Ongoing Projects

 
Project | 02
Fragile X, the most common inherited form of autism, is a condition associated with deficits in perceptual learning. We sought to characterize experience dependent oscillations in a mouse model of Fragile X (Fmr1 KO) using a multi-faceted experimental approach. We made use of the variety of tools at our disposal such as extracellular electrophysiology in V1, visually evoked behavior analysis, cross-layer functional connectivity in V1, and channelrhodopsin-2 assisted circuit mapping (CRACM) of selected connections.
 
Extracellular recordings revealed impaired oscillatory activity in Fragile X mice characterized by lower amplitudes, shorter oscillation durations, and oscillation frequency shift. Functional connectivity and CRACM analysis identified altered connectivity in Fragile X mice, providing insight into the circuit level changes.
 
By studying experience dependent oscillations in FX mice, we have gained new insights into perceptual impairments in autism and the components of the circuits that may generate the oscillations themselves. 

V1 impairments in Fmr1 KO Mice

Project | 01
Experience shapes neural activity in the brain at many scales, from the single synapses to large populations of neurons. To examine changes at the population level, we use multi-channel electrophysiology to record from primary visual cortex (V1) in awake mice. We found that repetitively presenting visual stimuli over several days profoundly changes the visually evoked responses to that stimuli. That is, before visual experience visually evoked responses are primarily stimulus locked, but afterwards they become persistent low frequency oscillations. Interestingly, these oscillations are specific to the spatial frequencies of the familiar stimulus. Our results suggest that these oscillations may represent a neural correlate of visual familiarity. Many of the efforts in this project have been focused on characterizing the fundamental properties of this oscillatory phenomenon, including oscillation duration, stimulus specificity, dynamics, and sensitivity to neuromodulation.

Oscillatory encoding of visual familiarity

Project | 03
Development of treatments for brain injuries and neurological diseases is a continuing challenge complicated by rare adult neurogenesis and poor functional recovery. A recent development which shows promise is in vivo direct NeuroD1-mediated astrocyte-to-neuron conversion. However, the mechanism of this conversion is poorly understood. To gain insight into this process, we use in vivo extracellular recordings, ex vivo channelrhodopsin-2 assisted circuit mapping, and  two photon calcium imaging techniques. We seek to understand how the newly reprogrammed cells integrate into the functional neural circuit, acquire visually evoked responses, and restore function after in vivo direct reprogramming in the mouse visual cortex following focal ischemia. 

Direct Reprogramming of Astrocytes into Neurons

Project | 04
In collaboration with the Ferndandez-Juricic Lab at Purdue University, we are developing the techniques to record from retinal ganglion cells in the avian retina. Currently, there are many mysteries to be answered by examining the avian retina. What does the retina tell the brain about color? What do double cones do? This technique will enable us to develop better models of avian vision, enhance conservation efforts, and provide some basic insights into the retinal function of an entire class of animals found worldwide. Our first goal is to profile the color responses of retinal ganglion cells in two passerine species (European Starling and House Sparrow), and to examine the retinal circuitry that supports color vision in these species. 

Patching in the Avian Retina

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