Timothy Charles Cope, Ph.D.

Professor

Schools of Biological Sciences and Biomedical Engineering Georgia Institute of Technology
Office Address:555 14th Street NW, Atlanta, GA 30332-0356
Office:(404) 385-4293
Professor Email: timothy.cope@gatech.edu

Overview

Our research interests center on control of movement by sensorimotor integration in the mammalian spinal cord. Using predominantly electrophysiological methods applied in vivo, we study neural signaling by spinal motoneurons, somatosensory neurons, and their central synapses. Our primary analyses include electrical properties, synaptic function, and firing behavior of single neurons. We are actively examining how these neurons and synapses respond soon and long after peripheral nerve injury and regeneration. Our recent findings demonstrate that successful regeneration of damaged sensory axons does not prevent complex reorganization of their synaptic connections made within the spinal cord. In separate studies, we are examining novel mechanisms of sensory encoding and its impairment, which we recently discovered in rodents treated with anti-cancer drugs. Both nerve regeneration and chemotherapy projects are driven by the long-term goal of accurately identifying the neural mechanisms behind movement disorders. We also continue to explore fundamental operations of the normal adult nervous system. Our most recent studies focus on synaptic modulation of motoneuron firing and on interspecies comparisons of spinal circuits.

Education

B.S.,    Kinesiology, University of California, 1975
M.S.,   Kinesiology, University of California, 1977
Ph.D.,  Physiology, Duke University, 1980
Postdoctoral Fellow, Dept. Physiology and Biophysics, University of Washington 1980-1982
Postdoctoral Fellow, Brain Research Institute, University of California, Los Angeles 1982-1983

Bibliography (early publication under name T.C. Collatos)

