Visual responsiveness of central-complex neurons in the desert locust Schistocerca gregaria
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1
Philipps-University Marburg, Biology, Germany
The central complex (CX) of the insect brain comprises midline-spanning neuropils that play a role for motor control and visual integration, e.g. in visual place learning and spatial orientation. In desert locusts, CX neurons were shown to represent the electric field vector (E-vector) of polarized light which may serve navigational needs as E-vectors of skylight bear compass information. We combined intracellular recordings with tracer injections to characterize the responsiveness of CX neurons to object-like patterns of unpolarized light, a further class of visual signals crucial to spatial visual orientation. Particularly, we asked whether these responses may interact with polarization sensitivity.
All neurons considered here, including two novel cell types, showed robust E-vector-tuning when being stimulated by linearly polarized light through a slowly rotating polarizer. By contrast, at constant E-vectors responses were tonic in few cells while phasic in most. The latter abated within few seconds, indicating a fast shut-down of E-vector signalling under static stimulus conditions. Responses to translating bars were largely independent from specific object features and faded quickly in high-frequent presentations. This resembles habituative novelty- event detection rather than robust representation of object qualities. Presentation of sparse visual flow simultaneous to stimulation by polarized light with constant E-vector caused interactive effects in some cells, including first indications of a boosting effect of visual flow on polarization sensitivity.
Our data suggests a dependency of polarization signaling on exteroceptive context: in some cell types, representations of static E-vectors fade quickly while responsiveness is maintained under E-vector rotation, as related to rotational ego-motion in nature. In line with this, sparse visual flow boosted or maintained responses to polarized light with static E-vector in some cells.
Keywords:
insect vision,
central complex,
polarization vision,
visual flow,
context dependent
Conference:
International Conference on Invertebrate Vision, Fjälkinge, Sweden, 1 Aug - 8 Aug, 2013.
Presentation Type:
Poster presentation preferred
Topic:
Navigation and orientation
Citation:
Bockhorst
T and
Homberg
U
(2019). Visual responsiveness of central-complex neurons in the desert locust Schistocerca gregaria.
Front. Physiol.
Conference Abstract:
International Conference on Invertebrate Vision.
doi: 10.3389/conf.fphys.2013.25.00032
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Received:
21 Feb 2013;
Published Online:
09 Dec 2019.
*
Correspondence:
Mr. Tobias Bockhorst, Philipps-University Marburg, Biology, Marburg, Germany, tobias.bockhorst@biologie.uni-marburg.de