title: Responses to conflicting stimuli in a simple stimulus-response pathway.
abstract: The "local bend response" of the medicinal leech (Hirudo verbana) is a stimulus-response pathway that enables the animal to bend away from a pressure stimulus applied anywhere along its body. The neuronal circuitry that supports this behavior has been well described, and its responses to individual stimuli are understood in quantitative detail. We probed the local bend system with pairs of electrical stimuli to sensory neurons that could not logically be interpreted as a single touch to the body wall and used multiple suction electrodes to record simultaneously the responses in large numbers of motor neurons. In all cases, responses lasted much longer than the stimuli that triggered them, implying the presence of some form of positive feedback loop to sustain the response. When stimuli were delivered simultaneously, the resulting motor neuron output could be described as an evenly weighted linear combination of the responses to the constituent stimuli. However, when stimuli were delivered sequentially, the second stimulus had greater impact on the motor neuron output, implying that the positive feedback in the system is not strong enough to render it immune to further input.
authors: California Institute of Technology, Division of Biology, Pasadena, California 91125, and.
authors: Pieter Laurens
authors: PL
authors: Baljon
authors: California Institute of Technology, Division of Biology, Pasadena, California 91125, and University of Cincinnati, Department of Biological Sciences, Cincinnati, Ohio 45221 daniel.wagenaar@uc.edu.
authors: Daniel A
authors: http://orcid.org/0000-0002-6222-761X
authors: DA
authors: Wagenaar
mesh_terms: D000465:Algorithms; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D003220:Conflict, Psychological; D004558:Electric Stimulation; D055724:Electrophysiological Phenomena; D017952:Ganglia, Invertebrate / Q000502:physiology; D007865:Leeches / Q000502:physiology*; D009046:Motor Neurons / Q000502:physiology; D009434:Neural Pathways / Q000502:physiology*; D010812:Physical Stimulation; D012677:Sensation / Q000502:physiology*; D013239:Stereotyped Behavior / Q000502:physiology
keywords: invertebrate; neuronal circuits; sensory conflict; stimulus–response pathways