The geometry as an eyed fish feels it in spontaneous and rewarded spatial reorientation tasks

Abstract

Disoriented human beings and animals, the latter both sighted and blind, are able to use spatial geometric information (metric and sense properties) to guide their reorientation behaviour in a rectangular environment. Here we aimed to investigate reorientation spatial skills in three fish species (Danio rerio, Xenotoca eiseni, Carassius auratus) in an attempt to discover the possible involvement of extra-visual senses during geometric navigation. We observed the fish's behaviour under different experimental procedures (spontaneous social cued task and rewarded exit task), providing them different temporal opportunities to experience the environmental shape (no experience, short and prolonged experience). Results showed that by using spontaneous social cued memory tasks, fishes were not able to take advantage of extra-visual senses to encode the spatial geometry, neither allowing them short time-periods of environmental exploration. Contrariwise, by using a reference memory procedure, during the rewarded exit tasks, thus providing a prolonged extra-visual experience, fishes solved the geometric task, showing also differences in terms of learning times among species.

Learning by Doing: The Use of Distance, Corners and Length in Rewarded Geometric Tasks by Zebrafish (Danio rerio)

“…Differences in disoriented navigation under spontaneous or rewarded experimental conditions have been found also in fishes [22,23], in a similar way to mammals [33][34][35]. The behavioral protocols with fish species provide for two well-validated spatial problems: the "social cued memory task" [16][17][18]23] and the "rewarded exit task" [9,10,12,13,15,[20][21][22][23]. The social cued memory task consists in assessing spontaneous choices, where fish are required to approach the location of a social object (i.e., a companion) no-longer present, after a phase of passive disorientation.…”

“…Differences in disoriented navigation under spontaneous or rewarded experimental conditions have been found also in fishes [22,23], in a similar way to mammals [33][34][35]. The behavioral protocols with fish species provide for two well-validated spatial problems: the "social cued memory task" [16][17][18]23] and the "rewarded exit task" [9,10,12,13,15,[20][21][22][23].…”

“…Since there is high variability among underwater ecosystems and habitats, fish naturally face spatial orientation challenges, further showing noteworthy navigation capacities such as the use of compasses [3,4], landmarks [5,6], and cognitive maps [7,8]. Besides these skills, fish have been experimentally observed also in relation to the use of environmental geometric layouts to solve place-finding demands after induced disorientation [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. The term "environmental geometry" traditionally refers to macrostructural terrain-like characteristics of life-spaces where animals have to pinpoint worthwhile resources such as food, companions, and safe shelters, for survival.…”

“…The purpose of the present work was to investigate whether zebrafish could learn to use the geometric components characterizing a rectangular enclosure, in terms of distance, corners, and length, to gain a reward. Therefore, we adapted the experimental conditions by Lee and colleagues [17] within an apparatus previously used to test both spontaneous and rewarded extra-visual encodings of pure geometry in three-eyed fishes [23]. We performed four experiments, two of them in a rectangular transparent arena, whereas the other two in a square transparent arena.…”

Evolution and function of neurocognitive systems in non-human animals

“…In some of the studies included in this Collection, the same tasks are presented to different species, revealing interesting inter-specific differences in the behavioural response (e.g., in re-orientation spatial skills in different species of fish 13 ; in the use of geometric cues by rats and chicks 14 ). Relatedly, comparative research of this sort sometimes raises questions about the conditions in which different species are tested.…”