar, A. V., Sussman, E. S., Cowan, R., Halpern, C. H. 2019; 22 (4): 388–97

    View details for DOI 10.1111/ner.12869

    View details for Web of Science ID 000471831000003

  • Socioeconomic Predictors of Pituitary Surgery CUREUS Deb, S., Vyas, D. B., Pendharkar, A., Rezaii, P. G., Schoen, M. K., Desai, K., Gephart, M. H., Desai, A. 2019; 11 (1)
  • Hand function, not proximity, biases visuotactile integration later in object processing: An ERP study. Consciousness and cognition Vyas, D. B., Garza, J. P., Reed, C. L. 2019; 69: 26–35

    Abstract

    Behavioral studies document a functional hand proximity effect: objects near the palm, but not the back of the hand, affect visual processing. Although visuotactile bimodal neurons integrate visual and haptic inputs, their receptive fields in monkey cortex encompass the whole hand, not just the palm. Using ERPs, we investigated whether hand function influenced the topology of integrated space around the hand. In a visual detection paradigm, target and non-target stimuli appeared equidistantly in front or in back of the hand. Equivalent N1 amplitudes were found for both conditions. P3 target versus non-target amplitude differences were greater for palm conditions. Hand proximity biased processing of visual targets equidistant from the hand early in processing. However, hand function biases emerged later when targets were selected for potential action. Thus, early hand proximity effects on object processing depend on sensory-reliant neural responses, whereas later multisensory integration depend more on the hand's functional expertise.

    View details for PubMedID 30685514

  • Noninvasive Ultrasonic Drug Uncaging Maps Whole-Brain Functional Networks. Neuron Wang, J. B., Aryal, M., Zhong, Q., Vyas, D. B., Airan, R. D. 2018; 100 (3): 728

    Abstract

    Being able to noninvasively modulate brain activity, where and when an experimenter desires, with an immediate path toward human translation is a long-standing goal for neuroscience. To enable robust perturbation of brain activity while leveraging the ability of focused ultrasound to deliver energy to any point of the brain noninvasively, we have developed biocompatible and clinically translatable nanoparticles that allow ultrasound-induced uncaging of neuromodulatory drugs. Utilizing the anesthetic propofol, together with electrophysiological and imaging assays, we show that the neuromodulatory effect of ultrasonic drug uncaging is limited spatially and temporally by the size of the ultrasound focus, the sonication timing, and the pharmacokinetics of the uncaged drug. Moreover, we see secondary effects in brain regions anatomically distinct from and functionally connected to the sonicated region, indicating that ultrasonic drug uncaging could noninvasively map the changes in functional network connectivity associated with pharmacologic action at a particular brain target.

    View details for PubMedID 30408444

  • Feeling but not seeing the hand: Occluded hand position reduces the hand proximity effect in ERPs CONSCIOUSNESS AND COGNITION Reed, C. L., Garza, J. P., Vyas, D. B. 2018; 64: 154–63

    Abstract

    The hand proximity effect (nearby hands influence visual processing) reflects the integration of vision and proprioception for upcoming action; it is reduced when hand position is occluded. In an ERP study, we investigate whether hand proximity, without vision of the hand, accentuates the processing of stimuli requiring actions (targets) early (N1) and later (P3) in processing. In a go/no-go paradigm, participants viewed stimuli between two panels with hands placed near or far from stimuli. Occlusion of the hand eliminated near-hand target vs. non-target differentiation of the N1; amplification of near-hand target amplitudes emerged at the P3. Visual hand location appears necessary to draw visual attention to intended-action objects to integrate body and visual information early in processing. The integration of visual stimulus information and hand position from proprioception appears later in processing, indicating greater reliance on cognitive systems for discriminating the task-relevance of a stimulus.

    View details for PubMedID 29735213

  • The Search for Meaning. Academic medicine : journal of the Association of American Medical Colleges Brewster, R., Vyas, D. 2018; 93 (6): 823

    View details for PubMedID 29538112

  • Radiosurgery for Trigeminal Neuralgia Effective Techniques for Managing Trigeminal Neuralgia Vyas, D. B., Kim, L. H., Ho, A., Sussman, E. S., Pendharkar, A. V., Chang, S. IGI Global. 2018: 187–215
  • Holistic processing for bodies and body parts: New evidence from stereoscopic depth manipulations PSYCHONOMIC BULLETIN & REVIEW Harris, A., Vyas, D. B., Reed, C. L. 2016; 23 (5): 1513–19

    Abstract

    Although holistic processing has been documented extensively for upright faces, it is unclear whether it occurs for other visual categories with more extensive substructure, such as body postures. Like faces, body postures have high social relevance, but they differ in having fine-grain organization not only of basic parts (e.g., arm) but also subparts (e.g., elbow, wrist, hand). To compare holistic processing for whole bodies and body parts, we employed a novel stereoscopic depth manipulation that creates either the percept of a whole body occluded by a set of bars, or of segments of a body floating in front of a background. Despite sharing low-level visual properties, only the stimulus perceived as being behind bars should be holistically "filled in" via amodal completion. In two experiments, we tested for better identification of individual body parts within the context of a body versus in isolation. Consistent with previous findings, recognition of body parts was better in the context of a whole body when the body was amodally completed behind occluders. However, when the same bodies were perceived as floating in strips, performance was significantly worse, and not significantly different, from that for amodally completed parts, supporting holistic processing of body postures. Intriguingly, performance was worst for parts in the frontal depth condition, suggesting that these effects may extend from gross body organization to a more local level. These results provide suggestive evidence that holistic representations may not be "all-or-none," but rather also operate on body regions of more limited spatial extent.

    View details for PubMedID 27001251