People

Daniel Johnston, Ph.D.

My lab has been interested for many years in how single neurons process and store information. In particular, we are interested in the expression, function, and plasticity of dendritic voltage-gated ion channels. Although most of our previous work has been in hippocampus and surrounding structures (e.g., subiculum and entorhinal cortex), we began studying neurons in the prefrontal cortex about three years ago and found that their electrophysiological properties were quite variable. We used the findings from the Mauk lab to identify a subgroup of mPFC L5 neurons that project to the pons. These pons-projecting neurons had a number of unique properties compared to commissural projecting neurons and thus began the present close collaboration between our labs. [Johnston lab web page]

Mike Mauk, Ph.D.

Mike has used delay eyelid conditioning for many years to the study mechanisms of computation and learning in the cerebellum. His initial trace conditioning studies were focused on how the cerebellum processes signals from the forebrain. Since then his interest has increased greatly as 1) results revealed that trace eyelid conditioning engages working memory and persistent activity in mPFC and 2) discussions with Dan and the Johnston lab made increasingly clear that the strengths of each lab could combine synergistically to address fundamental mechanistic questions about persistent activity, working memory and behavior.

Randy Chitwood, Ph.D.

Randy uses a combination of electrophysiology with functional and structural fluorescence imaging to determine how neurons integrate information.  Using a high-speed 2-photon scanning laser microscope, we have recorded from the dendrites of labeled neurons of the mPFC. Because the majority of synaptic inputs are targeted to dendritic sites distal to the soma, direct dendritic recordings will allow us to detect learning related changes related to synaptic integration.

Nikolai Dembrow, Ph.D.

Nik joined the Johnston laboratory in June of 2007. He has been studying the effects of neuromodulators on the electrophysiological properties of L5 neurons in vitro. By performing infusions of retrograde tracer into different long-range projection targets of mPFC he has identified that L5 PFC neurons respond to neuromodulation differently depending whether they project to the pons or the contralateral cortex. This work has recently been accepted in the Journal of Neuroscience.

Brian Kalmbach, Ph.D.

Brian Kalmbach completed his Ph.D. in 2008 in the laboratory of Mike Mauk. There he identified a mPFC-to-cerebellum pathway necessary for trace eyelid conditioning.  Brian has since joined the Johnston laboratory as a post-doctoral fellow and is studying cellular changes that contribute to working memory-related neural activity in mPFC.

Jenni Siegel, Ph.D.

Jenni Siegel initially learned single-unit recording techniques during her PhD work studying the spatial activity correlates of neurons in the homing pigeon hippocampus.  She went on to sharpen her technique in the lab of James Knierim, where she recorded from hippocampal CA1 and CA3 place cells during active navigation in rats.  Now, as a post-doctoral fellow in the Mauk lab, she has confirmed the existence of persistent activity in the rabbit mPFC during trace eyelid conditioning, and is currently using pharmacological manipulations to study its development and expression, as well as antidromic stimulation to identify whether such neurons are upstream from the pons in vivo.  Jenni is particularly excited for the opportunity to  apply her expertise to the rat mPFC in collaboration with the Johnston lab in order to more precisely determine the neural mechanisms that underlie this kind of learning and memory.

Frank Riusech, M.S.

Frank Riusech joined the Mauk laboratory in 2003. He has been involved in various behavioral studies investigating learning in the cerebellum and prefrontal cortex.  He is currently working on the 3-D anatomical reconstructions of rat and rabbit prefrontal cortex, pons and cerebellum, regions that participate in trace eyelid conditioning.

Vicky Moya

Vicky Moya joined our research group in 2009. She has been actively involved in the neurobiological research community during her 3 completed years at the University of Texas at Austin. She is currently working to obtain her B.S. in neurobiology and plans to attend graduate school in the future.

Bryan Barksdale, B.S.

Bryan Barksdale is a post-bac researcher in the lab who is working on a 3D rat brain atlas. He is currently applying to MD/PhD programs.