Nervous | Laboratory of Neurobiology

Neuronal-tract-tracing methods are widely used to elucidate neural connections in the nervous system. Most commonly, the tracer substance is applied in vivo, using stereotaxic approaches to localize the area of interest. However, this ‘blind’ procedure makes the precise application of the tracer very difficult, thus frequently producing erroneous results. To overcome these difficulties, our laboratory has developed an in vitro tract-tracing method, which enables the investigator to apply tracer substances under visual control. By employing this powerful approach, we have succeeded in identifying a large number of previously unknown connections in the teleostean brain. This method can be combined with other techniques, such as immunohistochemistry. We have used such a combination to analyze the properties of neurons defined by retrograde or anterograde tracing. Examples of the latter investigations include the elucidation of the projections made by corticotropin-releasing-factor-expressing neurons in the preoptic area; and the identification of adult-born granule cell neurons in the cerebellum.

Selected Publications:

Zupanc, G.K.H., Horschke, I., Ott, R., Rascher, G.B.: Postembryonic development of the cerebellum in gymnotiform fish. Journal of Comparative Neurology 370, 443-464 (1996), doi:10.1002/(SICI)1096-9861(19960708)370:4<443::AID-CNE3>3.0.CO;2-4

Zupanc, G.K.H., Horschke, I.: Tectal input to the central posterior/prepacemaker nucleus of weakly electric fish, Apteronotus leptorhynchus: an in vitro tract-tracing study. Brain Research 739, 201-209 (1996), doi:10.1016/S0006-8993(96)00818-9

Zupanc, G.K.H.: The preglomerular nucleus of gymnotiform fish: relay station for conveying information between diencephalon and telencephalon. Brain Research 761, 179-191 (1997), doi:10.1016/S0006-8993(97)00130-3

Zupanc, G.K.H., Horschke, I.: Reciprocal connections between the preglomerular nucleus and the central posterior/prepacemaker nucleus in the diencephalon of weakly electric fish, Apteronotus leptorhynchus. Neuroscience 80, 653‑667 (1997), doi:10.1016/S0306-4522(97)00149-8

Zupanc, G.K.H., Horschke, I.: Neurons of the posterior subdivision of the nucleus preopticus periventricularis project to the preglomerular nucleus in the weakly electric fish, Apteronotus leptorhynchus. Brain Research 774, 106-115 (1997), doi:10.1016/S0006-8993(97)81693-9

Zupanc, G.K.H., Horschke, I.: A distinct population of neurons in the central posterior/prepacemaker nucleus project to the nucleus preopticus periventricularis in the weakly electric gymnotiform fish, Apteronotus leptorhynchus. Brain Research 776, 117-125 (1997), doi:10.1016/S0006-8993(97)01006-8

Zupanc, G.K.H.: An in vitro technique for tracing neuronal connections in the teleost brain. Brain Research Protocols 3, 37-51 (1998), doi:10.1016/S1385-299X(98)00019-1

Zupanc, G.K.H., Horschke, I., Lovejoy, D.A.: Corticotropin releasing factor in the brain of the gymnotiform fish, Apteronotus leptorhynchus: immunohistochemical studies combined with neuronal tract tracing. General and Comparative Endocrinology 114, 349-364 (1999), doi:10.1006/gcen.1999.7273

Corrêa, S.A.L., Zupanc, G.K.H.: Connections between the central posterior/prepacemaker nucleus and hypothalamic areas in the weakly electric fish Apteronotus leptorhynchus: evidence for an indirect, but not a direct, link. Journal of Comparative Neurology 442, 348-364 (2002), doi:10.1002/cne.10103

Corrêa, S.A.L., Zupanc, G.K.H.: Re-evaluation of the afferent connections of the pituitary in the weakly electric fish Apteronotus leptorhynchus: an in vitro tract-tracing study. Journal of Comparative Neurology 470, 39-49 (2004), doi:10.1002/cne.20009

Zupanc, G.K.H., Corrêa, S.A.L.: Reciprocal neural connections between the central posterior/prepacemaker nucleus and nucleus G in the gymnotiform fish, Apteronotus leptorhynchus. Brain, Behavior and Evolution 65, 14-25 (2005), doi:10.1159/000081107

Neural connections in the teleost nervous system

Selected Publications: