Incentive or Habit Learning in Amphibians?

Abstract

Toads (Rhinella arenarum) received training with a novel incentive procedure involving access to solutions of different NaCl concentrations. In Experiment 1, instrumental behavior and weight variation data confirmed that such solutions yield incentive values ranging from appetitive (deionized water, DW, leading to weight gain), to neutral (300 mM slightly hypertonic solution, leading to no net weight gain or loss), and aversive (800 mM highly hypertonic solution leading to weight loss). In Experiment 2, a downshift from DW to a 300 mM solution or an upshift from a 300 mM solution to DW led to a gradual adjustment in instrumental behavior. In Experiment 3, extinction was similar after acquisition with access to only DW or with a random mixture of DW and 300 mM. In Experiment 4, a downshift from DW to 225, 212, or 200 mM solutions led again to gradual adjustments. These findings add to a growing body of comparative evidence suggesting that amphibians adjust to incentive shifts on the basis of habit formation and reorganization.

Retention and delayed extinction of an instrumental task in the toad Rhinella arenarum. Effect of the overtraining

“…Altogether, all these results indicate that amphibians, unlike mammals, follow a simple rule in which the strength of behavior during extinction is a direct function of reward magnitude during acquisition (Muzio et al, 1992(Muzio et al, , 2011). Amsel's (1992) frustration theory claims that paradoxical reward effects involve an emotional response of frustration due to the unexpected absence or devaluation of the reward.…”

“…After a few trials, the response recovers and both groups tend to respond similarly (e.g., Crespi, 1942;Elliott, 1928;Pellegrini &Mustaca, 2000;Pellegrini, Ruetti, Mustaca, &Muzio, 2004). Unlike in mammals, incentive devaluation in amphibians results in a gradual adjustment of their response to the level of the unshifted group, without going through a period of poorer performance (e.g., Muzio et al, 1992Muzio et al, , 2011. This effect is referred to as reversed successive negative contrast.…”

Use of local visual cues for spatial orientation in terrestrial toads (Rhinella arenarum): The role of distance to a goal.

“…The day before pretraining, standard weights (weight of the hydrated toad with its urinary bladder empty; Ruibal, 1962) of all toads were obtained. These weights varied between 50 and 102 g. To induce watersearch behavior, toads were dehydrated to 80% of their standard weights at the beginning of each pretraining and training session (a standard method employed in this species; e.g., see Muzio et al, 2011;Muzio, Segura, & Papini, 1992). This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.…”

Telencephalic Neuronal Activation Associated with Spatial Memory in the Terrestrial Toad <b><i>Rhinella arenarum:</i></b> Participation of the Medial Pallium during Navigation by Geometry

“…Experimental subjects began their training sessions dehydrated to 80% of their standard weight, a procedure widely used to motivate toads to search for water as a primary reinforcer [e.g. Muzio et al, 2011]. The inexperienced control subjects were also dehydrated.…”

“…Nonetheless, previous work on cognition in the terrestrial toad Rhinella arenarum demonstrated considerable learning abilities [e.g. Muzio et al, 1992Muzio et al, , 2011, particularly with regard to spatial learning and memory [Daneri et al, 2011[Daneri et al, , 2015. Though less complex compared to that of amniotes [e.g.…”