Skip to Content

Postbac Seminar Series: November 15, 2018

Series: Science Skills; Speaking

Nov 15, 2018

This event is recommended for: Postbacs.

Science isn't complete until the results have been shared with others, and talking about your results is one of the important ways of making them public. The Postbac Seminar Series provides a unique opportunity for two Postbacs each month to present their research to a diverse audience of their peers.  The atmosphere is relatively informal and non-threatening.  The series allows Postbacs who attend to learn about the different types of biomedical research being conducted at the NIH while meeting other postbacs.  Read more about the seminar series.

This month's presenters are:

Kelsey D. Csumitta (NIMH)

Title: Do Task-Negative responses reflect cortico-cortical competition from Task-Positive brain regions?

Summary: Functional brain networks showing task-induced increases, “Task-Positive”, and decreases, “Task-Negative”, inactivity are proposed to be intrinsically competitive. In the current study, we examine the relationship between these networks using fMRI during picture naming. If these functional networks are intrinsically competitive, then: 1) trial-level BOLD responses across Task-Positive and Task-Negative voxels should be anti-correlated, and 2) the correlation between the BOLD response and behavior (response time, RT) in Task-Positive and Task-Negative regions should exhibit opposite valence. In contrast to the competition proposal, we found predominantly positive correlations between Task-Negative regions and the rest of the brain. Although a few areas showed RT-BOLD slope reversals, the portion of variance related to behavior was small and did not detract much from the overall positive coupling. Taken together, these results argue against the proposal of inter-network competition, and instead, suggest independence and cooperation between these two systems.

Bio: Kelsey received her B.S. in Brain & Cognitive Sciences and B.A. in Psychology from the University of Rochester in 2017. Currently, Kelsey uses fMRI to study the nature of neural networks in Alex Martin’s lab in the NIMH Section on Cognitive Neuropsychology. In the future, Kelsey aims to pursue her Ph.D. in Clinical Psychology.


Priyankaa A. Bhatia (NIAID)

Title: Delivery and toxicity of dual-toxin constructs using the anthrax protective antigen pore

Summary: The anthrax toxin proteins PA and LF efficiently deliver polypeptides to the cytosol of cells. Both the non-catalytic portion of LF (LFn) and full-length LF can be fused genetically or chemically to bacterial toxin enzymes (effectors). These effector proteins unfold and translocate in a linear manner through a protein-conducting channel formed by PA. While often very potent in killing cells and in controlling tumor growth in mouse models, we asked whether greater efficacy could be achieved if several effectors were attached in tandem, creating a so-called "dual effector" agent. Sortase chemistry was used to create the fusions to cytolethal distending toxin subunit B (CdtB) and the Pseudomonas exotoxin A catalytic domain (PEIII). In general, the CdtB and PEIII effectors were more potent when attached to LFn than when attached to full-length LF. Analyses showed that both effectors acted on substrates in the cytosol, but less efficiently when attached to full-length LF.

Bio: Priyankaa received her B.S. in Biochemistry from Baylor University in 2017. Following graduation, she joined Dr. Stephen Leppla's lab at the NIAID where she works with anthrax toxins and constructs to target tumor cell growth and proliferation.


Annie-Lori Joseph (CC/RMD)

Title: Longitudinal neuropsychological, clinical, and imaging correlates of TBI

Summary: Traumatic brain injury (TBI) is a major public health problem in the United States, affecting approximately 2.8 million people annually. TBI is a multifaceted condition that evolves over time, and therefore it is important to understand the long-term effects of the injury. Our work assesses the neuropsychological, clinical, biological, and imaging correlates of mild, moderate, and severe non-penetrating TBI from 30 days to 5 years post-injury. Retrospective analyses of our data have shown that while our patients show cognitive improvement, wide-spread atrophy is present throughout the brain.

Bio: Annie is a post-baccalaureate IRTA with Dr. Leighton Chan’s traumatic brain injury team within the NIH Clinical Center. She received her B.A. in psychology from Wake Forest University in 2017. Annie’s research focuses on the longitudinal neuropsychological and clinical correlates of traumatic brain injury as well as the utility of certain cognitive assessments used with patients with TBI. Annie is hoping to continue her training in a graduate program in clinical neuropsychology in Fall 2019.