Olfactory lateralization in homing pigeons: initial orientation of birds receiving a unilateral olfactory input.

It has been shown that homing pigeons (Columba livia) rely on olfactory cues to navigate from unfamiliar locations. In fact, the integrity of the olfactory system, from the olfactory mucosa to the piriform cortex, is required for pigeons to navigate over unfamiliar areas. Recently it has been shown that there is a functional asymmetry in the piriform cortex, with the left piriform cortex more involved in the use of the olfactory navigational map than the right piriform cortex.

Functional asymmetry of left and right avian piriform cortex in homing pigeons' navigation.

It has been shown that homing pigeons rely on olfactory cues to navigate over unfamiliar areas and that any kind of olfactory impairment produces a dramatic reduction of navigational performance from unfamiliar sites. The avian piriform cortex is the main projection field of olfactory bulbs and it is supposed to process olfactory information; not surprisingly bilateral lesions to this telencephalic region disrupt homing pigeon navigation. In the present study, we attempted to assess whether the left and right piriform cortex are differentially involved in the use of the olfactory navigational map.

Factors reducing the expected deflection in initial orientation in clock-shifted homing pigeons.

To orient from familiar sites, homing pigeons can rely on both an olfactory map and visual familiar landmarks. The latter can in principle be used in two different ways: either within a topographical map exploited for piloting or in a so-called mosaic map associated with a compass bearing. One way to investigate the matter is to put the compass and the topographical information in conflict by releasing clock-shifted pigeons from familiar locations.

Hippocampal lesions do not disrupt navigational map retention in homing pigeons under conditions when map acquisition is hippocampal dependent.

In contrast to map-like navigation by familiar landmarks, understanding the relationship between the avian hippocampal formation (HF) and the homing pigeon navigational map has remained a challenge. With the goal of filling an empirical gap, we performed an experiment in which young homing pigeons learned a navigational map while being held in an outdoor aviary, and then half the birds were subjected to HF ablation. The question was whether HF lesion would impair retention of a navigational map learned under conditions known to require participation of HF.

Bilateral participation of the hippocampus in familiar landmark navigation by homing pigeons.

Recent findings indicate a different role of the left and right hippocampal formation (RHF) in homing pigeon navigational map learning. However, it remains uncertain whether the left or the RHF may play a more important role in navigation based on familiar landmarks. In the present study, we attempted to answer this question by experimentally releasing control and left and right hippocampal ablated pigeons from familiar training sites under anosmia, to render their navigational map dysfunctional, and after a phase-shift of the light-dark cycle, to place into conflict a pilotage-like landmark navigational strategy and a site-specific compass orientation landmark navigational strategy.

Effects of monocular viewing on orientation in an arena at the release site and homing performance in pigeons.

Orientation and homing performance of pigeons with the left or right eye occluded were assessed in an arena at the release site and during the subsequent homing flight. Three release sites near Pisa, Italy, were used. Compared to binocular controls, monocular birds showed a bias in orientation towards the side of the viewing eye.