The Journal of Neuroscience, February 1, 2002, 22(3):1114-1125
Neurons of the Central Complex of the Locust Schistocerca
gregaria are Sensitive to Polarized Light
Harm
Vitzthum1,
Monika
Müller1, and
Uwe
Homberg2
1 Institut für Zoologie, Universität
Regensburg, D-93040 Regensburg, Germany, and 2 Fachbereich
Biologie, Tierphysiologie, Universität Marburg, D-35032 Marburg,
Germany
The central complex is a topographically ordered neuropil structure
in the center of the insect brain. It consists of three major
subdivisions, the upper and lower divisions of the central body and the
protocerebral bridge. To further characterize the role of this brain
structure, we have recorded the responses of identified neurons of the
central complex of the desert locust Schistocerca
gregaria to visual stimuli. We report that particular types of
central complex interneurons are sensitive to polarized light. Neurons
showed tonic responses to linearly polarized light with spike discharge
frequencies depending on e-vector orientation. For all
neurons tested, e-vector response curves showed
polarization opponency. Receptive fields of the recorded neurons were
in the dorsal field of view with some neurons receiving input from both compound eyes and others, only from the ipsilateral eye. In addition to
responses to polarized light, certain neurons showed tonic spike
discharges to unpolarized light. Most polarization-sensitive neurons
were associated with the lower division of the central body, but one
type of neuron with arborizations in the upper division of the central
body was also polarization-sensitive. Visual pathways signaling
polarized light information to the central complex include projections
via the anterior optic tubercle. Considering the receptive fields of
the neurons and the biological significance of polarized light in
insects, the central complex might serve a function in sky
compass-mediated spatial navigation of the animals.
Key words:
polarized light; polarization vision; central complex; compass navigation; head direction; insect brain; locust; Schistocerca gregaria
Copyright © 2002 Society for Neuroscience 0270-6474/02/2231114-12$05.00/0
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