Local geometric properties do not support reorientation in hippocampus-engaged homing pigeons.

Abstract

It is generally accepted that the geometry of an environment is a reliable source of information for spatial navigation used by most vertebrate species. However, there is a continuing debate on which geometrical properties of space are the ones that matter for reorientation. In this study, pigeons were trained to find a food reward hidden in 2 opposite corners in a rectangular arena. The animals were then tested in a kite-shaped environment similar to Pearce, Good, Jones, and McGregor (2004). We found that pigeons, unlike rats, were not able to identify the correct corner in the kite arena even though elements clearly preserved the correct long wall-short wall geometric configuration and the local aspect of the trained goal. This behavioral study was followed by a c-Fos, IEG analysis of brain activation that contrasted pigeons exposed to the trained, familiar rectangular environment with pigeons that were exposed to an unfamiliar, trapezoid arena. The hippocampal formation (HF) displayed greater c-Fos expression in the animals exposed to the familiar, training arena, which further supports the conclusion that pigeons do not substantially rely on local geometric features for reorientation.

Spontaneous object-location memory based on environmental geometry is impaired by both hippocampal and dorsolateral striatal lesions

“…However, our results also raise the question of why Sotelo et al (2019) were unable to replicate Pearce et al's (2004) findings, but still found c-Fos activation in the HPC. In terms of the use of local geometry, the use of an appetitive task may have had an effect.…”

“…While experiments with rats seemed to indicate that the HPC was necessary for representing local geometric features, such as the configuration of long and short walls in a particular corner (e.g. Jones et al, 2007; McGregor et al, 2004; Pearce et al, 2004), recent research in pigeons (Sotelo et al, 2019) casts doubt on this conclusion because pigeons showed no transfer between environments based on local geometry, but hippocampal c-Fos analysis indicated hippocampal activity when pigeons experienced transfer to a familiar overall shape. Importantly, the SOR procedure used in our experiments removes the confound of the nature of the motivational demands of the procedure since the pigeon study used an appetitive procedure, while the rat studies used an aversive motivation.…”

“…Therefore, the role of the HPC in learning based on local or global geometry remains uncertain. One difference between Pearce et al (2004) and Sotelo et al (2019), other than the species tested, was the use of appetitive and aversive procedures, which could have altered the way the animals behaved (Golob and Taube, 2002). To remove the confound of motivational reinforcer, we employed a spontaneous object recognition (SOR) version of a geometry learning task (Experiment 1).…”

“…However, there is evidence of both global and local geometry controlling spatial behaviour in pigeons (Bingman et al, 2006), chicks (Kelly et al, 2011) and humans (Lew et al, 2014; Sturz et al, 2012). Sotelo et al (2019), based on Pearce et al (2004), trained pigeons to locate a reinforcer in one corner of a rectangular arena before transferring them to a kite shape, in which two corners shared the same local geometric properties as the corners in the rectangle. Unlike Pearce et al (2004), who found transfer of rats’ search between environments, there was no evidence that pigeons recognised the matching local geometry between the two arenas, despite learning the correct location within the rectangle.…”

What Suboptimal Choice Tells Us About the Control of Behavior

“…however, recent research questions the evidence for both the local geometry account and the principal/medial axes accounts. Sotelo, Nardi, et al (2019) with pigeons, and Sotelo, Alcalá, Bingman, and Muzio (2019) with a terrestrial toad, employed a similar transformation design as Pearce et al (2004) and failed to find any evidence that either species was able to transfer their search from a rectangle to a kite. The results are difficult to explain without assuming that during training in the rectangle, the pigeons and toads had formed the kind of global geometric representation assumed by Cheng and Spetch (1998) to underlie Cheng's (1986) findings.…”