Graduate Student Seminar Series Continues April 4

Three Ph.D. candidates will discuss their research at the Beckman Institute’s Graduate Student Seminar at noon Wednesday, April 4, in Room 1005. The presenters: Kelsey Dzwilewski and Anthony Fan, both in the Cellular and Molecular Foundations of Intelligent Behavior Group; and Matthew Moore, a Beckman Institute Graduate Fellow in the Social and Emotional Dimensions of Well-being Group. Lunch will be provided.

“Impacts of Prenatal Exposure to Endocrine Disrupting Chemicals on Early Cognitive Development”

Kelsey Dzwilewski, neuroscience, Cellular and Molecular Foundations of Intelligent Behavior Group

Endocrine disrupting chemicals (EDCs) are a class of chemicals shown to affect hormone systems in both animal models and human studies. Their widespread use in everyday consumer products, including personal care products, plastics, and food and drink containers, has led to ubiquitous exposure to multiple EDCs among pregnant women. Due to the importance of the endocrine system to central nervous system development, this could lead to impairments in cognitive development. Our goal is to assess potential impacts of prenatal exposure to a number of these chemicals on early building blocks of cognition in infants, including recognition memory, information processing speed, and attention. Preliminary findings and future directions for this ongoing project will be presented.

“A Tensed Pathway to Vesicle Clustering”

Anthony Fan, mechanical science and engineering, Cellular and Molecular Foundations of Intelligent Behavior Group

Synaptic vesicles cluster at the presynaptic terminal to facilitate neurotransmitter release when an action potential arrives. It has been suggested that this clustering of vesicles is heavily influenced by mechanical tension. Recently, evidence has shown that there is a cortical network of actin, among other proteins, along the conduit of an axon; its contractility, powered by the acto-myosin machinery, gives rise to the axon’s intrinsic tension. Here, we employed two strains of transgenic drosophila embryos of stage 16 that had green fluorescence protein tagged to synaptic vesicles and red fluorescence protein tagged to F-actin respectively in neurons. Embryos were prepared such that intact single axons could be visualized in vivo. Using a time-lapse confocal setup, we observed concurrent F-actin disassembly and vesicle declustering when axonal tension was disrupted by chemical treatment. Furthermore, we showed that vesicle declustering was a direct consequence of the loss of axonal tension by partially treating a proximal segment of the axons away from the synapse with a microfluidic device. Results collectively suggest that axonal tension sustains an F-actin rich scaffold at the presynaptic terminal allowing vesicles to cluster.

“Simultaneous Multi-method Brain Imaging Investigation of Human Brain Function: Evidence for a Proof of Concept”

Matthew Moore, psychology, Beckman Institute Graduate Fellow, Social and Emotional Dimensions of Well-being Group

Although brain imaging methodologies have progressed dramatically over the past decades, current techniques show important limitations in either spatial or temporal domains. Consistent with these limitations, the link between spatial (where) and temporal (when) aspects of the neural correlates of most psychological phenomena remains unclear. Multimodal imaging approaches may overcome such limitations by capitalizing on the individual strengths of different brain imaging modalities. By overcoming the methodological challenges posed by simultaneous recordings, the present investigation provides proof-of-concept evidence for a novel approach using three complementary imaging modalities: functional magnetic resonance imaging (fMRI), electroencephalography/event-related potentials (EEG/ERP), and event-related optical signals (EROS). Using a task that taps into both cognitive and emotional aspects of processing, this approach demonstrates the feasibility of capturing converging and complementary measures of brain function that are not currently attainable using traditional uni-modal or other multimodal approaches. More specifically, results show that frontal dorsal-ventral dissociations are effectively captured using fMRI, and similar dissociations are captured using EROS but in time windows similar to ERP responses, while the ERPs are captured at posterior locations. These results point to ways in which distinct brain imaging methodologies can be used simultaneously to investigate spatial and temporal aspects of psychophysiological phenomena.