Meeting Abstract

P3.15  Wednesday, Jan. 6  Proximate explanations for differences in learning patterns and decision-making abilities of pitvipers (Viperidae: Crotalinae) KROCHMAL, Aaron R; LADUC, Travis J.; PLACE, Aaron J.*; Washington College; The Universtiy of Texas at Austin; Northwestern Oklahoma University ajplace@nwosu.edu

Decision making is at the center of all animal behaviors. However, the paucity of investigations into the mechanism of decision making, particularly among non-primates, combined with the lack of biological relevance of the majority of investigation into these mechanisms has left us with a poor understanding as to how decisions are made mechanistically. Recently, we described an experiment in which we investigated the ability of 13 species of pitviper – 7 rattlesnake and 6 non-rattlesnake pitvipers – to escape from a thermally stressful environment. Though all snakes were able to escape from the stressful environment equally well, rattlesnakes in the study learned to escape in one-trial (i.e., escape in subsequent trials was faster than trial 1), whereas non-rattlesnake pitvipers never decreased their escape time in 12 trials. Here we present a Bayesian statistical approach known as signal detection theory (SDT) to explain the behavior of pitvipers in thermally stressful situations. The main parameters of the model are a prior probability distribution (the probability a hypothesis is true before any evidence is obtained), evidence (neuronal firing rate in the somatosensory cortex), value (living or dying), a decision variable (derived from a likelihood ratio), and a decision rule (a constant based on the likelihood ratio). We present numerical estimates for these parameters that await experimental verification. The SDT model suggests profound differences in the neural processing abilities within the brains of rattlesnake and non-rattlesnake pitvipers. We suggest these changes in neural processing occurred at the divergence of rattlesnakes from the other pitvipers.