Understanding how the nervous system of animals recognizes salient stimuli in the environment, selects and executes appropriate behavioral responses is one of the fundamental questions in systems neuroscience. To facilitate the neuroethological study of visually guided behavior in larval fish, Bianko et al. (2011) developed virtual reality assays in which precisely controlled visual cues can be presented to larvae whilst their behavior is automatically monitored using machine vision algorithms. Freely swimming larval zebrafish, Danio rerio, responded to moving stimuli in an evident size-dependent manner. They turned towards small moving spots (1°) but reacted to larger spots (10°) with the high amplitude aversive turns. Bianco et al. (2011) adapted their virtual reality assay to deliver artificial visual cues to partially restrained larvae and found that small moving spots evoked convergent eye movements with J-turns of the tail. According to their assumption, eye convergence represents the predatory mode of behavior in larval fish and serves to increase the region of binocular visual space to enable stereoscopic targeting of prey.

Check basic references to understand other aspects of the neuromotor grounds of the behavioural responses to artificial and natural visual stimuli in the larval zebrafish.

Basic References

Bianco I.H., Kampff A.R., Engert F. 2011. Prey capture behavior evoked by simple visual stimuli in larval zebrafish. Frontiers in Systems Neuroscence 5, 1-13

Borla M.A., Palecek B., Budick S., O’Malley D.M. 2002. Prey capture by larval zebrafish: evidence for fine axial motor control. Brain, Behavior & Evolution 60, 207-229

Budick S.A., O’Malley D.M. 2000. Locomotor repertoire of the larval zebrafish: swimming, turning and prey capture. Journal of Experimental Biology 203, 2565-2579

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General

Studying behavioural responses of animals in experimental conditions, ethologists have found relatively simple stimuli that could be more effective than the natural objects. Single spots (called also eye-spots) and two horizontally arranged spots, rectangular longitudinal stripes, periodic gratings and other stimuli (Fig.1) belong to them. Because the foregoing stimuli are not exact imitations of the natural objects, we will call them amimetic stimuli. In several articles, we will group the main visual amimetic stimuli and describe how they are used in the ethological research, whether they occur in the nature as well as their application in the fishing lure industry.

In the framework of applied ethology, we will address to the fishing lure industry. It is that only sphere of the human activites, where artificial stimuli and models of the various animals are used in the largest scale.

Figure 1. The basic visual amimetic stimuli

Names of the basic visual amimetic stimuli used in this article:

Note, stimuli 05 and 06 are periodic spatial, whereas stimuli 07, 08, 09, 10, 11, and 12 are periodic spatiotemporal

In the terminology of early ethologists, some of the amimetic stimuli shown above called the sign stimuli (e.g., Manning & Dawkins, 1998). Generally, using simple stimuli and changing parts of complex stimuli, scientists were able to find the so called supernormal stimuli that induced in animals the more strong behavioural responses than the modelling natural objects.

For example, the giant cane toads, Bufo marinus, respond to the horizontally moving rectangular longitudinal stripes (20 mm long x 2.5 mm high) much more actively (on average of 10 times) than to live crickets and insect plastic models (Robins & Rogers, 2004). Similarly, reproductive males of the common toad, Bufo bufo, prefer (in four cases against one) to form sexual pairs (Fig.2) with the fixed blue discs (5 cm diameter) than with the live mobile females (Gnyubkin & Kondrashev, 1978).

Figure 2. Reproductive males of toads prefer to congregate sexual pairs with blue discs than with live females

Manning and Dawkins (1998) give many other examples of this kind.

Neuroethology

Visual amimetic stimuli induce numerous behavioural responses in many animals and do not imitate, as mentioned above, the concrete natural objects. The effectiveness of these stimuli is grounded on the common mechanisms of visual perception, common for all visually guided animals. Among visual amimetic stimuli, the nature of spots, stripes and gratings, both static and moving, as well as rotating striped drums is most studied.

For example, in fish and other vertebrate animals, spots are detected at the level of ganglion cells of retina, which have the more or less distinct concentric receptive fields with the antagonistic center and periphery. According to Horn (1962; see Fig. 6.5 b,c), ... Read more »