Archive for the ‘Papers from 2010’ Category

The impact of noise on models of path integration

Opening the black box to see how brains perform path integration (PI) is out of reach of our current techniques. To better understand fundamental processes like path integration requires a creative touch with analytical and experimental approaches; Rob Vickerstaff and Allen Cheung have taken a modelling approach to their studies of PI. By assessing the impact of noise on various models of PI, they are able to rate the robustness of various co-ordinate frames for PI – surely a major factor in rating their biological plausibility.

Cheung A, Vickerstaff R, 2010 Finding the Way with a Noisy Brain. PLoS Comput Biol 6(11): e1000992. doi:10.1371/journal.pcbi.1000992

Categories: Papers from 2010

Sensitivities of the Sandhopper eye

A recurring theme of posts here is that an understanding of behaviour requires knowledge of (amongst other things) the sensory apparatus available to the navigating animal. Ugolini et al add to their extensive studies of the Sandhopper with a characterisation of the spectral photoresponses of its compound eyes. A strong UV-blue sensitivity is confirmed, which may be the channel for celestial compass information. Allied with a green channel, this is likely to provide the sandhopper with a visual system ideally suited for identifying terrestial landmarks, the use of which has been previously demonstrated by this group.

Ugolini A, Borgioli G, Galanti G, Mercatelli L, Hariyama T. (2010) Photoresponses of the compound eye of the sandhopper Talitrus saltator (Crustacea, Amphipoda) in the ultraviolet-blue range. Biol Bull. 2010 Aug;219(1):72-9.

Categories: Papers from 2010

Towards an understanding of spatial memory in Drosophila

Being able to genetically dissect the brain process and structures involved in insect spatial behaviour would be a massive opportunity for our research field.  This research requires the correct behavioural assays to probe spatial behaviour and it is this endeavour that leads Foucaud et al (2010) to develop an analog of the water maze for Drosophila.

Foucaud J, Burns JG, Mery F (2010) Use of Spatial Information and Search Strategies in a Water Maze Analog in Drosophila melanogaster. PLoS ONE 5(12): e15231. doi:10.1371/journal.pone.0015231

Categories: Papers from 2010

Natural landmarks and route learning

Foragers of the Australian desert ant Melophorus bagoti are well known to develop individual stereotypical routes through their naturally cluttered environment. Wystrach et al. investigated the mechanisms of route following by designing artificial and manipulable obstacle courses made out of natural objects such as logs, branches and tussocks.

Antoine Wystrach comments:

“The experiment reveals that more ants developed a stereotypical route when the route-objects were bigger and the gaps chosen between obstacles  seemed to result from the direction dictated by the path integrator. By inter-changing the objects’ position, we showed that the ants could memorise and ‘recognise’ the familiar landmarks along their route, although removing them did not prevent the ants homing  efficiently. Further manipulations also revealed a strong link between the use of route-landmarks and the rest of the visual panorama. We think this link may be the result of the use of panoramic views, encompassing both route-landmarks and distal panorama.”

Wystrach, A., Schwarz, S., Schultheiss, P., Beugnon, G. and Cheng, K. (2010). Views,landmarks, and routes: how do desert ants negotiate an obstacle course? J. Comp.Physiol. A

Categories: Papers from 2010

Egocentric chicks…

There is a gap in the literature between insect and vertebrate navigation. This gap seems to result more from the use of different approaches and a lack of comparative studies than from actual differences in the animals’ navigational mechanisms. The recent study of Pecchia et al. provides a bridge between vertebrate and insect cognition by demonstrating the use of an egocentric view-based strategy in chicks.
The authors trained chicks to relocate a reward within a rectangular array of 4 cylindrical landmarks. The reward was located inside one of the landmarks and could be reached through a head-sized circular opening in the cylinder. Chicks could learn the spatial arrangements of the landmark scene as long as the circular opening pointed in the same direction throughout training, but failed if the circular opening was rotated around the rewarded landmark from trial to trial. Interestingly, the learning of the rewarded landmark identity was not affected by such rotation of the circular opening. The authors conclude that a stable view at the goal is required for “place navigation” (i.e., learning of the landmarks’ spatial arrangement) but not for “non-spatial learning” (i.e., individuallandmark recognition).    Post by Antoine Wystrach

Pecchia, T. and Vallortigara, G. (2010). View-based strategy for reorientation bygeometry. J. Exp. Biol. 213, 2987-2996.

Categories: Papers from 2010

Coming in from the heat

The cost of searching for an inconspicuous nest entrance in the scorching heat is all the incentive that a desert ant needs to rapidly learn any landmark information that is available. In this paper Wehner and Muller show how even a single pebble can decrease time spent searching for the nest by a factor of 5 or more.  Wehner and Muller go on to investigate how searching time relates to the direction of nest approach when a nest is marked by two artificial cylinders.  They find that searching time is lowest (i.e. most accurate return) when ants inbound route goes close to a landmark, thus generating the largest change in retinal appearance of the landmarks during the final approach. These final routes are smooth and the paper throws up fascinating questions about how smooth inbound routes might be guided by discrete views stored during the learning walks of these ants. The learning walks were described in a paper earlier in the year (re-posted below).

Rüdiger Wehner and Martin Müller (2010) Piloting in desert ants: pinpointing the goal by discrete landmarks J Exp Biol 213, 4174-4179

Categories: Papers from 2010

Learning walks in ants.

Muller and Wehner have described a fascinating behaviour in their recent Current Biology paper (“Path Integration Provides a Scaffold for Landmark Learning in Desert Ants”). Outbound foragers perform a series of pirouettes that seem structured in order to fixate their nest entrance.

Muller and Wehner (2010) Current Biology, Volume 20, Issue 15, 1368-1371,

As a follow up to the paper, Graham et al. discuss the ways that path integration and snapshots could be combined.

Paul Graham, Andrew Philippides, Bart Baddeley (2010) Animal Cognition: Multi-modal Interactions in Ant Learning. Current Biology, 20(15), R639-R640
Categories: Papers from 2010