  1. Betts, B., Smith, J.L., Edgerton, V.R., and Collatos, T.C. (1976) Telemetered EMG of fast and slow muscles in cats. Brain Res. 117:529-533.
  2. Collatos, T.C., Edgerton, V.R., Smith, J.L., and Botterman, B.R. (1977) Con­tractile proper­ties and fiber type composition of flexors and extensors of the elbow joint in cat: implication for motor control. Neuro­physiol. 40:1292-1300.
  3. Smith, J.L., Edgerton, V.R., Betts, B., and Collatos, T.C. (1977) EMG of slow and fast extensors of cat during posture, locomotion and jumping. Neurophysiol. 40:503-513.
  4. Nelson, S.G., Collatos, T.C., Niechaj, A., and Mendell, L.M. (1979) Immediate increase in Ia-motoneuron synaptic transmission caudal to spinal cord transection. Neurophysiol. 42:655-664.
  5. Collatos, T.C., Niechaj, A., Nelson, S.G., and Men­dell, L.M. (1979) Fluctua­tions in time of onset of Ia-motoneuron EPSPs in the cat. Brain Res. 160:514-518.
  6. Cope, T.C., Nelson, S.G. and Mendell, L.M. (1980) Factors outside the neuraxis mediate the “acute” increase in EPSP amplitude caudal to spinal cord transection. Neurophysiol. 44:174-183.
  7. Cope, T.C., Nelson, S.G. and Mendell, L.M. (1980) Selectivity in synaptic changes to acute spinal cord transection. Neuro­sci. Letters 20:289-294.
  8. Cope, T.C. and L.M. Mendell, L.M. (1982) Parallel fluctuation of EPSP amplitude and rise time with latency at single Ia fiber-motoneuron connections in the cat. Neurophysiol. 47:455-468.
  9. Cope, T.C. and L.M. Mendell, L.M. (1982) Distributions of EPSP latency at different group Ia fiber- alpha motoneuron connections. Neurophysiol. 47:469-478.
  10. Lucas, S.M., Cope, T.C. and Binder, M.D. (1984) Analysis of individual Ia afferent EPSPs in an homonymous motoneuron pool with respect to muscle topography. Neurophysiol. 51:61-74.
  11. Cope,T.C., Bodine, S.C., Fournier, M., and Edgerton, V.R. (1986) Soleus motor units in chronic spinal transected cats:  physiological and morphologi­cal alterations.  Neuroph­ysiol. 55:1202-1220.
  12. Botterman, B.R. and Cope, T.C. (1986) Discharge properties of motoneurons supplying distal forelimb muscles in the cat. Brain Res. 379:192-195.
  13. Cope, T.C., Fetz, E.E. and M. Matsumura, M. (1987) Synaptic strength of single Iafibre connec­tions with motoneurones in the cat spinal cord. Physiol. (Lond.) 390:161-188.
  14. Matsumura, M., Cope, T.C. and Fetz, E.E. (1988) Sustained excitatory synap­tic input to motor cortical neurons in awake animals revealed by intra­cel­lular record­ing of membrane potential. Brain Res. 70: 463-469.
  15. Botterman, B.R. and Cope, T.C. (1988) Motor-unit activation patterns during fatiguing contrac­tions of constant tension. Neurophysiol., 60:1198-1214.
  16. Botterman, B.R. and Cope, T.C. (1988) Maximum tension predicts relative endur­ance of fast-twitch motor units in the cat. Neurophysiol., 60:1215-1226.
  17. Cope, T.C., Hickman, K.R. and Botterman, B.R. (1988) Acute affects of spinal transection on EPSPs produced by single homonymous Ia fibers in soleus motoneurons in the cat. Neuroph­ysiol., 60: 1678-1694.
  18. Cope, T.C., Webb, C.B. and Botterman, B.R. (1991) Control of motor-unit tension by rate modulation during sustained contractions in reinnervated cat muscle. Neurophysiol., 65:648-656.
  19. Cope, T.C. and Clark, B.D. (1991) Motor unit recruitment in the decerebrate cat: several unit properties are equally good predictors of order. Neurophysiol., 66:1127-1138.
  20. Cope, T.C., Webb, C.B., Yee, A.K., and Botterman, B.R. (1991) Nonuniform fatigue characteristics of slow-twitch motor units activated at a fixed percentage of their maximum tetanic tension. Neurophy­siol., 65:1483-1492.
  21. Webb, C.B. and Cope, T.C. (1992) Modulation of Ia EPSP amplitude: The effects of chronic synaptic inactivity. Neurosci., 12:338-344.
