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Prof. Dr. Martin Giurfa new address: Centre de Recherches sur la Cognition Animale CNRS - Université Paul Sabatier-Toulouse III 118 Route de Narbonne 31062 Toulouse cedex 4 FRANCE phone: 0033 561 55 67 33fax: 0033 561 55 61 54e-mail: giurfa@cict.fr |
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1) Detection and recognition of coloured stimuli by honeybees (funded by
the German Research Council – DFG Me-Giu 365/20-2)
The purpose of this project is to study how spectral
parameters affect the detection of colour stimuli by
free-flying honeybees. We have established the minimal visual angle that a
spectral stimulus should subtend in order to be detected, and determined that bees
make use of their colour vision system as well as a green-receptor based
achromatic system for the detection of coloured targets. The minimum visual angle required for detection of a
coloured stimulus is 15° if the stimulus presents chromatic contrast but no
green contrast, whilst it is 5° if it presents both kinds of contrast.
Both systems are alternatively used depending on the visual angle subtended by
the targets at the bee’s eye: at larger visual angles (>15°) bees use the
chromatic properties of the targets; at smaller ones (ca. 5°) they use the
achromatic green contrast. Our results enable
to relate detection capabilities of Hymenoptera with
different signalling strategies of flowers and also to characterize the
neural elements involved in such a task. These studies are performed in collaboration
with Dr. M. Vorobyev and Natalie
Hempel de Ibarra.
2) Symmetry perception in honeybees: abstraction and concept formation
in simple nervous systems (funded by the German Research Council – DFG
Giu 291/3-1)
The purpose of this project is to examine a
honeybee's capability to develop a concept of bilateral symmetry. We showed
that bees may be trained to discriminate bilaterally symmetric from non-symmetric
patterns and that they can transfer the task accordingly to novel stimuli. This
demonstrates a perceptual capacity to detect symmetric vs. asymmetric patterns
and raises the question of whether bees can categorise patterns according to
their symmetric or asymmetric outline. The question of whether organisms with
relatively simple nervous systems can abstract rules related to the problem of
symmetry recognition from multiple learning sets is relevant since it relates
not only to the level of perception but also to that of their cognitive
abilities. These studies were performed in collaboration with Nina Müller-Deisig.
3) The Importance of Mushroom bodies for Higher-order Multimodal
Computations in Insects (funded by the German
Research Council – SFB 515 – Project C7 and by Procope 2000 – Cooperation with
INRA, Paris, France)
The mushroom bodies (MB) constitute the most
obvious and voluminous structures in the insect brain. Each MB consists of two
fused symmetrical substructures of about 170,000 tightly packed neurones, the
Kenyon cells. Such neurones receive their input in the calyx region and project
two collaterals to the a- and b-lobe, the
output regions of the MB. The calyx region is subdivided into 3 major input
areas (lip, collar and basal ring) that receive input from different sensory
pathways: olfactory projection neurones connecting the antennal lobe with the
mushroom bodies project to the lip but not to the collar whereas visual
projection neurones from the medulla and the lobula project to the collar
exclusively. Such a compartmentalisation of the MB inputs suggests separated
processing of visual and olfactory signals. Since MB output neurones are
clearly multimodal, integration of these signals should also occur at the MB
level.
The objective of our research program is to
analyse the functional role of the insect MBs. To that aim we combine training
procedures in different learning contexts with selective MB ablation by means
of application of hydroxyurea at the early larval stage. Such an ablation
technique has been already established in our laboratory by Dr. Dagmar Malun. It allows to test specifically whether
MB-ablated bees are capable of performing certain tasks pertaining to different
learning contexts as well as intact bees do. Particularly, we raise the
question of whether the MBs provide a neuronal substrate for higher-order
multimodal computations and context-based, configural associations. Patterning
experiments with intact and ablated bees are performed to answer this question
(see Nina Müller Deisig and Bernhard
Komischke).
Methods and
Interests
Our work is mainly based on behavioural and
psychophysical methods. Behavioural experiments with bees are performed to
determine learning and discrimination capabilities. Different set ups where the
behaviour of the bees is carefully controlled and recorded are used to that
aim. The psychophysical approach allows to propose specific models on the
visual processing and to test them in appropriate behavioural experiments.
Selected
Publications
[1] Giurfa M, Núñez J, Backhaus W (1994) Odour
and colour information in the foraging choice behaviour of the honeybee.
Journal of Comparative Physiology A 175:773-779.
[2] Giurfa M, Backhaus W, Menzel R (1995) Color
and angular orientation in the discrimination of bilateral symmetric patterns
in the honeybee. Naturwissenschaften 82:198-201.
[3] Giurfa M, Núñez J, Chittka L, Menzel R
(1995) Colour preferences in flower-naive honeybee foragers. Journal of
Comparative Physiology A 177:247-259.
[4] Giurfa M, Vorobyev M, Kevan P, Menzel R
(1996) Detection of coloured stimuli by honeybees: minimum visual angles and
receptor specific contrasts. Journal of Comparative Physiology A
178:699-709
[5] Giurfa M, Eichmann B,
Menzel R (1996) Symmetry perception in an insect. Nature 382:458-461.
[6] Giurfa M (1996) Movement patterns of
honeybee foragers: motivation and decision rules dependent on the rate of
reward. Behaviour 133:579-596
[7] Giurfa M, Vorobyev M, Brandt R, Posner B,
Menzel R (1997) Detection and discrimination of
coloured stimuli by honeybees: alternative use of achromatic and chromatic
signals. Journal of Comparative Physiology A 180:235-244.
[8] Giurfa M, Menzel R (1997) Insect visual
perception: complex abilities by simple nervous systems. Current Opinion in
Neurobiology 7:505-513.
[9] Giurfa M, Vorobyev M (1998) The angular
range of achromatic target detection by honeybees.
Journal of Comparative Physiology A 183:101-110.
[10] Giurfa M, Hammer M, Stach S, Stollhoff N,
Müller-Deisig N, Mizyrycki C (1998) Pattern learning by honeybees: conditioning
procedure and recognition strategy. Animal Behaviour 57:315-324.
[11] Giurfa M, Capaldi E (1999)
Vectors, routes and maps: new discoveries about navigation in insects. Trends in Neurosciences 22:237-242.
[12] Menzel R, Giurfa M (1999) Cognition by a
mini brain. Nature 400:718-719.
[13] Giurfa
M, Dafni A, Neal PR (1999) Floral symmetry and its role in plant pollinator
systems. International Journal of Plant Sciences 160:541-550.
[14] Giurfa, M, Zaccardi G, Vorobyev M
(1999) How do bees detect coloured targets using different regions of their
compound eyes. Journal
of Comparative Physiology A 185:591-600.
last update: 28 Jan 2003
