“Astrocytes in the Hippocampal Dentate Gyrus Exhibit Diurnal Morphological and Coupling Heterogeneity via Label-free Imaging”
Ghazal Naseri Kouzehgarani, a Ph.D. student in the Neuroscience Program, Beckman Institute Graduate Fellow, and a member of the Neurotechnology for Memory and Cognition Group
Complex brain functions, including learning and memory, arise in part from the modulatory role of astrocytes on neuronal circuits. We have previously demonstrated a significant diurnal difference in astrocyte organization in key regions of the brain, including the dentate gyrus (DG). Functionally, the DG exhibits differences in acquisition of long-term potentiation (LTP) between day and night. We hypothesize that the dynamic nature of these astrocyte networks plays an important role in the functional circuitry of hippocampal learning and memory, specifically in the DG. Standard techniques such as differential interference contrast (DIC) have been unable to correlate astrocyte electrophysiological and coupling properties with the extensive astrocyte branching morphology. Gradient light interference microscopy (GLIM), a quantitative phase imaging label-free technique, allows for imaging of substantially thicker specimens than previously achieved with standard fluorescence-labeling techniques. This enables us to obtain dry mass values of the cell bodies and processes as well as total cell volume measurements that can then be used to quantify the difference in astrocyte branching complexity over the day-night cycle. Our preliminary results found distinct diurnal coupling properties of astrocyte populations within the rat hippocampal DG. Our data suggest that the number of coupled astrocytes is significantly higher during the night than the daytime. These coupled cells display linear voltage-current profiles with very low resistances (< 20 MΩ) at both time points. Additionally, we have found the hippocampal astrocytes of the ML/DG display greater volume and dry mass during nighttime, the active phase of the nocturnal animal. Utilizing emerging technology of label-free imaging in brain slices along with electrophysiological measurements will allow us to advance our knowledge of the role of astrocytic networks in regulating neuronal circuitry important in learning and memory.
"Association of Maternal Prenatal Stress With Measures of Cognition in 4 1/2 month-old Infants"
Francheska Merced-Nieves, Ph.D. student in the Neuroscience Program, an NIH Interdisciplinary Environmental Toxicology Predoctoral Fellow, and a member of the Cellular and Molecular Foundations of Intelligent Behavior Group
Recent literature has shown that maternal exposures to both chemical and non-chemical stressors during gestation are risk factors for adverse neurodevelopment. Maternal psychological stress is highly prevalent in the U.S., with up to 25 percent of women experiencing clinically significant stress. However, there is little research looking at its effect on the offspring’s neurodevelopment and even less at sexually dimorphic aspects of neurodevelopment. The Illinois Kids Development Study (IKIDS) aims to assess potential impacts of prenatal exposure to a number of environmental factors on early building blocks of cognition in infants. Our study takes advantage of research in developmental psychology, which showed that infant looking behaviors can be used as reliable and stable measures of basic cognitive processes. This presentation will focus on the association of prenatal stress with understanding of a physical reasoning task at 4-5 months of age.
“Improving Contrast with Phase Shifting Interferometry”
Mikhail E. Kandel, Ph.D. student in electrical and computer engineering, Miniature Brain Machinery Graduate Fellow, member of the Neurotechnology for Memory and Cognition Group
Quantitative phase imaging (QPI) yields the spatial phase map of the object’s scattering potential. QPI has enabled unprecedented label-free studies in biomedicine, ranging from cell dynamics and growth to cancer diagnosis and prognosis. Recent advances have focused on phase retrieval from turbid samples toward in vivo applications. The field is currently transitioning from technology-driven to application-driven research with the focus shifting from users with an engineering background to users with a biomedical background. Aligned with these efforts, I present our preliminary studies using high-throughput user-friendly QPI technology.