  22. Webb, C.B. and Cope, T.C. (1992) The influence of synaptic identity on single Ia afferent connectivity and EPSP amplitude in the adult cat: homonymous versus heteronymous connections. Neurophy­siol., 68:1046-1052.
  23. Nemeth, P.A., Cope, T.C., Kushner, S., and Nemeth, P.M. (1993) Spatial arrangement and metabolic capacity of fiber types in self-reinnervated cat muscle. J. Physiol. (Cell Physiol. 33) 264:C411-C418.
  24. Clark, B.D., Dacko, S.M, and Cope, T.C. (1993) Cutaneous stimulation fails to alter motor unit recruitment in the decerebrate cat. Neurophysiol. 70:1433-1439
  25. Cope, T.C. and Clark, B.D. (1993) Motor unit recruitment in self-reinnervated muscles. Neurophysiol. 70:1787-1796. Published and accepted research articles in refereed journals (cont):
  26. Cope, T.C., Bonasera, S.J., and Nichols, T.R. (1994) Reinnervated muscles fail to produce stretch reflexes. Neurophysiol. 71:817-820.
  27. Dacko, S.M, Sokoloff, A.J., and Cope, T.C. (1996) Recruitment of triceps surae motor units in the decerebrate cat. I. Independence of type-S motor units in soleus and medial gastrocnemius muscles. Neurophysiol. 75:1997-2004.
  28. Sokoloff, A.J. and Cope, T.C. (1996) Recruitment of triceps surae motor units in the decerebr­ate cat. II. Heterogeneity among soleus motor units. Neurophysiol. 75:2005-2016.
  29. Seburn, K.L. and Cope, T.C. (1997) Low-frequency depression of the monosynaptic reflex is not altered by tetrodotoxin-induced nerve conduction blockade. Neurophysiol. 78:19-23.
  30. Sokoloff, A.J., Cope, T.C, Nichols, T.R., and English, A.W. (1997) Directions of torques produced about the ankle joint by cat medial gastrocnemius motor units. Motor Control 4:340-353.
  31. Alvarez, F.J., Dewey, D.E., Carr, P.A., Cope, T.C, and Fyffe, R.E.W. (1997) Down-regulation of metabotropic glutamate receptor 1a in motoneurons after axotomy. Neuroreport 8: 1711-1716.
  32. Pinter, M.J., Waldeck, R.F., Cope, T.C, and Cork, L.C. (1997) Effects of 4-aminopyridine on muscle and motor unit force in canine motor neuron disease. Neurosci. 17:4500-4507.
  33. Cope, T.C, Sokoloff, A.J., Dacko, S.M., Huot, R., and Feingold, E. (1997) Stability of motor unit force in the decerebrate cat. Neurophysiol.  78:3077-3082.
  34. Seburn, K.L., and Cope, T.C. (1998) Short-Term afferent axotomy increases both strength and depression at Ia-motoneuron synapses in rat Neurosci. 18:1142-1147.
  35. Carr, P.A., Haftel, V.K., Alvarez, F.J., Cope, T.C, and Fyffe, R.E.W. (1998) Effect of sciatic nerve transection or TTX application on enzyme activity in rat spinal cord. Neuroreport 9:357-361
  36. Clark, B.D. and Cope, T.C. (1998) Frequency-dependent synaptic depression modifies postsynaptic firing probability. Physiol. Lond. 512:189-196.
  37. Cope, T.C. and Sokoloff, A.J. (1999) Orderly recruitment among motoneurons supplying different muscles. Physiol. Paris 93:81-85.
  38. Siegel, S.G., Nichols, T.R., and Cope, T.C. (1999) Reflex activation patterns in relation to mulidirectional ankle torque in decerebrate cats. Motor Control. 3:135-150.
  39. Sokoloff, A.J., Siegel, S.G., and Cope, T.C. (1999) Recruitment order among motoneurons from different motor nuclei.  Neurophysiol. 81:2485-2492.
  40. Seburn, K.L., Catlin, P.A., Dixon, J.F., Lee, M.H., Matteson, M.S., and Cope, T.C. Decline in spontaneous activity of group A sensory afferents after sciatic nerve axotomy in rat.  Lett.274:41-44, 1999.
  41. Cope, T.C. and Sokoloff, A.J. (1999) Orderly Recruitment Tested Across Muscle Boundaries. Brain Res. 123:177-190.
  42. Buck, C.R., Seburn, K.L., and Cope, T.C. (2000) Neurotrophin expression by spinal motoneurons in adult and developing rats. Comp. Neurol. 416:309-318.
  43. Balice-Gordon, R.J., Daniel, D.B.J., J. Goldman, L.C. Cork, Shirley, A., Cope, T.C., and Pinter, M.J. (2000) Functional motor unit failure precedes neuromuscular degerneration in canine motor neuron disease. Neurol47:596-605.
