A dye mixture (Neurobiotin and Alexa 488) reveals extensive dye-coupling among neurons in leeches; physiology confirms the connections.

Ruey Jane Fan, Antonia Marin-Burgin, Kathleen A. French, W. Otto Friesen

Research output: Contribution to journalArticle

Abstract

Although the neuronal circuits that generate leech movements have been studied for over 30 years, the list of interneurons (INs) in these circuits remains incomplete. Previous studies showed that some motor neurons (MNs) are electrically coupled to swim-related INs, e.g., rectifying junctions connect IN 28 to MN DI-1 (dorsal inhibitor), so we searched for additional neurons in these behavioral circuits by co-injecting Neurobiotin and Alexa Fluor 488 into segmental MNs DI-1, VI-2, DE-3 and VE-4. The high molecular weight Alexa dye is confined to the injected cell, whereas the smaller Neurobiotin molecules diffuse through gap junctions to reveal electrical coupling. We found that MNs were each dye-coupled to approximately 25 neurons, about half of which are likely to be INs. We also found that (1) dye-coupling was reliably correlated with physiologically confirmed electrical connections, (2) dye-coupling is unidirectional between MNs that are linked by rectifying connections, and (3) there are novel electrical connections between excitatory and inhibitory MNs, e.g. between excitatory MN VE-4 and inhibitory MN DI-1. The INs found in this study provide a pool of novel candidate neurons for future studies of behavioral circuits, including those underlying swimming, crawling, shortening, and bending movements.

Original languageEnglish (US)
Pages (from-to)1157-1171
Number of pages15
JournalJournal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology.
Volume191
Issue number12
StatePublished - Dec 2005
Externally publishedYes

Fingerprint

Leeches
leech
Hirudinea
Motor Neurons
motor neurons
physiology
dyes
dye
Coloring Agents
neurons
interneurons
Interneurons
Neurons
inhibitor
gap junctions
neurobiotin
Gap Junctions
shortenings
Molecular Weight
molecular weight

ASJC Scopus subject areas

  • Animal Science and Zoology
  • Physiology
  • Physiology (medical)
  • Behavioral Neuroscience
  • Neuroscience(all)

Cite this

A dye mixture (Neurobiotin and Alexa 488) reveals extensive dye-coupling among neurons in leeches; physiology confirms the connections. / Fan, Ruey Jane; Marin-Burgin, Antonia; French, Kathleen A.; Otto Friesen, W.

In: Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology., Vol. 191, No. 12, 12.2005, p. 1157-1171.

Research output: Contribution to journalArticle

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