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Archive for the ‘Papers from 2014’ Category

Interaction of navigational cues

It is now clear that the outputs of different navigational modalities are simultaneously influencing the behaviour of navigating ants, but we don’t know the details of how this is implemented. In these new experiments Legge et al investigate this process. They confirm the previous result that ants will choose an intermediate direction when PI and learnt visual cues are discrepant, going further they show that the weighting shifts towards learnt views when those views are more informative. An interesting side note is that ants continue to integrate the cues even when the cues predict discrepant directions. This may represent a failure of the ants’ cue integration heuristic. Generally, it is considered optimal to choose one or other cue when they are very different.

Legge, E. L., Wystrach, A., Spetch, M. L., & Cheng, K. (2014). Combining sky and Earth: Desert ants (Melophorus bagoti) show weighted integration of celestial and terrestrial cues. The Journal of experimental biology, jeb-107862.

Categories: Papers from 2014

Selective attention during pattern recognition

Visual attention is something that we take for granted, i.e our ability to focus on components of a larger scene. The existence of visual attention has been demonstrated for insects, however we don’t know much about the implementational detail of visual attention within complex behaviour. Avarguès-Weber et al have begun to study this using a classic problem: can one “see the wood for the trees”. Bees are trained with compound patterns where the global shape (a square for example) is made up of smaller shapes (e.g. triangles). Bees will subsequently prefer the global shape made up of new smaller shapes over a new global shape made up of the original smaller shape. However, this preference can be reversed if bees have pre-training experience of small shapes. Thus in their behavioural choices bees show a form of flexible visual attention. Further investigations of the balance of the cognitive and behavioural mechanisms that build to this selective attention are needed.

Aurore Avarguès-Weber, Adrian G. Dyer, Noha Ferrah, and Martin Giurfa (2014) The forest or the trees: preference for global over local image processing is reversed by prior experience in honeybees. Proc. R. Soc. B. doi:10.1098/rspb.2014.2384
Categories: Papers from 2014

Motion and the brain

Here are a pair of articles from the Bielefeld group. This group has, for many years, been looking at the perception of motion information for behaving animals in natural environments. Egalhaaf et al. provide a review of motion computation in the insect brain and how it is adapted to constraints of an insect’s behavioural requirements and environmental constraints. Schwegmann et al. present new data: a natural image statistics analysis of the information available to flying insects during their saccadic flight paths. It is found that rotations cause very large changes to images across brightness, contrast and spatial frequency. Translations only result in significant changes when there are nearby objects. These results, using natural images, align with the intuitive differences in visual input one would expect during rotation and translation. Taken together, we see the value in considering the visual systems of animals as part of the interaction between behaviour and the natural world.

Schwegmann A, Lindemann JP, Egelhaaf M (2014) Temporal Statistics of Natural Image Sequences Generated by Movements with Insect Flight Characteristics. PLoS ONE 9(10): e110386. doi:10.1371/journal.pone.0110386

Egelhaaf M, Kern R and Lindemann JP (2014) Motion as a source of environmental information: a fresh view on biological motion computation by insect brains. Front. Neural Circuits 8:127. doi: 10.3389/fncir.2014.00127

Categories: Papers from 2014

Guiding multi-segment routes.

Many navigation studies treat an insect forager’s task as simply shuttling between two locations (nest and feeder). Of course natural foraging might often involve multiple locations with insects having to learn multi-segment routes. Najera et al. investigate the cues that bees might use to to set a direction to a second patch of food after visiting an initial patch. They show that bees can use information from celestial compass cues and also from terrestrial ‘landmarks’ to set the appropriate direction. Thus the local vectors produced in this context are based on redundant information.

Najera, D. A., McCullough, E. L., & Jander, R. (2014). Honeybees Use Celestial and/or Terrestrial Compass Cues for Inter‐Patch Navigation. Ethology.

Categories: Papers from 2014

How might landmark information be encoded in the brain?

In recent years the field of insect navigation has benefited greatly from considering the information that is available in real world visual scenes. However we very little idea about how visual information (for navigation tasks) may be encoded in the brain. Over a series of papers the Bielefeld team have shown how motion cues might be used for visual guidance. Here they go into the brain and demonstrate that motion information from landmarks is encoded in the responses of wide field cells in the bee’s lobula. Movies of natural ‘bee’s eye’ scenes were created from recordings of the learning flights of bumblebees and a Virtual Reality reconstruction of the experimental set-up. The ‘bee-eye’ movies were played to tethered bees and recordings showed that proximal landmarks create a stable motion signature irrespective of the texture of the landmarks (i.e. even if they are camouflaged). Therefore these neurons provide a signal that could be used for view-based homing.

Mertes, M., Dittmar, L., Egelhaaf, M., & Boeddeker, N. (2014). Visual motion-sensitive neurons in the bumblebee brain convey information about landmarks during a navigational task. Frontiers in Behavioral Neuroscience8, 335.
Categories: Papers from 2014

Bumble vs honey

Bumblebees and honeybees are closely related but they do show behavioural differences in colony organisation and foraging style. Sherry and Strang ask whether these differences might be accompanied be differences in cognition across species. The paper acts as a handy review of the behavioural assays by which people have probed bee cognition and as much as anything the review is useful in highlighting gaps in our knowledge. With regard to cognitive differences, the most reliable effect seems to be the bumblebee’s greater flexibility which matches a more generalist foraging style.

Sherry, D. F., & Strang, C. G. (2014). Contrasting styles in cognition and behaviour in bumblebees and honeybees. Behavioural processes.

Categories: Papers from 2014

Do walking bees navigate like ants?

One thing that many research groups are working towards is the idea of recording from insect brains as they undertake navigation. One approach is to use VR whilst animals move on a trackball, another is to have walking animals in a small arena. Jin et al. are working towards the latter idea by developing a visual navigation assay for walking bumblebees. In this experiment bees learn to find sucrose on a coloured patch on the floor, within a room that has visual cues on the wall. In tests, bees are tracked as they search for the now absent food. If the coloured patch is present then bees show a strong bias for searching at that location. However if the coloured patch is absent there is only a tiny bias for the quadrant of the arena defined by the “panoramic” visual cues. Thus, for me, the title of the paper is a little hasty in suggesting that bumblebees memorize the panorama. Perhaps a more salient panorama (using back-lit contrast rather than simple shapes) would evoke a stronger effect.

Jin, N., Landgraf, T., Klein, S., & Menzel, R. (2014). Walking bumblebees memorize panorama and local cues in a laboratory test of navigation. Animal Behaviour97, 13-23.
Categories: Papers from 2014