  44. Alvarez, F.J., Fyffe, R.E.W., Dewey, D.E., Haftel, V.K., and Cope, T.C. (2000) Factors regulating AMPA-type glutamate receptor subunit changes induced by sciatic nerve injury in rats.  Comp. Neurol.  426:229-242.
  45. Abelew, T.A., Cope, T.C., and Nichols, T.R. (2000) Local loss of proprioception results in disruption of interjoint coordination during locomotion in the cat. Neurophysiol. 84:2709-2714.
  46. Prather, J.F., Powers, R.K., and Cope, T.C. (2001) Amplification of synaptic effects on motoneuron firing rate. Neurophysiol. 85:43-53.
  47. Haftel, V.K., Prather, J.F., Heckman, C.J., and Cope, T.C. (2001) Recruitment of cat motoneurons in the absence of homonymous afferent feedback. Neurophysiol. 86:616-628.
  48. Prather, J.F., Clark, B.D., Cope, T.C. (2002) Firing rate modulation is indistinguishable among motoneurons activated by cutaneous and muscle receptor afferents in the decerebrate cat.  Neurophysiol. 88:1867-1879.
  49. Rich, M.M., Waldeck, R.F., Cork, L.C., Balice-Gordon, R., Fyffe, R.E.W., Wang, X., Cope, T.C. and Pinter, M.J. (2002) Reduced endplate currents underlie motor unit dysfunction in canine motor neuron disease.  Neurophsyiol. 88:3293-3304.
  50. Rich, M.M., Wang, X., Cope, T.C. and Pinter, M.J. (2002) Reduced neuromuscular quantal content  with normal synaptic release time course and depression in canine motor neuron disease.  Neurophysiol.            88:3305-3314.
  51. Huyghues-Despointes CM, Cope TC, Nichols TR. (2003)  Intrinsic properties and reflex compensation in reinnervated triceps surae muscles of the cat: Effect of activation level. Neurophysiol. 90:1547-55.
  52. Huyghues-Despointes CM, Cope TC, Nichols TR. (2003)  Intrinsic properties and reflex compensation in reinnervated triceps surae muscles of the cat: Effect of movement history.  Neurophysiol. 90(3):1537-46.
  53. Haftel VK, Bichler EK, Nichols TR, Pinter MJ, Cope TC. (2004)  Movement reduces the dynamic response of muscle spindle afferents and motoneuron synaptic potentials in rat. Neurophysiol. 91(5):2164-71
  54. Carrasco DI, Rich MM, Wang Q, Cope TC, Pinter MJ. (2004) Activity-driven synaptic and axonal degeneration in canine motor neuron disease. J Neurophysiol. 92(2):1175-81.
  55. Nichols, TR and Cope, TC (2004) Cross-bridge mechanisms underlying history-dependent Properties of muscle spindles and stretch reflexes. J. Physiol. Pharmacol. 82:569-575.
  56. Wang, X, Engisch, KI, Pinter, MJ, Cope, TC, Rich MM. (2004) Decreased synaptic activity shifts the calcium dependence of release at the mammalian neuromuscular junction in vivo. J Neurosci. 24:10687-92.
  57. Riley CP, Cope TC, Buck CR. (2004) CNS neurotrophins are biologically active and expressed by multiple cell types. J MolHistol. 2004 Nov;35(8-9):771-83.
  58. Wang X, Li Y, Engisch KL, Nakanishi ST, Dodson SE, Miller GW, Cope TC, Pinter MJ, Rich MM. (2005) Activity-dependent presynaptic regulation of quantal size at the mammalian neuromuscular junction in vivo. J Neurosci. 2005 Jan 12;25(2):343-51.
  59. Nakanishi ST, Cope TC, Rich MM, Carrasco DI, Pinter MJ. (2005) Regulation of motoneuron excitability via motor endplate acetylcholine receptor activation. J Neurosci. 25:222632.
  60. Haftel VK, Bichler EK, Wang QB, Prather JF, Pinter MJ, Cope TC. (2005) Central suppression of regenerated proprioceptive afferents. J Neurosci. 25:4733-42.
  61. Bichler EK, Carrasco DI, Rich MM, Cope TC, Pinter MJ (2007) Rat motoneuron properties recover following reinnervation in the absence of muscle activity and evoked acetylcholine release. J Physiol 585:47-56.
  62. Bichler EK, Nakanishi ST, Wang QB, Pinter MJ, Rich MM, Cope TC (2007) Enhanced transmission at a spinal synapse triggered in vivo by an injury signal independent of altered synaptic activity. J Neurosci 27:12851-12859.
