Harold L. Atwood, Ph.D., D.Sc., FRSC

Dr. Harold Atwood

Dr. Harold Atwood

Harold L. Atwood, Ph.D., D.Sc., FRSC

Harold Atwood’s academic training, in biology and neurophysiology, was at the University of Toronto (B.A.) , the University of California at Berkeley (M.Sc.), the University of Glasgow, Scotland (Ph.D., D.Sc.), the University of Oregon, and the California Institute of Technology (Post-doctoral studies).

He obtained an academic position at the University of Toronto in 1965, and continued his academic career there until retirement in 2002. Initially in the Department of Zoology, he was recruited as the Chair of the Department of Physiology in 1981, and held that position for almost a decade. His significant contributions to this Department are detailed in this History of University of Toronto’s Physiology Department (view page 11).

He then formed the Medical Research Council of Canada Research Group in Nerve Cells and Synapses, directing it until 2000.

Teaching activities included initiation of neuroscience teaching in the Department of Zoology, training numerous graduate students and post-doctoral workers who dispersed to universities in Canada, the United States, France, Sweden, Austria, Australia, and England, and promoting teaching initiatives in the Department of Physiology.

In administration, he recruited many faculty members to the Department of Physiology, which has become the largest such department in Canada.

He was involved in many committees, granting agencies, and administrative positions in Toronto, in Canada, and internationally, including Editor of the Canadian Journal of Physiology and Pharmacology, and President of the Canadian Association for Neuroscience.

He has received many awards and recognitions, including a Guggenheim Fellowship, Fellow of the Royal Society of Canada, Distinguished Scientist of the Medical Research Council of Canada, Fry Medalist of the Canadian Society of Zoologists, and others.

Harold Atwood’s research addresses the physiology of muscular contraction, motor control, synaptic transmission, and synaptic modification in the nervous systems and neuromuscular systems of both arthropods (insects and crustaceans) and mammals.

By far the largest part of this work was on neuromuscular systems of crustaceans, which have been frequently studied by physiologists because their muscle cells and motor neurons attain a relatively large size and are relatively few in number (and thus readily identifiable and experimentally accessible in the intact animal or in isolated tissues). The work was extended to synapses of the genetically tractable fruit fly, Drosophila. Nerve cells investigated undergo several activity-dependent long-term changes which have adaptive value and occur in other species. The findings have general significance for performance and experience-dependent modification of nervous and neuromuscular systems.

The combination of ultrastructural and physiological analyses developed by Dr. Atwood and co-workers has provided unique insights into factors determining the strength of synaptic actions in the nervous system, and how these can be modified.

Among the significant results, discovery and analysis of long-term synaptic adaptation, the first demonstrations of ‘silent’ synapses which can be recruited by activity, and the role of differential sensitivity to calcium ions as a key factor in synaptic performance are of general interest.

Selected significant publications:

  1. Atwood, H.L., Hoyle, G. and Smyth, T. (1965) Mechanical and electrical responses of single innervated crab-muscle fibres. Journal of Physiology (London), 180, pp. 449-482.
  2. Atwood, H.L., and Hoyle, G. (1965) A further study of the paradox phenomenon of crustacean muscle. Journal of Physiology (London), 181, pp. 225-234.
  3. Atwood, H.L. and Bittner, G.D. (1971) Matching of excitatory and inhibitory inputs to crustacean muscle fibers. Journal of Neurophysiology, 34, pp. 157-170.
  4. Sherman, R.G. and Atwood, H.L. (1971) Synaptic facilitation: Long-term neuromuscular facilitation in crustacean muscles. Science, 171, pp. 1248-1250.
  5. Luff, A.R. and Atwood, H.L. (1971) Changes in the sarcoplasmic reticulum and transverse tubular system of fast and slow skeletal muscles of the mouse during post-natal development. Journal of Cell Biology, 51, pp. 369-383.
  6. Jahromi, S.S. and Atwood, H.L. (1974) Three-dimensional ultrastructure of the crayfish neuromuscular apparatus. Journal of Cell Biology, 63, pp. 599-613.
  7. Wojtowicz, J.M. and Atwood, H.L. (1984) Presynaptic membrane potential and transmitter release at the crayfish neuromuscular junction. Journal of Neurophysiology, 52, pp. 99-113.
  8. Lnenicka, G.A. and Atwood, H.L. (1985) Age-dependent long-term adaptation of crayfish phasic motor axon synapses to altered activity. Journal of Neuroscience, 5, pp. 459-467.
  9. Wojtowicz, J.M. and Atwood, H.L. (1985) Correlation of presynaptic and postsynaptic events during establishment of long-term facilitation at crayfish neuromuscular junction. Journal of Neurophysiology, 54, pp. 220-230.
  10. Atwood, H.L. and Wojtowicz, J.M. (1986) Short-term and long-term plasticity and physiological differentiation of crustacean motor synapses. International Review of Neurobiology, 28, pp. 275-362.
  11. Atwood, H.L. and Tse, F.W. (1988) Changes in binomial parameters of quantal release at crustacean motor axon terminals during presynaptic inhibition. Journal of Physiology (London), 402, pp. 177-193.
  12. Dixon, D. and Atwood, H.L. (1989) Conjoint action of phosphatidylinosital and adenylate cyclase systems in serotonin-induced facilitation at the crayfish neuromuscular junction. Journal of Neurophysiology, 62, pp. 1251-1259.
  13. Atwood, H.L., Govind, C.K. and Wu, C.-F. (1993) Differential ultrastructure of synaptic terminals on ventral longitudinal abdominal muscles in Drosophila larvae. Journal of Neurobiology, 24, pp. 1008-1024.
  14. Wojtowicz, J.M., Atwood, H.L., and Marin, L. (1994) Activity-induced changes in synaptic release sites in the crayfish neuromuscular junction. Journal of Neuroscience, 14, pp. 3688-3703.
  15. Msghina, M., Millar, A.G., Charlton, M.P., Govind, C.K., and Atwood, H.L. (1999) Calcium entry related to active zones and differences in transmitter release at phasic and tonic synapses. Journal of Neuroscience, 19, pp. 8419-8434.
  16. Renger, J.J., Atwood, H.L., Govind, C.K., and Wu, C.-F. (2000) Role of cAMP cascade in synaptic stability and plasticity: ultrastructural and physiological analyses of individual synaptic boutons in Drosophila memory mutants. Journal of Neuroscience 20, pp. 3980-3992.
  17. Macleod, G.T., Hegström-Wojtowicz, M., Charlton, M.P., and Atwood, H.L. (2002) Fast calcium signals in Drosophila motorneuron terminals. Journal of Neurophysiol. 88, pp. 2659-2663.
  18. Millar, A.G., Bradacs, H., Charlton, M.P., and Atwood, H.L. (2002) Inverse relationship between release probability and readily releasable vesicles in depressing and facilitating synapses. Journal of Neuroscience 22, pp. 9661-9667.
  19. Millar, A.G., Zucker, R.S., Ellis-Davies, G.C.R., Charlton, M.P. and Atwood, H.L. (2005) Calcium sensitivity of neurotransmitter release differs at phasic and tonic synapses. Journal of Neuroscience 25, pp. 3113-3125.
  20. Dason, J.S., Romero-Pozuelo, J., Atwood, H.L. and Ferrus, A. (2012) Multiple roles for Frequenin/NCS-1 in synaptic function and development. Molecular Neurobiology 45, pp. 388-402.