Research Projects

Project Summary Cell signaling pathways in the brain are an essential part of a complex system regulating the activity and coordination of neuronal circuits. During learning and memory synaptic plasticity processes regulate the strength of synaptic connections and modify neuronal circuits. Intracellular signaling pathways play critical roles in regulating synaptic strength and are an important part of the molecular mechanisms underlying learning and memory.

Project Summary/Abstract: The emerging field of optogenetics — using light to engage biological systems — holds tremendous promise for dissection of neural circuits, cellular signaling and manipulating neurophysiological systems in awake, behaving animals.

Deciphering neural coding will require deconstructing the complex and intertwined signaling mechanisms that drive cellular excitability, synaptic plasticity, and circuit dynamics in the brain. This fundamental objective has been extremely challenging because unraveling the temporal and spatial interactions of multiple signaling pathways requires coordinated observation of multiple networks within individual cells and multiple neurons within intact circuits.

Project Summary:    Fundamental  to  furthering  our  understanding  of  the  brain  is  the  ability  to  longitudinally  track  changes  in  gene  expression  over  time  in  different  contexts  (e.g.  development  or  learning) (Aim 1) and to develop methods to target and manipulate specific neuronal cell  types regardless of species (Aim 2). &nb

Summary A central challenge in neuroscience is to develop methods to manipulate specific cell types within the mammalian brain. Recent developments in optogenetics have revolutionized our ability to control the activity of both neurons and non-neuronal cells. However, this approach suffers from one drawback, the difficulty in delivery light stimulus to target cells that are located deep within the brain or the body. The Chalasani lab has recently demonstrated a noninvasive method to control the activity of neurons.

Project Summary The main objective of the proposed research is to develop a wearable transcranial focused ultrasound (tFUS) environment that reversibly modulates (either elicits or suppresses) region-specific neural activities of the brain.

Project Abstract Completely noninvasive neuromodulation using focused ultrasound (FUS) offers the promise of precisely stimulating specific targets deep in the brain. FUS is already used to deliver precise ablations deep in the brain. A CT scan is currently used to calculate the phase aberration corrections. The focal spot is calibrated by imaging a 5°C temperature rise. Both the CT scan and tissue heating are unacceptable in normal volunteers. Beyond that, skulls with similar CT scans vary widely in their ultrasound attenuation.

Project Summary/Abstract: During the past two decades, functional Magnetic Resonance Imaging (fMRI) has become ubiquitous in studies of the human brain function. Similarly, Transcranial Magnetic Stimulation (TMS) has established its role as one of the most widely used neuromodulation techniques. Both of these methods have gained popularity due to their safe and noninvasive nature in addition to their wide availability.

This project will develop a low-noise transcranial magnetic stimulation (TMS) system. TMS is a technique for non-invasive brain stimulation using strong, brief magnetic pulses. TMS is widely used as a tool for probing brain function and is an FDA approved treatment for depression. A significant limitation of TMS, however, is that the magnetic pulse delivery is associated with a loud clicking sound as high as 140 dB resulting from electromagnetic forces. The loud noise significantly impedes both basic research and clinical applications of TMS.

Abstract This project seeks to develop a wireless, minimally invasive bi-directional deep brain stimulation technology based on remote heating of magnetic nanoparticles. Reliably modulating the activity of specific neuronal populations is essential to establishing causal links between neural firing patterns and observed behaviors. Electrical stimulation, as well as its recent non-invasive alternatives, ultrasound and electromagnetic induction, do not discriminate between cell types and have limited spatial resolution.