Seeing the Forest for the Trees, and the Ground Below My Beak: Global and Local Processing in the Pigeon’s Visual System

Abstract

Non-human animals tend to solve behavioral tasks using local information. Pigeons are particularly biased toward using the local features of stimuli to guide behavior in small-scale environments. When behavioral tasks are performed in large-scale environments, pigeons are much better global processors of information. The local and global strategies are mediated by two different fovea in the pigeon retina that are associated with the tectofugal and thalamofugal pathways. We discuss the neural mechanisms of pigeons’ bias for local information within the tectofugal pathway, which terminates at an intermediate stage of extracting shape complexity. We also review the evidence suggesting that the thalamofugal pathway participates in global processing in pigeons and is primarily engaged in constructing a spatial representation of the environment in conjunction with the hippocampus.

Visual categories and concepts in the avian brain

“…These findings suggest that some components of the primate visuo-spatial system, PFC and extended memory systems that enable higher-order object recognition abilities (e.g., “mental rotation” and view interpolation) do not have equivalents in the pigeon brain. As we will discuss when we turn our attention to the avian visual cortex, these findings align with the neurophysiological data suggesting that the pigeon visual system represents object features at an intermediate stage of complexity relative to primates (Clark and Colombo 2022 ; Clark et al 2022a ). We here use the term “avian visual cortex” to label the isocortex-like pallial components of the visual thalamofugal and tectofugal pathways (Stacho et al 2020 ).…”

“…To facilitate the fine-grained analysis of objects features, the avian retina is equipped with two specialized regions of high cone and ganglion cell densities to enhance spatial and temporal resolution (Bringmann et al 2018 ). These two areas have different projections to neural structures and enable distinct analyses of the visual input (Remy and Güntürkün 1991 ; Güntürkün and Hahmann 1999 ; Clark and Colombo 2022 ). The avian tectofugal pathway—homologous to the mammalian extrageniculocortical pathway—is mainly responsible for both object and motion vision in the frontal visual field: As depicted in Fig.…”

“…Fig. 1 B; Güntürkün and Hahmann 1999 ; Remy and Güntürkün 1991 ) that has a bias for local processing of object features (Clark and Colombo 2022 ). In contrast, the thalamofugal pathway seems to participate in global processing of more distant objects in the surrounding of pigeons (Clark and Colombo 2022 ).…”

Spatial cognition and the avian hippocampus: Research in domestic chicks

“…In contrast, "non-geometric information" is a property that cannot be defined by relative position, such as the local features of the goal itself (Gallistel, 1990). In chicks, this information is processed outside the hippocampus, e.g., in the medial striatum (Mayer et al, 2016) or regions of the tectofugal visual pathway (Mayer et al, 2013;Clark and Colombo, 2022).…”

“…Whether this type of information is processed by birds' hippocampus is not clear. Pattern discrimination is not expected to be hippocampus dependent in birds (Watanabe et al, 2008;Mayer et al, 2013;Clark and Colombo, 2022). However, visually responsive cells are actually present in pigeons' hippocampus, but it has not been investigated yet what kind of visual information they process (Scarf et al, 2016).…”