  63. Powers RK, Nardelli P, Cope TC. (2008) Estimation of the contribution of intrinsic currents to motoneuron firing based on paired motoneuron discharge records in the decerebrate cat. J Neurophysiol.100 (1):292-303.
  64. Novak KR, Nardelli P, Cope TC, Filatov G, Glass JD, Khan J, Rich MM. (2009) Inactivation of sodium channels underlies reversible neuropathy during critical illness in rats. J Clin Invest. 119(5):1150-8.
  65. Alvarez FJ, Bullinger KL, Titus HE, Nardelli P, Cope TC. (2010) Permanent reorganization of Ia afferent synapses on motoneurons after peripheral nerve injuries. Ann N Y Acad Sci. 1198:231-41.
  66. Alvarez FJ, Titus HE, Bullinger KL, Kraszpulski M, Nardelli P, Cope TC (2011) Permanent Central Synaptic Disconnection of Proprioceptorsafter Nerve Injury and Regeneration: I. Loss of VGLUT1/IA synapses on motoneurons. J Neurophysiol. 2011 Nov;106(5):2450-70.
  67. Bullinger KL, Nardelli P, Alvarez FJ, Cope TC (2011) Permanent Central Synaptic Disconnection of Proprioceptors after Nerve Injury andRegeneration: II. Loss of functional connectivity with motoneurons. J Neurophysiol. 2011 Nov;106(5):2471-85
  68. Honeycutt CF, Nardelli P, Cope TC, Nichols TR (2012) Muscle Spindle responses to horizontal support surface perturbation in the anesthetized cat: Insights into the role of autogenic feedback in whole body postural control. Neurophysiol. 108(5): 1253-61.
  69. Powers RK, Nardelli P, Cope TC (2012). Frequency-dependent amplification of stretch-evoked excitatory input in spinal motorneurons. Neurophysiol. 108(3): 753-59.
  70. Deardorff AS, Romer SH, Deng Z, Bullinger KL, Nardelli P, Cope TC, Fyffe REW (2013) Expression of postsynaptic Ca2+-activated K+ (SK) channels at C-bouton synapses in mammalian lumbar α-motoneurons. Journal of Physiology. 521(4), 875-897.
  71. Nardelli P, Khan J, Powers RK, Cope TC, Rich MM (2013) Reduced motoneuron excitability in a rat model of sepsis, Journal of Neurophysiology. Apr:109(7):1775-81
  72. Rotterman TM, Nardelli P, Cope TC, Alvarez FJ (2014) Normal distribution of VGLUT1 synapses on motoneuron dendrites and their reorganization after nerve injury. Journal of Neuroscience. 5;34(10):3475-92
  73. Obeidat AZ, Nardelli P, Powers RK, Cope TC. (2014) Modulation of Motoneuron Firing by Recurrent Inhibition in the Adult Rat in vivo. J Neurophysiol. 112(9):2302-15.
  74. Vincent JA, Nardelli P, Gabriel HM, Deardorff AS, Cope TC. (2015) Complex impairment of IA muscle proprioceptors following traumatic or neurotoxic injury. Anatomy. 2015 Aug; 227-30. 12312 PMID: 26047324
  75. Smilde HA, Vincent JA, Baan GC, Nardelli P, Lodder JC, Mansvelder HD, Cope TC, Maas H. (2016) Changes in muscle spindle firing in response to length changes of neighboring muscles. J Neurophysiol. 2016 Jun 1;115(6):3146-55.
  76. Nardelli P, Vincent JA, Powers R, Cope TC, Rich MM. (2016) Reduced motor neuron excitability is an important contributor to weakness in a rat model of sepsis. Exp Neurol. 2016 Aug; 282:1-8.
  77. Vincent JA, Wieczerzak KB, Gabriel HM, Nardelli P, Rich MM, Cope TC. (2016) A Novel Path to Chronic Proprioceptive Disability with Oxaliplatin: Distortion of Sensory Encoding. Neurobiol Dis. 2016
  78. Carrasco DI, Vincent JA, Cope TC (2017) Distribution of TTX-sensitive voltage-gated sodium channels in primary sensory endings of mammalian muscle spindles. J Neurophysiol. 2017 Apr 1;117(4):1690-1701
  79. Vincent JA, Gabriel, HM, Deardorff AS, Nardelli P, Fyffe REW, Burkholer TJ, Cope TC. (2017) Muscle Proprioceptors in Adult Rat: Mechanosensory Signaling and Synapse Distribution in Spinal Cord. Neurophyiosl. 2017 Nov 1;118(5):2687-2701
  80. Nardelli P, Powers R, Cope TC, Rich MM. (2017) Increasing motor neuron excitability to treat weakness in sepsis. Ann Neurol. 2017 Dec;82(6):961-971.

