John P. Walsh

Associate Professor of Gerontology
Member USC Program in Neuroscience

John P. Walsh

Research Topics

  • Striatum
  • synaptic plasticity
  • aging
  • calcium and ROS physiology

Research Images

Striatal medium spiny neuronspines from medium spiny neuron

Research Overview

The focus of my laboratory is to understand dopamine and glutamate synaptic physiology in the striatum under normal and pathological conditions. We use the analysis of short and long-term synaptic plasticity at corticostriatal synapses to study striatal pathology and rely upon, whole cell voltage clamp, intracellular and field potential recordings in the analysis. We also use fast-scan cyclic voltammetry to study dopamine physiology in the same brain slices. A parallel study is being performed in aged animals to describe how aging impacts synaptic integration and the mechanisms for any observed changes caused by the aging process.

Another interest in the laboratory is to describe the modulation of synaptic function and key conductances in striatal neurons following the generation of reactive oxygen species (ROS) under conditions of hypoxia. Part of this NIH funded study uses the complex II inhibitor 3-nitropropionic acid (3-NP) to examine acute and long-term survival and the synaptic consequences of chemical hypoxia.

We also have been studying the impact of MPTP treatment on striatal physiology in mice and the restoration of function created by intense treadmill exercise in collaboration with Drs. Mike Jakowec and Giselle Petzinger from USC's Department of Neurology.

These research interests are connected by the underlying hypotheses that aging and disease create shifts in ROS homeostasis, which possibly follow similar pathways in the striatum.

Contact Information

Mailing Address University of Southern California
Andrus Gerontology Center
3715 McKlintock
Los Angeles, CA 90080-0191
Office Location Gerontology (GERO) 244
Office Phone (213) 740-4908
Lab Location GERO 242
Lab Phone (213) 740-4909
Fax (213) 740-0792
Office Location Gerontology (GERO) 244



  • B.S., University of California at Irvine, 1979.
  • Ph.D., University of Texas Health Science Center at Houston, 1985.
  • Post-doctoral Scholar, UCLA Medical School, 1985-1989.

Selected Publications

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  • VanLeeuwen J, Petzinger GM, Vuckovic M, Akopian G, Ramirez M, Walsh JP, Jakowec MW (2010). Altered AMPA-Receptor Expression with Treadmill Exercise in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-Lesioned Mouse Model of Basal Ganglia Injury. J Neurosci Res., 88: 650-668. PubMed Link
  • Akopian G, Crawford C, Beal MF, Cappelletti M, Jakowec MW, Petzinger G, Gheorghe SL, Chow R, Walsh JP (2008). Decreased striatal dopamine release underlies increased expression of long-term synaptic potentiation at corticostriatal synapses 24 hours after 3-nitropropionic acid induced chemical hypoxia. J Neurosci., 28: 9585-9597.

    PubMed Link
  • Petzinger GM, Walsh JP, Akopian G, Hogg E, Abernathy A, Arevalo P, Turnquist P, Vuckovic M, Fisher BE, Togasaki DM, Jakowec MW. (2007) Effects of treadmill exercise on dopaminergic transmission in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-lesioned mouse model of basal ganglia injury. J Neurosci. 27(20):5291-300. PubMed Link
  • Akopian G, Walsh JP. (2007) Reliable long-lasting depression interacts with variable short-term facilitation to determine corticostriatal paired-pulse plasticity in young rats. J Physiol. 580(Pt 1):225-240. PubMed Link
  • Akopian G, Walsh JP. (2006) Pre- and postsynaptic contributions to age-related alterations in corticostriatal synaptic plasticity. Synapse. 60(3):223-238. PubMed Link
  • Boonplueang R, Akopian G, Stevenson FF, Kuhlenkamp JF, Lu SC, Walsh JP, Andersen JK. (2005) Increased susceptibility of glutathione peroxidase-1 transgenic mice to kainic acid-related seizure activity and hippocampal neuronal cell death. Exp Neurol. 192(1):203-214. PubMed
  • Akopian G, Walsh JP. (2002) Corticostriatal paired-pulse potentiation produced by voltage-dependent activation of NMDA receptors and L-type Ca(2+) channels. J Neurophysiol. 87(1):157-165. PubMed
  • Fitzpatrick JS, Akopian G, Walsh JP. (2001) Short-term plasticity at inhibitory synapses in rat striatum and its effects on striatal output. J Neurophysiol. 85(5):2088-2099. PubMed
  • Smith R, Musleh W, Akopian G, Buckwalter G, Walsh JP. (2001) Regional differences in the expression of corticostriatal synaptic plasticity. Neuroscience. 106(1):95-101. PubMed
  • DeFazio RA, Pong K, Knusel B, Walsh JP. (2000) Neurotrophin-4/5 promotes dendritic outgrowth and calcium currents in cultured mesencephalic dopamine neurons. Neuroscience. 99(2):297-304. PubMed