Daniel Johnston

Daniel Johnston, PhD
Director, Center for Learning and Memory
Director, Institute of Neuroscience

   E-mail: djohnston@mail.clm.utexas.edu

   Website: http://www.clm.utexas.edu/djlab06/

Main Office:NMS 4.104 Phone: 512-232-6564

Alternate Office: NMS 4.210 Phone: 512-475-7905


   Mailing Address:
      Center for Learning and Memory
      The University of Texas at Austin
      1 University Station Stop C7000
      Austin, TX 78712-0805


Research Summary:
   

Research in my laboratory is primarily directed towards understanding the cellular and molecular mechanisms of synaptic integration and long-term plasticity of neurons in the medial temporal lobe. We have focused our attention on the hippocampus, subiculum, and entorhinal cortex, areas of the brain that play important roles in learning and memory. These regions are also of interest because they have a low seizure threshold and are implicated in several forms of human epilepsy. Our research uses quantitative electrophysiological, optical-imaging, and computer-modeling techniques.

 

We are investigating long-term synaptic potentiation and depression, forms of plasticity thought to underlie aspects of memory. This interest has led us to investigate the basic mechanisms of synaptic integration in the dendrites of the neurons in these regions. We have used fluorescence imaging techniques and dendritic patch-clamp recordings to identify the types of voltage-gated ion channels (Na+, K+, Ca+, and h channels) expressed in dendrites of hippocampal and entorhinal cortex pyramidal neurons. We have also begun to identify changes in the properties and expression levels of some of these channels accompanying synaptic potentiation and depression. These studies have suggested that plasticity of intrinsic excitability of neurons is an important component of learning and memory. Our computer modeling studies, which reconstruct the biophysical properties of these neurons based on our experimental data, complement this work. We hope that these investigations will enhance our understanding of the neuronal mechanisms of learning and memory and provide insight into the function of the hippocampus and neighboring cortex in the normal behaving animal as well as under disease states such as epilepsy.

 


Select Publications:

2006

Chen, X. and Johnston, D, Voltage-gated ion channels in dendrites of hippocampal neurons., Pflugers Arch Volume 453, Pages 397-401

2006

Chen, X., Yuan, L.-L., Zhao, C., Birnbaum, S.G., Frick, A., Jung, W.E., Schwarz, T.L., Sweatt, J.D., and Johnston, D., Deletion of Kv4.2 gene eliminates dendritic A-type K+ current and enhances induction of long-term potentiation in hippocampal CA1 pyramidal neurons., J. Neurosci Volume 26, Pages 12143-12151

2006

Rosenkranz, J.A. and Johnston, D., Voltage-dependent dopaminergic regulation of neuronal excitability through modulation of Ih in layer V entorhinal cortex, J. Neuroscience Volume 26, Pages 3229-3244

2005

Frick, A. and Johnston, D., Plasticity of dendritic excitability, J. Neurobiol Volume 64, Pages 100-115

2005

Fan, Y, Fricker, D., Brager, D., Chen, X, Lu, H.C, Chitwood, R, and Johnston, D., Activity-dependent decrease of excitability in hippocampal neurons through increases in Ih, Nature Neuroscience Volume 8, Pages 1542-1551

2005

Koester, H.J. and Johnston, D., Target-Cell Dependent Normalization of Transmitter Release at Neocortical Synapses., Science Volume 308, Pages 863-866

2004

Frick, A., Magee, and Johnston, D, LTP is accompanied by an enhanced local excitability of pyramidal neuron dendrites., Nature Neuroscience Volume 7, Pages 126-135

2004

Bernard, C., Anderson, A.E. Poolos, N.P., and Johnston, D, Acquired dendritic channelopathy in temporal lobe epilepsy., Science Volume 305, Pages 532-535

2004

Shah, M.M., Anderson, A.E., Leung, V., and Johnston, D., Seizure-induced plasticity of {\it h}-channels in entorhinal cortical layer III neurons. , Neuron Volume 2004, Pages 495-508