Publikationsserver
Coding of sky-compass information in neurons of the anterior optic tubercle of the desert locust Schistocerca gregaria
The primary aim of my Doctoral thesis project was to test through intracellular recordings the hypothesis that the lower unit of the AOTu participates in polar- ization vision. Four types of interneurons with ramifications in the lower unit of the AOTu were characterized in multiple recordings...
Saved in:
| Main Author: | |
|---|---|
| Contributors: | |
| Format: | Doctoral Thesis |
| Language: | German |
| Published: |
Philipps-Universität Marburg
2006
|
| Subjects: | |
| Online Access: | PDF Full Text |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | The primary aim of
my Doctoral thesis project was to test through
intracellular recordings the hypothesis that the
lower unit of the AOTu participates in polar-
ization vision. Four types of interneurons with
ramifications in the lower unit of the AOTu were
characterized in multiple recordings. All of these
neurons were sensitive to polarized light, sub-
stantiating our hypothesis (Chapter I, -> page
19). Two types of neuron, called lobula tuber-
cle neuron (LoTu1) and tubercle tubercle neuron
(TuTu1), were especially amenable to intracel-
lular recordings, due to their large axon diam-
eters. In the first set of experiments, we found
that all polarization-sensitive neurons were also
responsive to unpolarized light (Chapter I, -> page 19).
To investigate the significance of this
finding, we extended the stimulation with un-
polarized light in a second set of experiments.
The responses of both LoTu1 and TuTu1 to UV
and green light spots from different directions
suggest that these neurons signal the horizontal
direction of the sun (solar azimuth), by exploit-
ing both intensity- and color-gradients as well
as the sky-polarization pattern (Chapter II, -> page 35).
The use of both unpolarized and po-
larized light information to detect the solar az-
imuth can result in conflicting information pro-
vided by the different cues. One way to reduce
this conflict of information is to exclude certain
areas of polarized skylight from being analyzed
by the polarization-vision system. By stimulat-
ing with different degrees of polarization (d), we
showed that the threshold for E-vector detec-
tion lies around d-values of 0.3. This means
that an area of around 100 degrees around the sun con-
tains no visible E-vector information for these
neurons (Chapter III, -> page 51). Recent be-
havioral experiments further confirmed that the
pathway described above is vital for polarotaxis
in locusts. Tethered locusts that are flown under
a slowly rotating polarizer show periodic changes
in yaw torque with a period of 180 degrees (Mappes &
Homberg, 2004). When the anterior optic tract
is unilaterally transected, the locusts are still
able to respond to the rotating E-vector in the
same manner as intact animals. However, when
the DRA that is contralateral to the transection
site is occluded, the animals become disoriented
(Mappes and Homberg, in revison). |
|---|---|
| Physical Description: | 105 Pages |
| DOI: | 10.17192/z2006.0517 |