Danon disease, a form of cardiomyopathy, results in deficient blood flow due to the weakening of heart muscles and can lead to a shortened lifespan. In collaboration with the Song lab at the University of Colorado, we aim to better understand the differences in contractile function between healthy cardiomyocytes and those from individuals with Danon disease. The Song lab obtained primary adult cells from two control groups—healthy individuals without cardiac problems—and three diseased groups—people suffering from Danon disease. The patient cells were used to generate induced pluripotent stem cells (iPSC), from which they derived cardiomyocytes that possess genetic information of the original donor. The Sniadecki lab has the technology to make micropost substrates from polydimethylsiloxane (PDMS), using a soft lithography process. The iPSC-cardiomyocytes were seeded onto the microposts. As the cardiomyocytes contract on the microposts, each post under the cell deflects. Videos were taken at the tips of the microposts underneath the beating cells, to record the post deflection over time. A still image was taken at the bottom of the microposts in order to determine the relative deflection of each post. From the deflection of the posts, we were able to measure contractile forces produced by the iPSC-cardiomyocytes using simple beam bending theory. For this experiment, we used microposts with following dimensions: height = 4.14 μm, diameter = 1.75 μm, and center-to-center spacing of 6 μm. These dimensions gave each post a stiffness = 56 nN/μm, which was used to calculate the force. We hypothesized that the diseased cells will produce lower contractile forces than the control cells. The results produced supported our hypothesis. We hope this study contributes to the effect of Danon disease on the contractile function of cardiomyocytes. Further, this work would exemplify a methodology to investigate cardiac disease modeling and treatments.

 The African and Afro-Caribbean Women’s Health Study (AACWHS) focuses on perceived discrimination and stress among African and Afro-Caribbean U.S. immigrants. The overall aim of the study is to gain a better understanding of how perceived discrimination triggers a physiological response that leads to negative health effects, in the short term and over the life-course. The hypothesis is that the longer participants have lived in the United States, the more likely they are to ascribe daily hassles to discrimination, correlated to negative health effects. We are interested in collecting quantitative data from surveys utilizing scales including the Everyday Discrimination Scale and Phinney’s Multigroup Ethnic Identity Measure (1992), and biometrics to assess allostatic load. The survey will assess perceived discrimination in the form of attribution of everyday hassles, and connection to one’s own ethnic group here in the U.S. The study seeks to determine why health profiles differ between foreign-born and native-born peoples, and identify how immigrants’ appraisals of daily experiences may serve as a protective factor that mediates the impacts of discrimination on health. The data will provide a better understanding of the role that perceived discrimination plays in stress level, while examining the biological pathways that link perceived discrimination and chronic stress. Expected results include data demonstrating an increased perception of discriminatory events in relation to years spent in the U.S., and indications via biomarkers of chronic stress in adults experiencing discrimination.

Transcranial magnetic stimulation (TMS) is a method of noninvasively and reversibly influencing brain activity through the generation of brief magnetic fields. Utilizing this approach, we investigate the role of the semantic representation of objects in the dorsal portion of the premotor cortex (PMd). The ventral portion of the premotor cortex (PMv) has been known to be involved in the representation of manipulable objects, such as tools. Conversely, we provide evidence that stimulation of PMd facilitates access to foot-related objects (such as sandals or slippers) by observing decreased decision times in a categorization task when PMd is stimulated at 110% of motor threshold. Within this task, subjects are shown a category, either “object” or “animal”, and asked to select which of two options match the provided category. These findings also provide support for the notion that the human premotor cortex has a topological organization and that part of the organization of sematic knowledge for objects depends on the modality with which they are interacted.

In the field of cognitive psychology, multiple studies have shown that humans seem able to recall a large amount of information with great detail. Thus, scientists are particularly interested in understanding the exact mechanisms by which memories are encoded in the human brain. Current models of semantic knowledge origin can be classified into two families: semantic network models and embodied cognition models. My experiment provides a way to distinguish between these two models by examining which type of interferences (semantic vs. sensorimoter) has a larger effect on semantic memory retrieval. Thirty participants were asked to perform a computer task, during which they chose the picture of an object that matched the target word from an array of objects that containd different distractors. There are three conditions, corresponding to the different types of distractor objects: unrelated distractors, sensorimotor distractors, and semantically associated distractors. Greater interference from distractors reflects greater similarity in concept representation, and thus results in slower response times. Our results show that the mean reaction time of semantically associated distractor condition is the largest. The mean reaction time of unrelated distractor (control) condition is the second largest and that of sensorimotor distractor condition is the smallest. The results support the semantic network models and indicate the facilitation of sensorimotor related objects. The results from these comparisons can not only provide us with a general idea of how the embodied cognition model and semantic network models differ from each other, but also provide us with potential applications to everyday life. First, for example, knowing the patterns from which people build concepts in mind inspires people to create memorization strategies, leading to the improvement of memorization. Second, as a growing area in cognitive psychology, embodied cognition is related to not only memory, but also emotion, perception, and language, etc.    

Phosphenes are temporary visual percepts which can be elicited via transcranial magnetic stimulation (TMS) of the visual cortex. Often described as flashes or blobs of light, phosphenes usually occupy a small subset of the visual field and can be consciously perceived and described by a human subject. In order to investigate the relationship between phosphene characteristics and the methods in which they are elicited, subjects were asked to draw the phosphenes they perceive in response to different stimulation intensities, locations, and orientations. This information was then used for direct brain-to-brain communication of simple images. Functional magnetic resonance imaging (fMRI) was utilized to decode information from the brain of one human (“the sender”) and TMS was used to encode that information into the brain of another human (“the receiver”). Namely, the image that the sender viewed was determined by monitoring oxygenated blood flow patterns in the brain and transmitted directly to the brain of the receiver. The receiver “saw” the image viewed by the sender through TMS-induced phosphenes which were elicited by stimulating with parameters determined during the mapping stage. This brain-to-brain interface allows for the successful transmission of complex visual information directly from one human brain to another and does so through noninvasive methods.