Learning to navigate – how desert ants calibrate their compass systems

Abstract

Navigating through the environment is a challenging task that animals cope with on a daily basis. Many animal species have impressive capabilities to navigate in complex or even harsh environments. Cataglyphis desert ants are a famous example. These ants use a remarkable navigational repertoire to find their way home after far-reaching foraging trips. How do naïve ants calibrate their visual navigational systems? The ants perform stereotyped sequences of learning walks before switching from tasks inside the darkness of their nest, to foraging under bright sunlight. Here, naïve ants align nest-directed views using the earth’s magnetic field as a compass reference. Neuronal plasticity was mapped in two visual pathways to higher brain centers during this transition. Both their first exposure to light, and the performance of learning walks lead to distinct changes in synaptic circuits along both visual pathways, reflecting calibration and memory formation in the ants’ visual compass systems.

Analysis of Synaptic Microcircuits in the Mushroom Bodies of the Honeybee

“…A similar effect has also been demonstrated in leaf-cutting ants in regards to the associative (aversive) olfactory learning of odors associated with the formation of an olfactory LTM for detecting unsuitable plant materials [19]. Similarly, in the visual system, experience in naïve Cataglyphis desert ants during first learning walks (when ants learn and memorize visual information about panoramic landmarks) has been shown to trigger an increase of MG in the visual compartments (collar) of the MB calyx [20,82,83]. These increases in densities of PN synaptic boutons seen after associative LTM formation suggest the formation of learning-related (Hebbian) structural plasticity in MB-calyx circuits (Figure 3).…”

“…These increases in densities of PN synaptic boutons seen after associative LTM formation suggest the formation of learning-related (Hebbian) structural plasticity in MB-calyx circuits (Figure 3). In contrast to the learning-related increase of PN boutons, pruning of PN boutons upon non-associative (first) sensory exposure most probably represents a form of homeostatic plasticity, adjusting MB input circuits to a drastically changing sensory input during the interior-exterior transition (Figure 3; see also [83]; also reviewed in [20]).…”

Modelling the emergence of cognitive styles

“…However, of course, many other aspects of the environment and the species living in it are likely to influence the evolution and development of cognitive styles. For example, instead of handling resources, other environmental aspects may need to be learned, such as navigation through space [40], or nest-building [41]. Also, when interacting with conspecifics, cognitive styles may strongly be influenced by social learning skills.…”

Kompass im Kopf

“…Damit konnten relevante Stimuli identifiziert und zeitlich‐räumliche Bedingungen für die Kalibrierung der Navigationssysteme mittels Manipulation getestet werden. Die quantitativen Verhaltensanalysen in ökologisch relevantem Kontext haben wir mit Labormessungen zur strukturellen synaptischen Plastizität in visuellen Schaltkreisen im Ameisengehirn kombiniert .…”

“…Der Übergang vom Innendienst zum Außendienst führt zu strukturellen Veränderungen an synaptischen Verschaltungen in zwei visuellen Bahnen im Gehirn von Cataglyphis (Abbildung ). Dies konnten wir anhand von ▸ immunohistochemischen Markierungen und anschließenden computergestützten 3D‐Rekonstruktionen ermitteln . Hierzu werden die Gehirne zuvor mit Hilfe eines ▸ Laserrastermikroskops mit hoher Auflösung eingescannt.…”