2. Behavioral Biology TALKS - Deutsche Zoologische Gesellschaft

����5 Nicole Prinz
The influence of ∆9-tetrahydrocannabinol administration on retrieval of spatial
memory in the zebrafish (Danio rerio)
Authors: Nicole Prinz 1 , Tim Ruhl 1 , Gerhard von der Emde 1
Affiliation: 1 Institute of Zoology, Department of Neuroethology/ Sensory Ecology,
University of Bonn
While spatial memory has been intensely investigated in mammals, such as in mouse
or in rats, little focus was set on the spatial memory of lower vertebrate, such as fish.
Spatial memory in teleost fish is thought to be located in the dorsolateral area of the
caudal telencephalon. This area appears to be homologue to the hippocampal
formation, which has been identified as the center of spatial memory formation in
mammals. In these regions, the density of ?9-tetrahydrocannabinol (THC) sensitive
CB1 receptors is very high in both fish and mammals. CB1 as well as CB2 receptors
belong to the endocannabinoid system of vertebrates and are activated by
cannabinoids. We therefore conclude that the endocannabinoid system might
influence spatial memory in fish, like it does in mammals.
We used the tropical freshwater fish, Danio rerio, and examined the influence of the
pharmacologically-active substance THC on this fish`s spatial memory.
Fish had to learn the position of a small food item in an open-field maze by using an
ego-allocentric orienting strategy. With termination of the acquisition phase and
memory consolidation, THC was administered and its effect on retrieval of memory
was tested. Within 14 days, the latency to find the reward decreased from an
average of about 90s to about 10s, indicating that the fish had learned the position of
the reward. Two hours in water with THC (0,0314µg/l) led to an increase in search
times to about 50s, i.e. near pre-training levels. Thus we conclude that the activation
of CB1 receptors has a strong influence on retrieval and functional aspects of spatial
memory in zebrafish.
����6 Theodora Fuss
Do sharks have a cognitive spatial map?
Authors: Theodora Fuss 1 , Horst Bleckmann 1 , Vera Schluessel 1
Affiliation: 1 Universität Bonn, Institut für Zoologie, Abteilung für vergleichende
Neurobiologie
This study assessed spatial learning and memory in the grey bamboo shark
(Chiloscyllium griseum) and the coral cat shark (Atelomycterus marmoratus). As
complex spatial memory functions, including a cognitive spatial map, had already
been described in stingrays (Potamotrygon motoro, Schluessel & Bleckmann 2005) it
was hypothesized that sharks can also learn and apply an allocentric orientation
strategy. Eight out of twelve sharks reached the learning criterion of 70% correct
choices on three consecutive sessions in a two choice alternative spatial task based
on allocentric strategies. Seven different types of Transfer tests revealed that sharks
predominantly used visual cues to complete the task, thereby constructing a
cognitive spatial map of their surroundings. These results correspond to earlier
studies on stingrays (Schluessel & Bleckmann 2005), goldfish (Carassius auratus, Salas
et al 1996) and mammals (O'Keefe & Nadel 1978, Gallistel 1990). Assuming that
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