Center for Perceptual Systems

Harold Zakon


Harold Zakon



Zakon's lab studies the function and regulation of voltage-dependent ion channels using electric fish as our model organism. Electric fish generate weak electric fields as communication signals. These are produced by electric organs, which are evolution-arily and embryonically derived from muscle. The electric organ discharge (EOD) varies across species, is sexually dimorphic and individually distinct, is influenced by social factors, and may show circadian variations. Because EOD waveform must be so finely tuned in all these ways, the ionic currents of electrocytes are under exquisite regulatory control. These discharges can be easily recorded in freely behaving animals. Thus, we can essentially study dynamic biophyscial events in excitable membranes from the level of freely behaving animals to the level of the ion channels themselves. Dr. Zakon is a professor in the School of Biological Sciences, Section of Neurobiology.


McAnelly, L, Silva, A. and Zakon, HH (2003) Cyclic AMP modulates electrical signaling in a weakly electric fish. J. Comp. Physiol. A 189: 273-282.

Zakon, HH (2003) Insights from electric fish. Current Opinions in Neurobiology (invited review, in press).

Few, W.P. and Zakon, H.H. (2001) Local action of androgens and androgen receptor expression in the electric organ of a weakly electric fish. Hormones & Behavior, (in press).

Lopreato, G., Lu, Y., Southwell, A., Atkinson, N., Hillis, D., Wilcox, T. and Zakon, HH (2001) Evolution and divergence of Na+ channel genes in vertebrates. Proceedings of the National Academy of Sciences. 98: 7588-7592.

Zakon, H.H. and Smith, G.T. (2001) Hormones, behavior, and electric fish. in Hormones, Brain and Behavior, (Eds.) D.Pfaff, A.Arnold, A.Etgen, S. Fahrbach, and R. Rubin, Academic Press. (in press)

Triefenbach, F.A. and Zakon H.H. (2001) Signaling responses to sexual and reproductive status cues in the weakly electric fish, Apteronotus leptorhynchus. Animal Behaviour (in press).

Zakon, H.H. (2000) Sex Steroids and Weakly Electric Fish: A model system for Activational Mechanisms of Hormone Action. In:.Sexual Differentiation of the Brain (Ed) A. Matsumoto, CRC Press pp. 95-112.

Smith, G.T. and Zakon, H.H. (2000) Pharmacological characterization of ionic currents that regulate the rhythm of the medullary pacemaker nucleus in a weakly electric fish. J. Neurbiol 42: 270-286.

McAnelly, M.L. and Zakon, H.H. (2000) Co-regulation of voltage-dependent kinetics of Na+ and K+ currents. J. Neurosci. 20: 3408-3414.

Smith, GT, Lu, Y., and Zakon, H.H. (2000) Parvocells: A novel interneuron type in the pacemaker nucleus of a weakly electric fish. J. Comp. Neurol. 423: 427-439.

Zakon, H.H. (2000) Sensory Exotica by Howard Hughes in Nature Neuroscience

Zakon, H.H. and Unguez, G.A. (1999) Development and regeneration of the electric organ. J. Exp. Biol. 202: 1427-1434.

Zakon, H.H., McAnelly, M.L., Smith, G.T., Dunlap, K., Lopreato, G., Oestreich, J., Few, W.P. (1999) Plasticity of the electric organ discharge: implications for the regulation of ionic currents. J. Exp. Biol. 202: 1409-1416.

Zakon, H.H. and Dunlap, K.D. (1999) Sex hormones and communication signals: a tale of two species. Brain, Behavior, and Evolution 54: 61-69.

Zakon, H.H. (1998) Effects of steroid hormones on electrical activity of excitable cells. Trends in Neurosciences 21: 202-207.

Unguez, G.A, and Zakon, H.H. (1998) Phenotypic conversion of distinct muscle fiber populations to electrocytes in a weakly electric fish. J. Comp. Neurol. 399: 20-34.

Dunlap, K. and Zakon, H. (1998) Hormones and reproductive communication signals in fish. Encyclopedia of Reproduction. Editors-in-Chief, E. Knobil and J.D. Neil. Academic Press, vol. 2, pp. 64-71.

Zakon, H.H., Lu, Y. and Weisleder, P. (1998) Sensory cells determine afferent terminal morphology in cross-innervated electroreceptor organs: implications for hair cells. J. Neurosci. 18: 2581-2591.

Dunlap, K., Thomas, P., Zakon, H.H. (1998) Diversity of sexual dimorphism in electrocommunication signals and its androgen regulation in a genus of electric fish, Apteronotus. J. Comp. Physiol A 183: 77-86.

Zakon, H.H., Gustavson, S. and Prins, G. (1998) Distribution of androgen receptors in the brain, electric organ and electroreceptors of the weakly electric fish, Sternopygus. J. Comp. Neurol.

