Commissural neurons of the electrosensory lateral line lobe of Apteronotus leptorhynchus: morphological and physiological characteristics |
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Authors: | J Bastian J Courtright J Crawford |
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Institution: | (1) Department of Zoology, University of Oklahoma, 73019 Norman, OK, USA;(2) Parmly Hearing Institute, Loyola University, 6525 North Sheridan Road, 60626 Chicago, IL, USA |
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Abstract: | Extracellular injections of horseradish peroxidase were used to label commissural cells connecting the electrosensory lateral line lobes of the weakly electric fish Apteronotus leptorhynchus. Multiple commissural pathways exist; a caudal commissure is made up of ovoid cell axons, and polymorphic cells' axons project via a rostral commissure. Intracellular recording and labeling showed that ovoid cells discharge spontaneously at high rates, fire at preferred phases to the electric organ discharge, and respond to increased receptor afferent input with short latency partially adapting excitation. Ovoid cell axons ramify extensively in the rostro-caudal direction but are otherwise restricted to a single ELL subdivision. Polymorphic cells are also spontaneously active, but their firing is unrelated to the electric organ discharge waveform. They respond to increased receptor afferent activity with reduced firing frequency and response latency is long. Electrical stimulation of the commissural axons alters the behavior of pyramidal cells in the contralateral ELL. Basilar pyramidal cells are hyperpolarized and nonbasilar pyramidal cells are depolarized by this type of stimulation. The physiological results indicate that the ovoid cells participate in common mode rejection mechanisms and also suggest that the ELLs may function in a differential mode in which spatially restricted electrosensory stimuli can evoke heightened responses.Abbreviations ccELL
caudal commissure of the ELL
- CE
contralaterally excited
- DML
dorsal molecular layer
- ELL
electrosensory lateral line lobe
- EOD
electric organ discharge
- HRP
horseradish peroxidase
- IE
ipsilaterally excited
- MTI
mouth-tail inverted
- MTN
mouth-tail normal
- rcELL
rostral commissure of the ELL
- TRI
transverse inverted
- TRN
transverse normal |
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Keywords: | Electric fish Electroreception Commissural neurons Common mode rejection Sensory processing |
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