Circuit Diagrams

Abstract During Phase I, we will test the feasibility of developing a magnetographic camera technology as a new tool in neuroscience to facilitate the detailed analysis of electrical currents in diverse neuronal circuits. Instead of photographic images, the camera will produce single-shot images of the magnetic fields from in vivo samples of interest, such as a patch of the grey matter in the cerebral cortex or the dorsal hippocampus.

SF424 – Project Summary Understanding how the brain generates certain behaviors requires an understanding of the function of individual neurons in dynamical neural circuits. Currently, there are few technologies available however that allow researchers to record both the activity within a brain region, and between brain regions in the brains of awake, behaving animals. Recent advances in microelectrode fabrication are now enabling recordings of recording hundreds to thousands of neurons simultaneously across brain regions that will lead to functional analyses of dynamical neural circuits.

Project Summary/Abstract It is the dream of researcher's and clinician's to have available a low cost, portable MRI scanner for brain neuroimaging. However, such a low cost MRI system requires a small bore MRI magnet. Unfortunately, in the case of conventional MRI systems, small bore magnets have a usable homogeneous magnetic field Diameter Spherical Volume (DSV) that is much smaller than the size of the human brain.

Project Summary Autism Spectrum Disorder (ASD) is a broad diagnosis for a disorder characterized by symptoms affecting repetitive behavior, social communication, and cognitive ability. 1 in 68 children in the US is affected with ASD (Centers for Disease Control and Prevention, 2017) and the likelihood that a child will be affected with ASD is 10 times higher if they have a sibling with ASD. Traditionally, diagnosis occurs most frequently between age 3 to 6 and severe ASD can be diagnosed as early as 18 months.

Transcranial magnetic stimulation (TMS) is a noninvasive technique used for neuroscience research and treatment of psychiatric and neurological disorders. During TMS, a current-carrying coil placed on the scalp induces an electric field that modulates targeted neuronal circuits. Computational simulations of the electric field (E-field) induced by TMS are increasingly used to gain a mechanistic understanding of the effect of TMS on the brain and to inform its administration.

We experience the world as a continuous sequence of events, but we remember the events as segmented episodes (e.g., my sister’s wedding). During encoding, we associate a sequence of relevant events and segment deviant events. At retrieval, episodic memory utilizes the encoded associations to replay the flow of events. The encoded associations lead to remembering the sequence of events that occurred within an episode better than the flow of events across segments.

During postnatal brain development, newly assembled neural circuits are refined through the strengthening of a subset of synaptic connections and the concurrent elimination of others. This process of synaptic refinement is first coordinated by intrinsically generated neural activity early in life and then driven by sensory experience during a later phase of postnatal development.

It has become increasingly clear that both spontaneous and trained behaviors engage activity throughout the cortex. However, at least in the case of perceptual decisions, task complexity critically modulates the underlying large- and mesoscale cortical dynamics. When decisions are simple sensorimotor mappings, cortical activity is correlated, and behavioral effects of inactivation are essentially restricted to the relevant sensory areas. Conversely, when decisions are complex and demanding, e.g.

Cortical GABAergic interneurons are critical components of neural circuitry, and their dysfunction has been linked to neurodevelopmental diseases. Although the diversity of interneurons is not disputed, both the extent of their heterogeneity and the gene regulatory mechanisms that drive it remain unclear. Recent advances in single cell RNA-sequencing technology have shed new light on this issue, enabling the prediction of novel interneuron subtypes based on gene expression. Cross-species meta-analysis would provide key insight into conserved mechanisms of interneuron diversity.

Playing a game of chess, driving a car, or even reading this sentence all require that the brain retain and integrate information over short periods of time. This retaining and integration of information is accomplished by working memory. The same underlying mechanisms may also allow us to hold and compare our thoughts and enable us to create a coherent awareness about our self and the world. Further, understanding how information is retained during working memory is a critical step in understanding the pathological basis of impaired working memory in advanced age.