Invited reviews

  1. Cope, T.C. and Pinter, M.J. (1995) The Size Principle: Still Working After All These Year. News In Physiological Sciences, 10:280-286.
  2. Nichols, T.R., Cope, T.C., and Abelew, T.A. (1999) Rapid spinal mechanisms of motor coordination. Exercise and Sports Sciences Reviews, 27:255-284.

Books

  1. Cope, Timothy C., editor (2001) Motor Neurobiology of the Spinal Cord IN: Methods and Frontiers in Neuroscience Boca Raton, CRC Press.

Book chapters

  1. Edgerton, V.R., Smith, L.A., Eldred, E., Cope, T.C., and Mendell, L.M. (1980) Muscle and motor unit properties of exercised and nonexercised chronic spinal cats. IN: Plasticity of Muscle.  Editor: D. Pette. Berlin: Karger      Press, pp. 355-371.
  2. Mendell, L.M. and Cope, T.C. (1981) Fluctuations in group Ia EPSPs: Conse­quences for mechanisms of transmitter release and measured parameters of averaged EPSPs. IN:  Adv. Physiol. Sci.: Vol. 1, Regulatory Functions of the CNS. Motion and Organization Principles. Editors: J. ­Szentagoth­ai, M. Palkov­its and J. Hamori. Budapest: Pergamon Press-AkademiacKiado, pp. 55-60.
  3. Mendell, L.M., Nelson, S.G. and Cope, T.C. (1981) Functional changes caudal to spinal cord transection. IN: Lesion Induced Neuronal Plasticity in Sensorimotor Systems.  Editors: H. Flohr and W. Precht.  Heidelberg: Springer-Verlag, pp. 142-150.
  4. Mendell, L.M., Cope, T.C. and Nelson, S.G. (1982) Plasticity of the group Ia fiber pathway to motoneurons.  IN:  Proceedings of the First Institute of Neurological Sciences Symposium in Neurobiology at Univers­ity of Pennsylvania; Changing Con­cepts of the Nervous System.  Editors: P. Strick and M. Goldberger. Academic Press, pp. 69-78.
  5. Cope, T.C. and B.D. Clark. (1995) Are There Important Exceptions to the Size Principle of Alpha-Motoneuron Recruitment? IN: Alpha and Gamma Motor Systems.  Editors: A. Taylor, M.H. Gladen, and R. Durbaba. New York: Plenum Press, pp. 71-78.
  6. Cope, T.C., Sokoloff, A.J., and B.D. Clark. (1996) Size principle of motor unit recruitment: extent of its applicability. IN: Motor Control VII.  G. Stuart (editor), Motor Control Press, pp. 99-104.
  7. Cope, T.C., Seburn, K.L., and Buck, C.B. (2001) How does injury strengthen Ia-motoneuron synapses? IN: Motor Neurobiology of the Spinal Cord.  C. Cope (editor). Chapter 12, pp. 271-304.
  8. Nichols, T.R. and Cope, T.C. (2001) The Organization of Distributed Proprioceptive Feedback in the Chronic Spinal Cat.  Motor Neurobiology of the Spinal Cord.  C. Cope (editor). Chapter 13, pp. 305-326.
  9. Pinter, M.J., Cope, T.C., Cork, L.C., Green, S.L., and Rich, M.M. (2001) Canine Motor Neuron Disease: A View from the Motor Unit. IN: Motor Neurobiology of the Spinal Cord.  (T.C. Cope editor). Chapter 10, pp. 231-250.