Dunlap, K.D. and Zakon, H.H. (1998) Behavioral actions of androgens and androgen receptor expression in the electrocommunication system of an electric fish, Eigenmannia virescens. Hormones and Behavior 34: 30-38.

Unguez, G.A. and Zakon, H.H. (1998) Re-expression of myogenic proteins in mature electric organ following removal of neural input. J. Neuroscience 18: 9924-9935.

Dunlap, K., McAnelly. L.M., and Zakon, H.H. (1997) Estrogen modifies an electrocommunication signal by altering the electrocyte sodium current in an electric fish, Sternopygus. J. of Neurosci. 17: 2869-2875.

Patterson, J.M. and Zakon, H.H. (1997) Transdifferentiation of muscle to electric organ: regulation of muscle-specific proteins is independent of patterned nerve activity. Dev. Biol. 186: 115-126.

Weisleder, P. and Zakon, H.H. (1996) Tuberous electroreceptor organs form in denervated regenerating skin of a weakly electric fish. J. Comp. Neurol. 376: 563-574.

Schaefer, J.E. and Zakon, H.H. (1996) Opposing actions of androgen and estrogen on in vitro firing frequency of neuronal oscillators in the electromotor system. J. Neuroscience 16: 2860-2868.

Patterson, J.M. and Zakon, H.H. (1996) Differential expression of proteins in muscle and electric organ, a muscle derivative. J. Comp. Neurol. 370: 367-376.

Zakon, H.H. (1996) Hormonal modulation of communication signals in electric fish. Devel. Neurosci. 18: 115-123.

McAnelly, L. and Zakon, H.H. (1996) Protein kinase A activation increases sodium current magnitude in the electric organ of Sternopygus. J. Neuroscience 16: 4383-4388.

Zakon, H.H. (1995) Electric organs: structure, physiology, hormone-sensitivity, and biochemistry. Biochemistry and Molecular Biology of Fishes, Vol. IV (Ed.) T. Mommsen and P. Hochachka, Elsevier chapter 11: pp. 259-277.

Ferrari, M.B., McAnelly, L.M. and Zakon, H.H. (1995) Individual variation in and androgen-modulation of the sodium current in electric organ. J. Neuroscience 15: 4023-4032.

Zakon, H.H. (1994) Techniques for recording from electric organs. in Biochemistry and Molecular Biology of Fishes, Vol. III (Ed.) T. Mommsen and P. Hochachka, Elsevier chapter 9: pp. 93-106.

Weisleder, P., Lu, Y., and Zakon, H.H. (1994) Effects of denervation upon receptor cell survival and basal cell proliferation in tuberous electroreceptor organs of a weakly electric fish. J. Comp. Neurol. 347: 545-552.

Patterson, J. and Zakon, H.H. (1993) Bromodeoxyuridine labeling reveals satellite-like cells in the electric organ. J. Neurobiology 24: 660-674.

Ferrari, M.B. and Zakon, H.H. (1993) Conductances contributing to the action potential of Sternopygus electrocytes. J. Comp. Physiol. A 173: 281-292.

Zakon, H.H. (1993) Weakly electric fish as model systems for studying long-term steroid action on neural circuits. Brain, Behav. and Evol. 42: 242-251.

Fleishman, L., Lemon, W., and H.H. Zakon (1992) Communication in the weakly electric fish Sternopygus macrurus. II. Behavioral test of conspecific EOD detection ability. J. Comp. Physiol. A, 170: 349-356.

Mills, A.C., H.H. Zakon, Marchaterre, M.A. and A.H. Bass (1992) Electric organ morphology of Sternopygus macrurus, a wave-type, weakly electric fish with a sexually dimorphic EOD. J. Neurobiol. 23: 920-932.

Zakon, H.H. (1992) Neural Nets in Electric Fish by Walter Heiligenberg in Trends in Neurosciences.

Mills, A. C. and H.H. Zakon (1991) Chronic androgen treatment increases action potential duration in the electric organ of Sternopygus. J. Neuroscience 11(8): 2349-2361.

Zakon, H.H. (1991) Regeneration of electroreceptors in weakly electric fish. in: Regeneration of Vertebrate Sensory Receptor Cells E. Rubel, (Ed.), Wiley Chichester, (CIBA Foundation symposium 160), pp. 294-313.

Zakon, H.H., Thomas, P. and Yan, H.-Y. (1991) Electric organ discharge frequency and plasma sex steroid levels during gonadal recrudescence in a natural population of the weakly electric fish Sternopygus macrurus. J. Comp. Physiol. A 169: 493-499.

