Tiger salamanders’ (Ambystoma tigrinum) response learning and usage of visual cues

Abstract

We explored tiger salamanders' (Ambystoma tigrinum) learning to execute a response within a maze as proximal visual cue conditions varied. In Experiment 1, salamanders learned to turn consistently in a T-maze for reinforcement before the maze was rotated. All learned the initial task and executed the trained turn during test, suggesting that they learned to demonstrate the reinforced response during training and continued to perform it during test. In a second experiment utilizing a similar procedure, two visual cues were placed consistently at the maze junction. Salamanders were reinforced for turning towards one cue. Cue placement was reversed during test. All learned the initial task, but executed the trained turn rather than turning towards the visual cue during test, evidencing response learning. In Experiment 3, we investigated whether a compound visual cue could control salamanders' behaviour when it was the only cue predictive of reinforcement in a cross-maze by varying start position and cue placement. All learned to turn in the direction indicated by the compound visual cue, indicating that visual cues can come to control their behaviour. Following training, testing revealed that salamanders attended to stimuli foreground over background features. Overall, these results suggest that salamanders learn to execute responses over learning to use visual cues but can use visual cues if required. Our success with this paradigm offers the potential in future studies to explore salamanders' cognition further, as well as to shed light on how features of the tiger salamanders' life history (e.g. hibernation and metamorphosis) impact cognition.

The effect of brumation on memory retention

“…The results of this study also lend support to the growing evidence of impressive spatial learning capabilities in amphibians2122. All twelve subjects successfully mastered the T-maze and appeared to do so using learned information rather than odour cues.…”

“…It remains unclear what specific information the animals used. They may have learned spatial information about the specific location of the reward (place learning), as was observed in the frog Allobates femoralis 21, alternatively, they could have learned a motor response (response learning) as was observed in the tiger salamander ( Ambystoma tigrinum )22. Irrelevant of the specific information retained, our findings show strong evidence of impressive long-term memory in the fire salamander.…”

“…Amphibians have traditionally been considered to have poor cognitive abilities (e.g. 19), however, recent research has revealed impressive behavioural flexibility in this group20 and there is now evidence of spatial learning in both frogs21 and salamanders22. Therefore, in this study fire salamanders were trained to make a spatial discrimination using a T maze.…”

A cognitive map in a poison frog

“…The bearing map encodes cues that provide directional information such as environmental gradients or distant beacons. Evidence for bearing maps in amphibians has been broadly found in field and laboratory experiments, including use of magnetic fields (Phillips, 1996;Shakhparonov and Ogurtsov, 2017), sensory beacons (Daneri et al, 2011(Daneri et al, , 2015Kundey et al, 2016;Liu and Burmeister, 2017;Liu et al, 2016;Ogurtsov et al, 2018;Sinsch, 1987Sinsch, , 1990Sinsch, , 2007Sinsch, , 2014 and arena geometry (Sotelo et al, 2015(Sotelo et al, , 2017. The sketch map, in contrast, stores topographical information by recording geometric relationships of position cues and corresponds to the classic definition of the cognitive map.…”

What the Salamander Eye Has Been Telling the Vision Scientist’s Brain

“…Despite the apparent simplicity of visually guided behavior in the salamander, recent investigations have shown surprisingly complex aspects. Tiger salamanders, for example, can learn to use visual cues to solve a Tmaze task (Kundey et al, 2016). And tongue-projecting salamanders can distinguish quantities of prey objects (Krusche et al, 2010) and extrapolate continuous motion to compensate for sensory processing delays (Borghuis and Leonardo, 2015).…”