title: A neuronal network switch for approach/avoidance toggled by appetitive state.
abstract: Concrete examples of computation and implementation of cost/benefit decisions at the level of neuronal circuits are largely lacking. Such decisions are based on appetitive state, which is the integration of sensation, internal state, and memory. Value-based decisions are accessible in neuronal circuitry of simple systems. In one such system, the predatory sea slug Pleurobranchaea, appetite is readily quantified in behavior and related to approach/avoidance decision. Moreover, motor aspects of feeding and turning can be observed as fictive motor output in the isolated central nervous system (CNS). Here we found that the excitation state of the feeding motor network both manifested appetitive state and controlled expression of orienting versus avoidance. In isolated CNSs, spontaneous feeding network activity varied proportionally to donor feeding thresholds. CNSs from low- and high-feeding-threshold donors expressed fictive orienting or avoidance, respectively, in response to brief stimulation of sensory nerves. Artificially exciting the feeding network converted fictive avoidance to orienting. Thus, the feeding network embodied appetitive state and toggled approach/avoidance decision by configuring response symmetry of the premotor turn network. A resulting model suggests a basic cost/benefit decision module from which to consider evolutionary elaboration of the circuitry to serve more intricate valuation processes in complex animals.
authors.affiliation: Neuroscience Program, University of Illinois, 524 Burrill Hall, 407 South Goodwin Avenue, Urbana, IL 61801, USA. khiraya2@illinois.edu
authors.forename: Keiko
authors.initials: K
authors.lastname: Hirayama
authors.forename: Rhanor
authors.initials: R
authors.lastname: Gillette
mesh_terms: D000818:Animals; D001070:Appetitive Behavior / Q000502:physiology*; D002490:Central Nervous System / Q000502:physiology; D049851:Gastropoda / Q000502:physiology*; D006706:Homeostasis; D066298:In Vitro Techniques; D009415:Nerve Net / Q000502:physiology*