Zakon, H.H., A.C. Mills and M. Ferrari (1991) Androgen-modulation of the electrical activity of the electrosensory system of a weakly electric fish. Seminars in the Neurosciences. 3: 449-457.

Zakon, H.H. (1991) Electrocommunication in Teleost Fish: behavior and experiments by Bernd Kramer in Trends in Neurosciences.

Sanchez, D.Y. and H.H. Zakon (1990) The effects of postembryonic cell addition on the response properties of electroreceptive afferents. J. Neuroscience 10: 361-369.

Zakon, H.H., H.-Y. Yan and P. Thomas (1990) Human chorionic gonadotropin-induced shifts in the electrosensory system of the weakly electric fish, Sternopygus. J. Neurobiology 21: 826-833.

Fritzsch, B., H.H. Zakon and D. Y. Sanchez (1990) The time course of structural changes in regenerating electroreceptors of a weakly electric fish. J. Comp. Neurol. 300: 386-404.

Lannoo, M.J., L.Maler and H. H. Zakon (1989) Nerve branch-independent somatotopy in the primary afferent projection of weakly electric teleosts (Gymnotifornes). Neuroscience Letters 97: 11-17.

Fritzsch, B. and H.H. Zakon (1989) A simple, reliable and inexpensive silver stain for nerve fibers in bleached skin. Zeitschrift für Naturforschung 43: 606-.

Ferrari, M. and H.H. Zakon (1989) The tuning of electroreceptors is independent of the activity of the pacemaker nucleus. J. Neuroscience 9: 1354-1361.

Bell, C.C., H. H. Zakon and T. Finger (1989) Studies on mormyromast electroreceptor organs and their afferents in mormyrid fish: I. Morphology. J. Comp. Neurol. 186: 391-407.

Zakon, H.H. (1988) Electroreceptors: diversity in structure and function. in: Sensory Systems of Aquatic Animals. A.N. Popper, R.R. Fay, J. Atema, W.N. Tavolga (Eds). Springer-Verlag, New York. pp. 813-850.

Zakon, H.H. and W. Wilczynski (1988) The Physiology of the Anuran VIIIth Nerve. in: The Amphibian Auditory System, B. Fritzsch, W. Wolkowiak, M.J. Ryan, W. Wilczynski, T. Hetherington (Eds.) pp. 125-155.

Zakon, H.H. (1988) Regeneration of the Amphibian Auditory System. in: The Amphibian Auditory System, B. Fritzsch, W. Walkowiak, M.J. Ryan, W. Wilczynski, T. Hetherington (Eds.) pp. 393-411.

Zakon, H.H. (1987) Regeneration and Recovery of Function in the Amphibian Auditory System. in: Biology of Change in Otolaryngology: Developmental Biology, Plasticity and Compensation, and Injury and Repair Mechanisms. Ruben, R. and Van de Water, T. (Eds.) Elsevier Press, Amsterdam. pp 305-317.

Mills, A. and H.H. Zakon (1987) Coordination of EOD frequency and pulse duration in a weakly electric wave fish: the influence of androgens. J. Comp. Physiol. A 161: 417-430.

Zakon, H.H. (1987) Variation in the mode of receptor cell addition in the electrosensory system of gymnotiform fishes. J. Comp. Neurol. 262: 195-214.

Zakon, H.H. (1987) Hormone-mediated Plasticity In the Electrosensory System of Weakly Electric Fish. Trends in Neuroscience 10: 416-421.

Keller, C., H.H. Zakon, and D.Y. Sanchez (1986) Evidence for a direct effect of androgens upon electroreceptor tuning. J. Comp. Physiol. A 158: 301-310.

Zakon, H.H. (1986) Emergence of tuning in newly-generated tuberous electroreceptors. J. Neurosci. 6: 3297-3308.

Zakon, H.H. (1986) The Electroreceptive Periphery. in: Electroreception, T.H. Bullock and W. Heiligenberg, (Eds.), John Wiley Inc., N.Y., pp 103-156.

Wilczynski, W., H.H. Zakon, and G.D. Pollak (Editors) (1986) Common Principles in the Neuroethology of Acoustic and Electric Communication. Symposium Proceedings published in Brain, Behavior and Evolution. 28, 156 pp.

Zakon, H.H. (1984) Fish Neurobiology (Ed.) R.G. Northcutt and R. Davis for Copeia. no2. 559-560.


Semester       Course        Unique No.            Title

2014 Fall      NEU 365R         56790               Vertebrate Neurobioloyg
2014 Fall      NEU 367V         56900               Evolutionary Neurobiology

2013 Fall      Bio 365R           50905               Vertebrate Neurobiology
2013 Fall      Bio 365R           50910               Vertebrate Neurobiology
2013 Fall      Bio 365R           50915               Vertebrate Neurobiology 



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