The Journal of Neuroscience, August 1, 2001, 21(15):5685-5692
Recurrent Network Interactions Underlying Flow-Field Selectivity
of Visual Interneurons
Juergen
Haag and
Alexander
Borst
Division of Insect Biology, Department of Environmental
Science, Policy, and Management, University of California, Berkeley,
California 94720-3112
Motion-sensitive large-field neurons found at higher processing
stages in many species often exhibit a remarkable selectivity for
particular flow fields. However, the underlying neural mechanisms are
not yet understood. We studied this problem in the so-called lobula
plate tangential cells (LPTCs) of the fly. Investigating the
connectivity between LPTCs by means of dual recordings, we find two
types of connections: (1) heterolateral connections between LPTCs of both hemispheres and (2) ipsilateral connections between LPTCs
within one lobula plate. The circuit is suitable to amplify incoming,
dendritic signals in the case of rotatory flow fields and to reduce
them in the case of other flow-field structures. In addition to
feedforward connectivity, thus, the flow-field selectivity of LPTCs may
be significantly attributable to recurrent excitation involving the
network of large-field neurons in both brain hemispheres.
Key words:
network interactions; motion detection; insect; vision; electrophysiology; dendrite
Copyright © 2001 Society for Neuroscience 0270-6474/01/21155685-08$05.00/0